Dissertations / Theses on the topic 'Tectonic provenance'
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McArthur, Kelsey L. "Tectonic reconstruction and sediment provenance of a far-traveled nappe, west-central Norway." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1475187641&sid=15&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Sobczak, Katarzyna. "Investigating far-field tectonic events as drivers of provenance change in sedimentary basins." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/132493/1/Katarzyna_Sobczak_Thesis.pdf.
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This thesis greatly enhanced our understanding of the continental-scale links between sedimentary basins and far-field tectonic processes. A novel, multi-method approach was used to reveal a previously unknown, major mountain building event in southwest Queensland that fundamentally altered the history of the Drummond Basin in central Queensland. An unusually large river system was identified, which transported the gravel and sand across the basin from a distant source region. This thesis has provided new insights into the mid-Paleozoic geological history of the Australian continent, established new approaches to tracing the origin of sediment and resolving the complex histories of sedimentary basins.
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Pettersson, Carl Henrik. "The tectonic evolution of northwest Svalbard." Doctoral thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-39364.
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Svalbard represents the uplifted and exhumed northwest corner of the Barents Sea Shelf. Pre-Carboniferous rocks of Svalbard are divided into the Eastern, Northwestern and Southwestern Terranes, were amalgamated during the Caledonian Orogen and are separated by north-south-trending strike-slip faults. Even though our knowledge of Svalbard’s pre-Carboniferous history has increased dramatically during the last two decades, a major issue remains: Where did the different tectonostratigraphic terranes of Svalbard originate? The answer to this question has profound significance for the entire eastern Laurentian margin, which spans two supercontinent cycles, from the amalgamation and breakup of Rodinia to the amalgamation of Pangea. This thesis constrains the tectonothermal evolution of Svalbard’s Northwestern Terrane (NWT) using ion microprobe and LA-ICP-MS U-Pb zircon geochronology and electron microprobe thermobarometry on metasediments, clastic rocks and granitoids. Detrital zircon age populations of metasediments from the NWT suggests that they (e.g. the Krossfjorden Group) were deposited at c. 1000 Ma in a remnant ocean basin setting outboard the Eastern Grenville Province and were subsequently deformed and intruded by Late Grenvillian granitoids during the final suturing of Rodinia. Thus, a northern branch of the Grenvillian/Sveconorwegian orogeny is not present. This older history of the NWT is extensively overprinted by Late Caledonian deformation and metamorphism, with peak metamorphic conditions of 850 °C at >6 kbars, and subsequent migmatization of the Krossfjorden Group at c. 420 Ma. Based on these data, together with the detrital zircon age population from overlying Late Silurian-Early Devonian clastic rocks, a unifying model is proposed involving fragments from the Grampian orogen and Avalonian crust originally accreted to the Laurentian margin, subsequently transported northwards along sinistral strike-slip faults during Scandian deformation.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 4: In press.
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Zhang, Xiaojing. "Tectonic Evolution of Taimyr in the Late Paleozoic to Mesozoic from Provenance and Thermochronological Evidence." Doctoral thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-119046.
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The Taimyr Peninsula is a key element in the circum-Arctic region and represents thenorthern margin of the Siberian Craton. The Taimyr Peninsula is a late Paleozoic fold andthrust belt and preserves late Paleozoic through Mesozoic siliciclastic sedimentarysuccessions and providing an ideal location to investigate the Paleozoic to Mesozoictectonic evolution associated with the Uralian orogeny, the Siberian Trap magmatism andopening of Amerasia Basin within a circum-Arctic framework. Multiple methods areadopted, including petrography, heavy mineral analysis and detrital zircon U-Pbgeochronology for provenance investigation, apatite fission track dating for revealingthermal history and balanced cross section for understanding the deformation style ofTaimyr.The results of this thesis indicate that the Late Carboniferous to Permian sediments ofsouthern Taimyr were deposited in a pro-foreland basin of the Uralian orogen during theUralian orogeny. In the Triassic, the siliciclastic deposits still show a strong Uraliansignature but the initiation of Siberian Trap-related input begins to be significant. Erosionof the Uralian orogen has reached a deep metamorphic level. By Late Jurassic andCretaceous time, the deposition setting of southern Taimyr is an intracratonic basin.Erosion and input from Uralian sources waned while greater input from SiberianTrap-related rocks of the Taimyr region dominated. The Taimyr Peninsula underwent atleast three cooling and uplifting episodes: 280 Ma, 250 Ma and 220 Ma, corresponding tothe Uralian orogeny, the Siberian Traps and the late Triassic transpression.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: In press. Paper 3: Manuscript. Paper 4: Manuscript.
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Dayong, Vivian Anak. "Geochemistry and Mineralogy of Clastic Sediments of Tukau Formation: Implications on Provenance and Tectonic Setting." Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/75247.
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A study is proposed on the clastic sedimentary rocks of the Tukau Formation in the North-West Borneo using combined methods (i.e. geochemistry and petrography) to infer the provenance, tectonic setting and paleoweathering. Generally, Tukau sandstones are classified into quartz arenites , sublitharenites, litharenites, wacke and shale. Source rock is derived from the sedimentary to meta-sedimentary rocks dominated source with minor contribution from granitoids and ultramafic rocks. Tectonically, the Tukau Formation sedimentary rocks were deposited in a passive margin with minor extent towards active margin boundary.
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Peterson, John Aaron. "Geochemical Provenance of Clastic Sedimentary Rocks in the Western Cordillera: Utah, Colorado, Wyoming, and Oregon." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/439.
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Sedimentary rocks are an important source of information about previous orogenic conditions and the composition of which may describe the evolution of provenance and tectonic setting. Many factors influence sediment composition, namely, source rock composition, chemical weathering, climate, transport burial, and diagenesis. As the sediment composition changes through time, the geochemical characteristics of the sediment can be used to understand its geologic history.
The geochemical characteristics of clastic sedimentary rocks are useful in determining the depositional setting and its associated provenance. Although many different studies have used geochemical discriminants to evaluate provenance and tectonic settings, none have used a defined geochemical method. This study evaluates the present-day geochemical approaches to see which, if any, are the most useful.
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Asmussen, Pascal. "Insights from the Devonian Adavale Basin on the tectonic history of the Thomson Orogen." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/200906/1/Pascal_Asmussen_Thesis.pdf.
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This research aims to advance our understanding of the expansion of the Australian continent during the Palaeozoic. Geological remnants of specific sedimentary basins in southwest Queensland and north-western NSW were used as focus sites. A novel multi-method approach used sediment compositional information and Uranium-Lead mineral dating in combination with novel statistical methods to constrain the relative timing, sediment pathways and connectivity of these basins. The research showed that although a major period of stabilisation of the Australian continent had occurred by the beginning of the Devonian, approximately 400 million years ago, the new sedimentary basins were not yet directly connected.
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Becker, Thomas Patrick. "PALEOGEOGRAPHIC AND TECTONIC IMPLICATIONS OF THE LATE PALEOZOIC ALLEGHANIAN OROGEN DEVELOPED FROM ISOTOPIC SEDIMENTARY PROVENANCE PROXIES FROM THE APPALACHIAN FORELAND BASIN." UKnowledge, 2005. http://uknowledge.uky.edu/gradschool_diss/367.
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The Alleghanian orogeny was a collision between the Gondwanan and Laurentian continents that produced the Pangean supercontinent. Mechanical and kinematic models of collisional orogens are believed to follow a critical taper geometry, where the tectonic imbrication of continental crust begins nearest to the edge of continental plate and advances toward the craton in a break- forward sequence. Studies of shear zones within the Alleghanian collisional orogen, however, suggest that most of the early deformation was translational. Propagation of craton-directed thrusts into the foreland did not occur until the latest Pennsylvanian in the southern Appalachians, and the middle-late Permian in the central Appalachians. Radiometric sedimentary provenance proxies have been applied to the late Mississippian-early Permian strata within the Appalachian foreland basin to determine the crustal composition and structural evolution of the orogen during the continental collision. U-Pb ages of detrital zircons from the early to middle Pennsylvanian sandstones suggest that most of the detritus within the Appalachian basin was recycled from Mesoproterozoic basement and Paleozoic strata of the Laurentian margin. The presence of Archean and late Paleoproterozoic age detrital zircons is cited as evidence of recycling of the Laurentian syn-rift and passive-margin sandstones. Detrital zircon ages from early-middle Permian-age sandstones of the Dunkard Group do not contain any Archean or Paleoproterozoic detrital-zircon ages, implying a source of sediment with a much more restricted age population, possibly the igneous and metamorphic internides or middle Paleozoic sandstones from the Appalachian basin. The persistance of 360-400 Ma K/Ar ages of detrital white mica suggest that the sediment was supplied from a source that was exhumed during the Devonian Acadian orogeny. Detrital-zircon and detrital-white-mica ages from Pennsylvanian-age sandstones indicate that the late Paleozoic orogen did not incorporate any significant synorogenic juvenile crust. The 87Sr/86Sr ratios of middle Pennsylvanian-early Permian lacustrine limestones within the Appalachian basin show a slight enrichment through time, suggesting that labile 87Sr-rich minerals in the Alleghanian hinterland are being exposed. Stable isotopic data from the lacustrine limestones also corroborates that the Appalachian basin became much more arid through time.
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Roe, Warren Paul. "Tertiary Sediments of the Big Hole Valley and Pioneer Mountains, Southwestern Montana: Age, Provenance, and Tectonic Implications." The University of Montana, 2010. http://etd.lib.umt.edu/theses/available/etd-08232010-181233/.
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Tertiary terrestrial sedimentary rocks of the Big Hole basin and Pioneer Mountains of southwestern Montana provide a record of regional extensional tectonism. Detailed observations of stratigraphy and sedimentology at widely scattered outcrops indicate the presence of paleosols, fine-grained debris flows, small alluvial channels, and rare fluvial deposits. U-Pb geochronology of detrital zircons and air-fall tuffs indicates the presence of Oligocene to Middle Miocene sedimentary rocks outcropping at the surface. Though the presence of detrital muscovite in several outcrops indicates derivation from the nearby 2-mica Chief Joseph pluton, a predicted ~75 Ma zircon population is not present: instead, a persistent peak of 70-72 Ma zircons is found throughout the basin, indicating the Chief Joseph pluton may have a younger emplacement age than is currently recognized. Simple physical models developed from Bouguer anomalies indicate the basin deepens and widens toward the south, which agrees with prior work suggesting Eocene initiation of extension in the Big Hole and places it in a class of extensional basins that formed in the early Tertiary. Late Cretaceous, Eocene, and Mesoproterozoic detrital zircon populations, along with consistently immature lithic sands, all indicate sediments were derived from local bedrock sources found around the rim of the modern Big Hole Valley. While these results indicate the Tertiary Big Hole basin resembled the modern basin, some later deformation may have cut off and reversed a paleodrainage flowing out of the southeastern portion of the basin, possibly leading to the modern configuration of the Big Hole River and the deep gorge it carves across the eastern Pioneer Mountains.
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LaMaskin, Todd Allen. "Stratigraphy, provenance, and tectonic evolution of Mesozoic basins in the Blue Mountains Province, eastern Oregon and western Idaho /." Connect to title online (ProQuest), 2009. http://proquest.umi.com/pqdweb?did=1790314181&sid=2&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Nairn, Steven Peter. "Testing alternative models of continental collision in Central Turkey by a study of the sedimentology, provenance and tectonic setting of Late Cretaceous-Early Cenozoic syn-tectonic sedimentary basins." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5037.
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In central Anatolia, Turkey, a strand of the former northern Neotethys Ocean subducted northwards under the Eurasian (Pontide) active margin during Late Cretaceous–Early Cenozoic time. Subduction and regional plate convergence were associated with the generation and emplacement of accretionary complexes and supra-subduction zone-type ophiolites onto former passive margins of microcontinents. The resultant suture zones contain Late Cretaceous to Middle Eocene basins (“The Central Anatolian Basins”) including: 1) the Kırıkkale Basin; 2) the Çankırı Basin, 3) the Tuz Gölü Basin and; 4) the Haymana - Polatlı Basin. Using stratigraphic logging, igneous geochemistry, micropalaeontology and provenance studies, this study tests two end-member models of basin evolution. In model one, the basins developed on obducted ophiolitic nappes following closure of a single northern Neotethys Ocean during the latest Cretaceous. In model two, northern Neotethys comprised two oceanic strands, the İzmir-Ankara-Erzincan Ocean to the north and the Inner Tauride Ocean to the south, separated by the Niğde-Kırşehir microcontinent, which was rifted from the Gondwana continent to the south. In this scenario, the basins developed as accretionary-type basins, associated with north-dipping subduction which persisted until the Middle Eocene when continental collision occurred. Where exposed, the basements of the Central Anatolian Basins comprise the Ankara Mélange, a mainly Upper Cretaceous subduction-accretion complex and the western/northern margin of the Niğde-Kırşehir microcontinent. New geochemical data from the composite basement of the Kırıkkale Basin identify mid ocean-ridge basalt (MORB), here interpreted to represent relict Upper Cretaceous Neotethyan oceanic crust. During the latest Cretaceous, the Kırıkkale and Tuz Gölü Basins initiated in deep water above relict MORB crust and ophiolitic mélange, bordered by the Niğde-Kırşehir microcontinent to the east where marginal facies accumulated. Further west, the Haymana-Polatlı Basin represents an accretionary-type basin constructed on the Ankara Mélange. To the north, the Çankırı Basin developed on accretionary mélange, bounded by the Pontide active margin to the north. Palaeocene sedimentation was dominated by marginal coralgal reef facies and siliciclastic turbidites. Latest Palaeocene–middle Eocene facies include shelf-type Nummulitid limestone, shallow-marine deltaic pebbly sandstones and siliciclastic turbidites. This thesis proposes a new model in which two north-dipping subduction zones were active during the late Mesozoic within northern Neotethys. In the south, ophiolites formed above a subduction zone consuming the Inner Tauride Ocean until the southward retreating trench collided with the northern margin of the Tauride continent emplacing ophiolites and mélange. In the north, subduction initiated outboard of the Eurasian margin triggering the genesis of supra-subduction zone ophiolites; the subduction zone rolled back southwards until it collided with the Niğde-Kırşehir microcontinent, again emplacing ophiolites during latest Cretaceous time. Neotethyan MORB still remained to the west of the Niğde-Kırşehir microcontinent forming the basement of the Kırıkkale and Tuz Gölü Basins. Latest Palaeocene–middle Eocene regional convergence culminated in crustal thickening, folding, uplift and strike-slip faulting which represent final continental collision and the geotectonic assembly of central Anatolia.
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Becker, Thomas Patrick. "Paleogeographic and tectonic implications of the late paleozoic alleghanian orogen developed from radiometric sedimentary provenance proxies from the appalachian foreland basin." Lexington, Ky. : [University of Kentucky Libraries], 2005. http://lib.uky.edu/ETD/ukygeol2005d00240/tpb-dissertation.pdf.
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Thesis (Ph.D.)--University of Kentucky, 2005.Title from document title page (viewed on August 17, 2005). Document formatted into pages; contains: xi, 214 p. : col. ill. Includes abstract and vita. Includes bibliographical references (p. 181-211).
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Zobell, Elizabeth Anick. "Origin and Tectonic Evolution of Gondwana Sequence Units Accreted to the Banda Arc: A Structural Transect through Central East Timor." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/898.
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Petrographic and age analysis of sandstones, detailed structural analysis and gravity modeling were conducted to investigate the origin of the Gondwana Sequence in the Timor Region, and to better constrain the tectonic evolution of the active Banda Arc. Our field studies and U/Pb zircon age analysis helped assign most units to either Asian or Australian affinity. Detrital zircon from uplifted Banda forearc units (Asian affinity) have U/Pb ages as young as 80 Ma (Standley and Harris, in press). In contrast, analysis of detrital zircon from Gondwana Sequence sandstones accreted to the Banda Arc from Savu to East Timor are no younger than 234.6 ± 4.0 Ma, and have peak ages at 301 Ma and 1873 Ma with some Archean ages. These age constraints provide a reliable new application for distinguishing rocks units as Asian or Australian affinity. Petrographic and provenance analysis of Triassic Australian affinity greywacke units yield QFL abundances consistent with a proximal, syn-rift, intracratonic or recycled orogen source, from the northeast. The Mount Isa region to the east has the most similar peak U/Pb zircon ages to the Gondwana Sequence. However an extension of this terrane to the west, which would have rifted away during Jurassic breakup, is required to account for the immaturity of the sandstones. Structural measurements of Gondwana Sequence units accreted to the Banda Arc show a northwest - southeast paleo and current maximum stress direction, and vergence mostly to the southeast. Individual thrust sheets are 3 km thick and account for 50% total shortening. The deformational grain of Timor is a hybrid of the east-west strike of Banda Arc and northeast-southwest strike of incoming Australian continental margin structures. The Banda forearc, which is 200 km wide north of Savu, progressively narrows towards East Timor. In order to constrain the location of the forearc, three area-balanced structural models were tested against the gravity field of the Banda Arc. The best fit model requires internal shortening and under-stacking of the forearc beneath the arc, which may account for the cessation of volcanism and uplifted coral terraces north of East Timor.
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Ramarao, Thejashwini. "Provenance of the Carboniferous basin in Holm Land: implications for the Visean to Moscovian tectonic history of the North-East Greenland Caledonides." Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/5045.
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Carboniferous sedimentary units unconformably overlie eclogite-facies Paleoproterozoic basement gneisses in Holm Land, North-East Greenland and record change in provenance as a function of tectonic disturbances that happened during mid-Carboniferous time. The Visean Sortebakker Formation contains arkosic sandstone with abundant gneissic lithic grains and a heavy mineral suite dominated by titanite, apatite and rutile but lacking garnet. ICPMS U-Pb ages on detrital zircons define dominant age groups at 1.75 and 1.98 Ga, broad peaks at 1.1-1.5, 2.2-3.0 Ga, and a few Caledonian metamorphic ages between 350 and 400 Ma. In contrast, Moscovian arkosic sandstone of the unconformably overlying Kap Jungersen Formation contains a heavy mineral suite of titanite, apatite, rutile, garnet, and epidote and gives ICPMS U-Pb detrital zircon ages of 390 Ma, 1.75 Ga and 1.98 Ga. CL images demonstrate that low-U rims on some zircons record Caledonian metamorphism.
The dominant peaks in all samples are most compatible with derivation from the underlying gneissic basement of the North-East Greenland eclogite province. The 1.75 and 1.98 Ga peak ages match the protolith age of the Paleoproterozoic calc-alkaline arc related basement. The CL-bright, low-U metamorphic rims yield ages of 335 to 410 Ma that are consistent with metamorphic ages observed in the Paleoproterozoic basement rocks. The large number of discordant grains observed in the detrital populations (23-47%) in all samples is similar to age spectra from basement samples as well. Grains that define broad peaks at 1.1-1.5, 2.2-3.0 Ga in the Sortebakker samples are interpreted to be from metasedimentary units in the structurally higher Caledonian nappes (e.g., Independence Fjord Group). These grains make up 30-35% of the population in the basal units, diminishing to 10% up section. The Caledonian metamorphic grains, appearance of garnet and lack of the 1.1-1.5 and 2.2-3.0 Ga signatures indicate that the basal Kap Jungersen Formation lacked input from sources external to the underlying basement. Reappearance of the 1.1-1.5 and 2.2-3.0 Ga signatures higher in the section probably reflects recycling from the underlying Sortebakker section. Results of this study clearly demonstrate that dating of metamorphic rims of detrital zircons greatly enhances characterization of provenance and depositional history.
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Schneider, Sandra [Verfasser], Matthias [Akademischer Betreuer] Hinderer, and Christoph [Akademischer Betreuer] Schüth. "Paleogeographic and tectonic evolution of the western branch of the East African Rift System using multiple provenance methods (Albertine Rift, Uganda) / Sandra Schneider ; Matthias Hinderer, Christoph Schüth." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1194547745/34.
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Huber, Barbara [Verfasser], and Heinrich [Akademischer Betreuer] Bahlburg. "Provenance analysis of sediments from IODP Expedition 341 sites U1417 and U1418 : implications on climate-tectonic interactions at the southern Alaska continental margin / Barbara Huber ; Betreuer: Heinrich Bahlburg." Münster : Universitäts- und Landesbibliothek Münster, 2019. http://d-nb.info/1188706454/34.
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Teixeira, Alice Westin. "O Grupo Carrancas e a frente da Nappe Andrelândia na borda sul do Cráton do São Francisco: Proveniência sedimentar e implicações tectônicas." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/44/44143/tde-26092012-150855/.
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O Sistema de Nappes Carrancas compõe um sistema de nappes que circunda ao sul o Cráton do São Francisco e é formado pela Unidade Biotita Xisto e pelas formações Campestre e São Tomé das Letras do Grupo Carrancas. A Unidade Biotita Xisto contém veios de quartzo e xistosidade anastomosada e é formada por quartzo, biotita, muscovita, clorita e, localmente plagioclásio, carbonato e granada. A Formação Campestre é formada por quartzitos intercalados a filitos/xistos que variam de cloritóide filitos grafitosos, com muscovita, quartzo e turmalina e, localmente, granada a xistos com granada, estaurolita e cianita. A investigação da Unidade Biotita Xisto como autóctone em relação ao Cráton do São Francisco, seu potencial agrupamento com o Grupo Carrancas em uma megassequência deposicional, bem como sua comparação com a unidadealóctone Xisto Santo Antônio (Nappe Andrelândia) constituem parte dos objetivos deste estudo. Para tal, foram feitas análises químicas e isotópicas (Sr e Nd) em rocha total e geocronologia U-Pb em cristais de zircão detríticos, tanto na Unidade Biotita Xisto como na Formação Campestre, com intuito de elucidar a relação entre as mesmas e compará-las com dados da literatura disponíveis para o Xisto Santo Antônio. A Unidade Biotita Xisto apresenta características químicas compatíveis com sedimentos que sofreram intemperismo químico de intensidade e período de tempo moderados, depositados em ambientes de colisão continental, com área-fontecomposta essencialmente por rochas félsicas. Assinaturas de elementos traço e isotópicas de Sr ( \'ANTPOT.87 Sr\'/\'ANTPOT. 86 Sr\' entre 0,713 e 0,715) e Nd (\'\'épsilon\' IND.Nd\' entre -6 e -5) indicam contribuição de arco magmático e crosta continental e diferem, portanto, daquelas esperadas em ambientes de margempassiva. A mesma contribuição é observada para o Xisto Santo Antônio, cuja área fonte registra importante assinatura de material juvenil. As idades U-Pb LA-MC-ICP MS obtidas em cristais de zircão mostram contribuição principal de rochas do final do Criogeniano e contribuição secundária do Riaciano. A classe modal ao redor de 665 Ma é comparável com a idade cristais de zircão detrítico do Xisto Santo Antônio, o que aponta parauma mesma área-fonte principal para ambas unidades. A deposição dos sedimentos precursores da Unidade Biotita Xisto ocorreu entre 630-611 Ma, sendo as fontes principais os granulitos cálcio-alcalinos e rochas vulcânicas co-genéticas, além de granitos sin-colisionais da Nappe Socorro-Guaxupé. A pouca representatividade de idades paleoproterozóicas e a ausência de assinaturas químicas de margem passiva, inviabilizam as rochas do Cráton doSão Francisco como parte da área-fonte. Desta forma, a Unidade Biotita Xisto não é autóctone em relação ao Cráton do São Francisco, sendo, potencialmente, a unidade que compõe a frente da Nappe Andrelândia. Por outro lado, a Formação Campestre possui assinatura geoquímica de sedimentos que sofreram uma intensa reciclagem e alteração da composição do sedimento original. As assinaturas químicas de elementos traço e isotópicas Sr e Nd indicam contribuição de crosta continental superior, com componente de crosta antiga e sem afinidade com sedimentos depositados em margem passiva (\'ANTPOT.87 Sr\'/\'ANTPOT. 86 Sr\' entre 0,74 e 0,76; \'\'épsilon IND.Nd\' entre -18 e -15). Os zircões detríticos analisados forneceram idades U-Pb LA-MC-ICP-MS variadas, do Toniano ao Mesoarqueano, correlacionáveis com rochas vulcânicas e plutônicas do Cráton do São Francisco, com as faixas marginais do Cráton de Angola e/ou faixas orogênicas do Cráton Amazônico e com rochas dos arcos Mara Rosa e Goiás.A abrangência das idades U-Pb da Formação Campestre e das formações Chapada dos Pilões e Paracatu, permite a correlação, no Orógeno Brasília, entre os Grupos Carrancas e Canastra. A paleogeografia mais provável é a de um ambiente de rifte, antecessor à deriva e aoestabelecimento de uma margem continental passiva.The Carrancas Nappe System composes a system of nappes that surround the southern margin of the São Francisco Craton and is formed by the Biotite Schist Unit and by the Campestre and São Tomé das Letras formations of the CarrancasGroup. The Biotite Schist Unit encompass quartz veins and anastomosed schistosity and is formed by quartz, biotite, muscovite, chlorite and, locally plagioclase, carbonate and garnet. The Campestre Formation is composed by interleaved quartzites and phyllite/schist that varies from graphite-chloritoid phyllites, with muscovite, quartz, tourmaline and garnet, and locally garnet schists and schists with garnet, staurolite and kyanite. The investigation of the Biotite Schist Unit as authochtonous in relation to the São Francisco Craton, it´s potencial grouping with the Carrancas Group in a deposicional megassequence, as well as it´s comparison with the allochthonous Santo Antônio Schist (Andrelândia Nappe) is part of the goals of this study. For this purpose, chemical and isotopic (Sr and Nd) whole rock analysis were obtained, along with U-Pb detrital zircon data, in the Biotite Schist Unit and also in the Campestre Formation, in order to elucidate the relationship between these units and compare them with literature data available for theSanto Antônio Schist. The Biotite Schist Unit show chemical characteristics compatible with sediments that underwent chemical weathering of moderate intensityand time, deposited in continental collision setting, with source region composed essentially by felsic rocks. Trace elements and Sr isotopic signatures ( \'ANTPOT.87 Sr\'/\'ANTPOT. 86 Sr\' between 0,713 and 0,715) and Nd (\'\'épsilon IND.Nd\' between -6 and -5) points to contribution from magmatic arc and continental crust, and are different from the expected for passive margin settings. The same contribution is observed in the Santo Antônio Schist, which source area registers an important juvenile material signature. The U-Pb LA-MC-ICP MS zircon data show major contribution from rocks of the later Cryogenian and minor contribution from the Ryacian. The modal class around 655 Ma is comparable with the U-Pb detrital zircon data from the Santo Antônio Schist, pointing to the same source area for both units. The deposition of the precursors sediment of the Biotite Schist Unit occurred between 630 - 611 Ma, and the main sources were the calk-alcaline granulites and co-genetic volcanic rocks, besides the Socorro-Guaxupé Nappe sin-collisional granites. The low representation of Paleoproterozoic ages and the absence of passive margin chemical signatures preclude the rocks of the São Francisco Craton as part of the source area. Thus, Biotite Schist Unit is not an autochthonous unit in relation to the São Francisco Craton, and is, potentially, the unit that composes the Andrelândia Nappe front. On the other hand, the Campestre Formation has geochemical signatures of sediments that underwent intense recycling and alteration of the original sediment. The trace element and Sr and Nd isotopic signatures indicates upper continental crust contribution, with older crust component and no affinity with passive margin sediments ( \'ANTPOT.87 Sr\'/\'ANTPOT. 86 Sr\' between 0,74 and 0,76; \'épsilon\' IND.Nd\' between -18 and -15). The U-Pb LA-MC-ICP MS detrital zircon data provide varied ages, from the Tonian to the Mesoarchean, correlated withvolcanic and plutonic rocks of the São Francisco Craton, with the marginal belts of the Angola Craton, and/or orogenic belts of the Amazonian Craton and with the Mara Rosa and Goiás magmatic arcs. The range of the U-Pb ages of the Campestre Formation and the Chapada dosPilões and Paracatu formations, allows the correlation, in the Brasília Orogen, of the Campestre and Canastra groups. The most likely paleogeography is that of a rift setting, before the continental drift and the establishment of a passive continental margin.
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Zahid, Khandaker Uddin Ashraf. "Provenance and basin tectonics of Oligocene-Miocene sequences of the Bengal Basin, Bangladesh." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Fall/Thesis/ZAHID_KHANDAKER_14.pdf.
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Chakraborty, Suvankar. "PROVENANCE OF THE NEOPROTEROZOIC OCOEE SUPERGROUP, EASTERN GREAT SMOKY MOUNTAINS." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/76.
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The Ocoee Supergroup is a sequence of Neoproterozoic, immature, continental rift facies clastic sediments. Potential source rocks were tested by analyzing modes of detrital framework minerals, detrital mineral chemistry, whole rock geochemistry and detrital zircon U/Pb geochronology by LA-ICP-MS for Ocoee siltstone-sandstone dominated formations. Ocoee units are arkosic to subarkosic siltstones/sandstones, and ternary tectonic discrimination diagrams confirm a continental basement uplift source. Alkali feldspar predominates over plagioclase feldspar. Detrital feldspar compositions of Ocoee sediments as a group are similar to feldspar in local basement granitic rocks except for high-Ca plagioclase grains present locally in basement granitic rocks. The high alkali content of the detrital feldspars in the Ocoee Supergroup is consistent with derivation from an A-type granite source terrane. Normative Q-A-P values, calculated from wholerock chemistry, and trace element diagrams are also supportive of an A-type granite source for these rocks. The siltstones and sandstones of the Snowbird Group contain high abundances of heavy minerals (zircon, titanite, ilmenite, epidote and apatite), which are dispersed among other detrital grains and as concentrations of heavy minerals in discrete laminae. ZTR index and titanite mineral chemistry suggest a granitic source for these sediments. Detrital zircon geochronology in Ocoee sediments indicates a dominantly Grenville (1000 to 1300 Ma) source for these sediments. The youngest zircon age in the basal Ocoee Wading Branch Formation (639±8 Ma) is related to rift magmatism and provides a minimum depositional age for the Ocoee Supergroup.
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Zhang, Xiaojing. "Provenance of late Paleozoic and Mesozoic clastic sediments of Taimyr and their significance for understanding Arctic tectonics." Licentiate thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-89406.
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The Taimyr Peninsula is a key element in the circum-Arctic region and represents the northern margin of the Siberian Craton. The Taimyr Peninsula preserves late Paleozoic through Mesozoic clasitic sedimentary successions in its Mesozoic fold belt, providing an ideal location to investigate the Mesozoic tectonic evolution associated with the opening of Amerasia Basin within a circum-Arctic framework. This thesis aims to establish the tectonic setting in which the late Paleozoic through Mesozoic sediments of Taimyr were deposited, in order to correlate Taimyr with other Arctic terranes utilizing provenance investigations. Multiple methods are adopted, including petrography, heavy mineral analysis and detrital zircon U-Pb geochronology. The preliminary results of this work indicate that the late Paleozoic sediments of southern Taimyr were deposited in a foreland basin of the Uralian orogen during Uralian orogeny. The final collision between Baltica and Siberia in the last stage of Uralian orogenesis occurred between Early and Late Permian. Early Cretaceous sediments in northern Taimyr were mainly derived from Siberian Trap-related magmatism in Taimyr. Cretaceous sediment deposition is unrelated to Jurassic to Cretaceous rifting associated with the Verkhoyansk fold belt and instead relates to a rifting or post-rifting passive margin setting.
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Jones, Adam J. "Sediment Routing and Provenance of Shallow to Deep Marine Sandstones in the Late Paleozoic Oquirrh Basin, Utah." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563525409357944.
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Hull, Angela Lynn. "Geochronology and thermochronology of Precambrian basement drill core samples in Nebraska and southeastern South Dakota." Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1385078311.
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Hedeen, Tyler. "Provenance response to flat-slab subduction as recorded in detrital zircon signatures from the southern Alaskan forearc basin system." Thesis, University of Iowa, 2016. https://ir.uiowa.edu/etd/3094.
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Strata in the Cook Inlet forearc basin in south-central Alaska record the effects of tectonic events related to normal subduction and two flat-slab subduction events. Through detrital zircon geochronology we track provenance changes of strata deposited in a forearc basin in conjunction with these different subduction processes. Our data from strata deposited concurrent with normal subduction help to confirm previous provenance models of forearc basins that suggest provenance is sourced primarily from a proximal, coeval arc. However, compared to these models, our data from strata deposited coincident to flat-slab events show markedly different provenance signatures dependent upon: (1) geographic position relative to the flat-slab event; (2) pre-established, or lack thereof, topography; and (3) type of flat-slab event. Detrital zircon signatures of strata deposited in the Cook Inlet after flat-slab subduction of a mid-ocean ridge diversify to include older detritus found in the distal inboard region. This distal signature is then incrementally cut-off in younger strata due to deformation of the upper-plate from progressive insertion of a shallowly subducted oceanic plateau. Detrital zircon signatures for strata associated with each flat-slab event are largely older than depositional age due to the lack of coeval arc activity. Our data may help to improve the ability to recognize other flat-slab events through detrital zircon geochronology. In particular, changes in detrital zircon signatures found in strata deposited during flat-slab subduction of an oceanic plateau correlate well with the exhumation of rocks associated with the propagation of deformation in the over-riding plate due to plate coupling.
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Swain, Greg Martin. "Provenance and tectonics of the late Archaean mulgathing complex, central Gawler Craton : geochronological, geochemical and isotopic evidence for plume-arc interaction /." Title page, table of contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09SB/09sbs9715.pdf.
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Reid, Mattie Morgan. "Forearc basin detrital zircon provenance of Mesozoic terrane accretion and translation, Talkeetna Mountains-Matanuska Valley, south-central Alaska." Thesis, University of Iowa, 2017. https://ir.uiowa.edu/etd/5611.
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The Wrangellia composite terrane is one of the largest fragments of juvenile crust added to the North American continent since Mesozoic time, and refining its accretionary history has important implications for understanding how continents grow. New U-Pb geochronology and Hf isotopes of detrital zircons from Late Jurassic-Late Cretaceous strata from the forearc of the Wrangellia composite terrane allows more insight on the tectonic and paleogeographic history of the terrane.
Our stratigraphically oldest samples from the Late Jurassic Naknek Formation have a detrital zircon U-Pb signature dominated by Early and Late Jurassic grains (195-190 Ma; 153-147 Ma). Hf isotopic compositions of these grains are juvenile to intermediate (εHf(t)=4.5-14.7). Disconformably above the Naknek Formation are two poorly understood units Ks and Kc. The Ks unit is dominated by Early to Late Jurassic grains (159-154 Ma) with a few Paleozoic grains (347-340 Ma). Hf isotopic compositions of Carboniferous-Jurassic grains are juvenile to intermediate (εHf(t)=6.0-18.8). The overlying Kc unit has Late to Early Jurassic zircons (198-161 Ma), and an increase in Paleozoic ages (374-323 Ma). Hf isotopic compositions of these grains are juvenile to intermediate (εHf(t)=4.5-14.7). Samples from the Matanuska Formation have major Late Cretaceous grains (90-71 Ma), and minor Early Cretaceous (137-106 Ma), Late to Early Jurassic (200-153 Ma), Paleozoic (367-277 Ma), and Precambrian grains (2597-1037 Ma). Hf compositions have a wider range from both the Late Cretaceous grains (εHf(t)=-1.5-14.9) and Paleozoic-Precambrian grains (εHf(t)=-23.7-16.3).
Our results suggest an evolving provenance from Late Jurassic to Late Cretaceous time for the Wrangellia composite terrane forearc basin. The Late Jurassic Naknek Formation samples were dominantly derived from a juvenile to intermediate Jurassic igneous sediment source. During Early Cretaceous time, there is a slight increase in the number of Paleozoic grains in the Ks and Kc unit samples. The Early Cretaceous sediments have a mostly positive Hf isotopic compositions suggesting exhumation of Jurassic and Paleozoic juvenile igneous sediment sources. By Late Cretaceous time, our data illustrates another increase in Paleozoic grain abundances, in addition to the introduction of Precambrian grains, all with widely variable Hf isotopic compositions. We interpret this to reflect a larger sediment flux from the interior of Alaska where more evolved igneous rocks of that age are found.
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Soeprijo, Kertadikara Arti Widowati. "Variabilité génétique de quelques provenances de teck (tectona grandis l. F. ) et leur aptitude a la multiplication végétative." Nancy 1, 1992. http://www.theses.fr/1992NAN10368.
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Le teck (tectona grandis l. F. ) est un arbre dominant des forets tropicales semi-décidues de l'Asie du sud-est. La qualité de son bois justifie depuis longtemps sa plantation hors de son aire naturelle. Des mesures biométriques réalisées sur de jeunes plants élevés en serre et appartenant à 9 provenances (sept de l'Asie du sud-est et deux introduites en Afrique) montrent une meilleure croissance de la provenance de cote d'ivoire et une nette différenciation de deux provenances indiennes et d'une indonésienne par rapport aux autres. L'analyse sur 14 systèmes enzymatiques (18 locus polymorphes) des mêmes provenances met en évidence une variabilité entre provenances (fst=0,12): les populations indiennes forment un groupe homogène qui se distingue nettement de toutes les autres provenances étudiées (africaines, indonésiennes et thaïlandaises). Les populations montrent toutes un déficit en hétérozygotie (fis=0,18) malgré une forte allogamie (taux d'allofécondation multilocus de 10 descendances d'une provenance indienne: tm=0,98). Seul, la présence de certains allèles du locus gotb a présente des corrélations significatives avec plusieurs caractères biométriques. L'aptitude du teck à la multiplication vegetative (bouturage herbacé, micropropagation in vitro, culture d'apex et induction de bourgeonnement adventif à partir des cals) varie selon les provenances et les individus. La micropropagation a permis la multiplication et l'acclimatation en serre de 83 clones des 147 ortets utilisés. Les taux de multiplication, variables selon les clones, n'ont pas produit de changements dans la structure génétique de la population polyclonale obtenue par rapport à celle de l'ensemble des ortets utilisés. La croissance des clones a révélé une hétérogénéité des clones qui peut être due en partie au mode de multiplication. Des analyses biochimiques réalisées chez trois clones ont montre des écarts entre les valeurs observées chez les ortets et les ramets. Les profils enzymatiques des ramets ont présenté ainsi de nombreuses différences (18%) par rapport à ceux des ortets correspondants, ces différences s'atténuent avec le temps
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Robertson, Peter Benjamin. "Part I| Neoacadian to Alleghanian foreland basin development and provenance in the central appalachian orogen, pine mountain thrust sheet Part II| Structural configuration of a modified Mesozoic to Cenozoic forearc basin system, south-central Alaska." Thesis, Purdue University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1565119.
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Foreland and forearc basins are large sediment repositories that form in response to tectonic loading and lithospheric flexure during orogenesis along convergent plate boundaries. In addition to their numerous valuable natural resources, these systems preserve important geologic information regarding the timing and intensity of deformation, uplift and erosion history, and subsidence history along collisional margins, and, in ancient systems, may provide more macroscopic information regarding climate, plate motion, and eustatic sea level fluctuations. This thesis presents two studies focused in the Paleozoic Appalachian foreland basin system along the eastern United States and in the Mesozoic to Cenozoic Matanuska forearc basin system in south-central Alaska.
Strata of the Appalachian foreland basin system preserve the dynamic history of orogenesis and sediment dispersal along the east Laurentian margin, recording multiple episodes of deformation and basin development during Paleozoic time. A well-exposed, >600 m thick measured stratigraphic section of the Pine Mountain thrust sheet at Pound Gap, Kentucky affords one of the most complete exposures of Upper Devonian through Middle Pennsylvanian strata in the basin. These strata provide a window into which the foreland basin's development during two major collisional events known as the Acadian-Neoacadian and the Alleghanian orogenies can be observed. Lithofacies analysis of four major sedimentary successions observed in hanging wall strata record the upward transition from (1) a submarine deltaic fan complex developed on a distal to proximal prodelta in Late Devonian to Middle Mississippian time, to (2) a Middle to Late Mississippian carbonate bank system developed on a slowly subsiding, distal foreland ramp, which was drowned by (3) Late Mississippian renewed clastic influx to a tidally influenced, coastal deltaic complex to fluvial delta plain system unconformably overlain by (4) a fluvial braided river complex. Four samples of Lower Mississippian to Middle Pennsylvanian sandstone were collected from the hanging wall (n = 3) and footwall (n = 1) of the Pine Mountain thrust sheet at Pound Gap to determine sediment provenance in this long-lived foreland basin system. Paleocurrent indicators considered in the context of the regional foreland basin system suggest transverse regional drainage during the development of Early and Late Mississippian delta complexes. Eustatic fall during the early stages of the Alleghanian orogeny to the east saw a shift in regional drainage with the development of a southwestward-flowing and axial braided river system in Early Pennsylvanian time followed by Middle Mississippian transgression of a fluvio-deltaic complex. Detrital zircon U-Pb age data from Lower Mississippian to Lower Pennsylvanian sandstone support regional interpretations of sediment sourcing from probably recycled foreland basin strata along the east Laurentian margin, whereas compositionally immature Middle Pennsylvanian sediment was sourced by a limited distribution of east Laurentia sources reflecting thrust belt migration into the adjacent foreland basin system during Alleghanian orogenesis.
In addition, the stratigraphy of the foreland basin system in the central Appalachian basin is significantly different compared to the stratigraphic record that is typified for foreland basin systems and suggests that the Carboniferous Appalachian foreland basin system investigated in this study does not fit the typical foreland basin model that is used widely today for both ancient and modern systems. Possible factors that produce the observed discrepancies between the central Appalachian and typical foreland basin systems may include differences in the timing, type, and frequency of orogenic events leading to foreland basin development, related variations in the rheology of the underlying lithosphere, and whether forebulge migration is mechanically static or mobile.
The Cordilleran margin of south-central Alaska is an area of active convergence where the Pacific plate is being subducted at a low angle beneath the North American plate. In the Matanuska Valley of south-central Alaska, the geology of the Mesozoic to Cenozoic Matanuska forearc basin system records a complex collisional history along the margin from Cretaceous to Miocene time and provides an opportunity to study how shallow-angle subduction affects upper plate processes. Paleocene-Eocene low-angle subduction of an eastward migrating spreading ridge and Oligocene oceanic plateau subduction caused uplift, deformation, and slab window magmatic intrusion and volcanism in the Matanuska Valley region, thereby modifying the depositional environment and structure of the forearc system. In this study, detailed field mapping in the Matanuska Valley region and structural analysis of Paleocene-Eocene nonmarine sedimentary strata are utilized to better understand the structural response of the forearc basin system to multi-stage flat-slab subduction beneath an accreted continental margin, a process observed along multiple modern convergent margins. Four geologic maps and structural cross-sections from key areas along the peripheries of the Matanuska Valley area and one regional cross-section across the forearc system are presented to delineate its local structural configuration and to contribute to a more complete understanding of how sedimentary and tectonic processes along modern convergent margins may be or have been impacted by shallow-angle type and related subduction processes.
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Ibrahim, Diar Mohammed. "High-resolution sequence stratigraphy and detrital zircon provenance of the Ordovician Ancell Group in the Iowa and Illinois Basins: insight into the evolution of midcontinental intracratonic basins of North America." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/3108.
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The Middle Ordovician Ancell Group, including the St. Peter Sandstone, Glenwood Shale and Starved Rock Formation, records intracontinental basin development during eustatic sea level changes in Iowa and Illinois. The St. Peter Sandstone overlies the Prairie du Chien Group across an erosional unconformity that marks a major sequence boundary, whereas upper contact of the St. Peter Sandstone with the Glenwood Shale also is a second sequence boundary. Data from 80 wells, selected well logs, and 20 cores were integrated to refine the high-resolution sequence stratigraphy of the Ancell Group. Two main sequences bounded by three sequence boundaries are interpreted to represent 3rd order sequences. Distinctive shallowing-upward parasequences bounded by flooding surfaces in many cores record higher frequency relative sea level fluctuations in the Ancell Group, but these cannot presently be correlated regionally. Facies variations define an aggradational transgressive systems tract TST), a prograding highstand systems tract (HST) and down stepping falling stage system tract (FSST) in both the St. Peter Sandstone and the Glenwood Shale-Starved Rock Formation units. The St. Peter Sandstone thickens towards the northeast and thins to the northwest and southwest in Iowa. In contrast, the St. Peter Sandstone in Illinois thickens to the south likely recording a prolonged FSST incised valley or channel fill. Detrital zircon geochronology of 13 samples from the St. Peter Sandstone and Starved Rock Formation define common peaks at 1100-1500 Ma and 2500-2700 Ma with minor components at 1670-1750 Ma and 3000-3600 Ma. The detrital zircon signature is dominated by Archean, and Grenville (1000-1300 Ma) ages. The detrital zircon geochronology indicates that the Ancell Group was sourced directly from the Archean Superior Province to the north and Grenville Province to the northeast, although recycling of Archean grains from the Paleoproterozoic Huron Basin cannot be ruled out. The near complete lack of 1800-1900 Ma ages argues against derivation of detritus from the Trans-Hudson or Penokean Orogens. The Transcontinental Arch northwest of the Iowa Basin acted as a barrier to sediment transport from the Trans-Hudson Orogen. Basement rocks of the Penokean Orogen are inferred to have been covered by water or younger sediments southeast of the Iowa Basin. CIA analyses of Ordovician shale samples from around the Transcontinental Arch indicate that the climate condition during Middle Ordovician time was warm and humid. This is consistent with a paleoclimate interpretation where mechanical erosion and chemical weathering yielded first cycle mature quartz arenites (Witzke, 1980).
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Lowe, David. "Sedimentology, Stratigraphic Evolution and Provenance of the Cambrian – Lower Ordovician Potsdam Group in the Ottawa Embayment and Quebec Basin." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35303.
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The Cambrian – Lower Ordovician Potsdam Group is a mostly siliciclastic unit that provides important insight into the paleoenvironmental, geologic and tectonic history of Early Paleozoic Laurentia. Nevertheless, in spite of 178 years of study the Potsdam in the Ottawa Embayment and Quebec Basin remains poorly understood. Also poorly understood is how the Potsdam relates with coeval strata regionally.
In this work six siliciclastic paleoenvironments are recognized: (a) braided fluvial, (b) ephemeral fluvial, (c) aeolian, (d) coastal sabkha, (e) tide-dominated marine and (f) open-coast tidal flat. Fluvial strata were examined in particular detail and interpreted to consist of two end-member kinds. Braided fluvial deposits are dominated by low-relief bars formed in wide, shallow channels; however where basement structures limited the lateral growth of channels, flows were deeper and bar deposits thicker and higher angle. In contrast, ephemeral fluvial strata are dominated by sheetflood splay sedimentation with rare preservation of scour-filling supercritical bedform strata – all later subjected to aeolian reworking. In the upper Potsdam, alternating ephemeral and braided fluvial strata provide a record of climate change, which, respectively, correlate with documented global cool (arid) and warm (humid) periods during the Late Cambrian and Early Ordovician.
Three allounits are recognized in Potsdam strata, recording regional episodes of sedimentation and facilitating correlation with coeval strata throughout eastern North America. These correlations, aided with provenance data from detrital zircons, show that changes in the areal distribution of sediment supply, accommodation and deposition/erosion were principally controlled by episodic reactivation of the Neoproterozoic Ottawa graben, which then periodically modified the stratigraphic expression of the ongoing Sauk transgression. Specifically, episodes of tectonic reactivation occurred during late Early to Middle Cambrian (allounit 1), late Middle to early Late Cambrian (allounits 2 – 3 unconformity), and Earliest Ordovician (allounits 3 – 4 unconformity). The earliest episode is correlated to regional extension of southern Laurentia, whereas the latter two are linked to peri-Laurentian accretion events that triggered reactivation of the Ottawa graben via the Missisquoi oceanic fracture zone.
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Ely, Kim Susan. "Geochronology of Timor-Leste and seismo-tectonics of the southern Banda Arc." Connect to thesis, 2009. http://repository.unimelb.edu.au/10187/7063.
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Arc–continent collision is a significant plate boundary process that results in crustal growth. Since the early stages of evolution are often obscured in mature orogens, more complete understanding of the processes involved in arc–continent collision require study of young, active collision settings. The Banda Arc presents an exceptional opportunity to study a young arc–continent collision zone. This thesis presents aspects of the geology and geochronology of Ataúro and the Aileu Complex of Timor-Leste, and the tectonics of the Banda Arc.U–Pb dating of detrital zircons from the Aileu Complex by LA-ICPMS show major age modes at 270–440 Ma, 860–1240 Ma and 1460–1870 Ma. The youngest zircon populations indicate a maximum depositional age of 270 Ma. The detrital zircon age populations and evidence for juvenile sediments within the sequence favours a synorogenic setting of deposition of sediments sourced from an East Malaya – Indochina terrane.
Previous uncertainty in aspects of the cooling history for the Aileu Complex is resolved with 39Ar/40Ar geochronology of hornblende. Cooling ages of 6–10 Ma are established, with the highest metamorphic grade parts of the Complex yielding the older ages. Cooling ages of 10 Ma imply that metamorphism of the Aileu Complex must have commenced by at least ~12 Ma. Metamorphism at this time is attributed to an arc setting rather than the direct result of collision of the Australian continent with the Banda Arc, an interpretation consistent with the new provenance data.
Geological mapping of Ataúro, an island in the volcanic Banda Arc north of Timor, reveals a volcanic history of bi-modal subaqueous volcanism. 39Ar/40Ar geochronology of hornblende from dacitic lavas confirms that volcanism ceased by ~3 Ma. Following the cessation of volcanism, coral reef marine terraces have been uplifted to elevations of 700 m above sea level. Continuity of the terraces at constant elevations around the island reflects regional-scale uplift most likely linked to sublithospheric processes such as slab detachment.
North of Timor, the near complete absence of intermediate depth seismicity beneath the inactive segment of the arc is attributed to a slab window that has opened in the collision zone and extends to 350 km below the surface. Differences in seismic moment release around this slab window indicate asymmetric rupture, propagating to the east at a much faster rate than to the west. If the lower boundary of this seismic gap signifies the original slab rupture then the slab window represents ~4 m.y. of subsequent subduction and implies that collision preceded the end of volcanism by at least 1 m.y.
Variations in seismic moment release and stress state across the transition from subduction of oceanic crust to arc–continent collision in the Banda Arc are investigated using earthquake catalogues. It is shown that the slab under the western Savu Sea is unusual in that intermediate depth (70–300 km) events indicate that the slab is largely in down-dip compression at this depth range, beneath a region of the arc that has the closest spacing of volcanoes in the Sunda–Banda arc system. This unusual state of stress is attributed to subduction of a northern extension of the Scott Plateau. Present day deformation in the Savu Sea region may be analogous with the earliest stages of collision north of Timor.
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Van, Noord Kenrick A. A. "Deep-marine sedimentation and volcanism in the Silverwood Group, New England Fold Belt, Australia." Thesis, Queensland University of Technology, 1999.
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In eastern Australia, the New England Fold Belt (NEFB) comprises an ancient convergent margin that was active from the Paleozoic until the late Mesozoic. Considerable effort has been expended in understanding the development of this margin over the past twenty years. However, proposed tectonic models for the orogen have either been too broad, ignoring contradictory local evidence, or too locally specific without paying attention to the 'big picture'. The research presented in this work addresses the issue of appropriate scale and depth of geological detail by studying the NEFB at the terrane-scale. Using one succession, the Silverwood Group of southeast Queensland, this work demonstrates that detailed sedimentological studies and basin analysis at the terrane-scale can help to refine hypotheses regarding the tectonic evolution of the NEFB.
The Silverwood Group (Keinjan terrane), located approximately 140 km southwest of Brisbane, Australia, is a succession of arc-related basins that developed within an ancient intraoceanic island-arc during the mid-Cambrian to Late Devonian. From the base of the succession, the group consists of five formations totalling -9700 m. These include the Risdon Stud Formation (2500 m), Connolly Volcanics (2400 m), Bald Hill Formation (2450 m), Ormoral Volcanics (600 m) and the Bromley Hills Formation (1700 m). The Long Mountain Breccia Member (300m) is a separate unit which forms the lower part of the Bromley Hills Formation. The entire succession has been thrust west over the Late Devonian to Early Carboniferous Texas beds. Elsewhere, the Silverwood Group is unconformably overlain by and faulted against Early to Late Permian units including the Rokeby beds, Wallaby beds, Tunnel beds, Fitz Creek beds, Eight Mile Creek beds, Rhyolite Range beds and Condamine beds. Of these Permian units, all but the Condamine beds form part of the Wildash Succession. To the west, southwest and south, the Silverwood Group is intruded by the Late Triassic Herries and Stanthorpe Adamellites. All of these sequences and the two plutonic intrusives are unconformably overlain by the Jurassic sediments of the Marburg Sandstone.
The Silverwood Group and Texas beds consist of various lithologies including grey, purple- grey, green and green-grey volcaniclastic conglomerates, sandstones, siltstones or mudstones, massive and laminated chert, polymict or monomict breccias, muddy breccias, muddy sandstones, and volcanic rocks. Volcanic rocks include various tholeiitic metabasites, dolerite, meta-andesites and infrequent metadacite. In the Silverwood Group, these volcanic rocks are often accompanied by mafic pyroclastic rocks (e.g. peperite and hyaloclastite). Facies analyses of these lithologies has led to the recognition of 19 deep-marine turbiditic and volcanic/volcaniclastic facies that were deposited by three main processes: i) gravity-flow processes (e.g. low- and high-density volcaniclastic turbidites and mass-flows), ii) chemical/biological processes (siliceous oozes- chert) and iii) direct initiation by volcanic processes (e.g. flows, hypabyssal intrusions and associated pyroclastic facies).
For the Silverwood Group, the defined facies occur in distinct vertical associations that form recognisable 3rd and 4th-order architectural elements such as channel, levee, suprafan lobe, outer-fan, basin plain, mass transport complex, volcanic flows, syn-sedimentary sills and syn-sedimentary emergent cryptodomes. These architectural elements are represented in a series of deep-marine depositional environments including slope, shelf-edge failure, submarine-fan and subaqueous basaltic volcanoes. The Risdon Stud Formation and parts of the Connolly Volcanics were deposited along a 'normal' clastic or mud, mud/sand-rich and/or sand/mud-rich slope. Both upper and lower slope environments are represented and in both formations, the slope is speculated to have faced eastwards and prograded away from an active arc located west. Sediments from both successions accumulated at palaeodepths of 1200 to 2000 m.
Although sediments from the upper part of the Bald Hill Formation were also deposited on a slope, these sequences have subsequently collapsed into the depocentre to form extensive slump deposits accompanied by olistoliths of older arc crust. The lower part of the Bald Hill Formation formed by similar processes, although the failure was far more extensive (>20 km along strike). This latter part of the formation is interpreted to be a major shelf-edge failure succession. Upper parts of the Bald Hill Formation also accumulated at palaeodepths of 1200 to 2000 m, but the deposition of these sediments occurred farthest from the shelf and at the greatest depth compared to the Risdon Stud Formation and Connolly Volcanics. Lower parts of the Bald Hill Formation were deposited at palaeodepths of approximately 1700 m.
Subaqueous basaltic volcanoes are prominent in the Connolly Volcanics, Bald Hill Formation and Ormoral Volcanics. In the Bald Hill Formation, igneous rocks were emplaced into the shelf-edge failure succession as a series of syn-sedimentary sills and cryptodomes. These high-level hypabyssal rocks occasionally became emergent above the sediment-water interface, whereupon they were partially resedimented. In some parts of the Bald Hill Formation, the hypabyssal intrusions were blanketed by basin plain deposits that are contemporaneous with the slumps and olistoliths in the upper part of the formation. The intrusive rocks were emplaced at 1700 m palaeodepth.
Unlike the Bald Hill Formation, the Ormoral Volcanics and lower parts of the Connolly Volcanics form thick accumulations of extrusive volcanic and pyroclastic rocks that built a significant volcanic pile. Volcanic and pyroclastic facies within these successions were deposited proximal to their source (0-10 km of vent). Extrusive rocks within the Ormoral Volcanics are thought to be derived from intrabasinal fissure-vents located at palaeodepths of 1700 to 3100 m. Igneous rocks from the Connolly Volcanics, Bald Hill Formation and Ormoral Volcanics have the petrological and geochemical characteristics of back-arc basin basalts (BAB) that were sourced from undepleted to slightly enriched Fertile MORB Mantle-wedge (FMM). The FMM material was variably enriched in trace elements by fluids derived from the subducting slab prior to emplacement of the igneous rocks. Immediately following emplacement, these rocks were hydrothermally metamorphosed under conditions of low-pressure and transitional low to high-temperature (200-300 °C). By contrast, igneous rocks within the Texas beds lack enrichment in subduction components and are characteristic of N-MORB.
The Bromley Hills Formation is a sand-rich point-source submarine fan deposited at palaeodepths of 500 to 2000 m. The fan was initiated by a mass transport complex resulting from subaerial collapse of a basaltic-andesitic stratovolcano. The submarine fan is characterised by two repetitive stages of retrogressive sedimentation during which channel-levee elements (inner-fan channels) are overlain by suprafan lobe elements (mid-fan) and then by outer-fan deposits as sea-level rises within the depocentre. Both inner-fan channels and suprafan lobes show centralised stacking patterns with limited lateral migration that indicate the depocentre was laterally restricted during sedimentation (e.g. submarine ridges). The Bromley Hills Formation exhibits all the characteristics typical of an active margin fan that formed by a combination of tectonic stage initiation followed by eustatically controlled regressive deposition.
Volcaniclastic sediments of the Silverwood Group range in composition from lithic to lithic- feldspathic wackes and arenites, although they are mainly lithic or feldspathic-lithic wackes and arenites. Many samples are tuffaceous (25-75% pyroclasts), particularly those from the Connolly Volcanics, Ormoral Volcanics and Bromley Hills Formation. Samples in the Bald Hills Formation and Texas beds can be classified as quartz-rich. The majority of the Silverwood Group was sourced from an undissected intraoceanic island-arc, although sediments within the Bald Hill Formation exhibit a provenance that is characteristic of uplift within the arc (recorded as a 'strike-slip continental arc' model). Epiclastic sediments from the Texas beds were sourced from a transitional to dissected continental arc.
Formations of the Silverwood Group were mostly deposited in a series of intra-arc basins within an ancient intra-oceanic island arc, although the lowermost formation developed in a marginal basin (Risdon Stud Formation). All of the basins were located east of the active arc (behind the arc), keeping in mind the present location of the Group relative to the Texas-Coffs Harbour megafold. The entire succession formed during four-phases of arc-related basin development that coincide with major changes in the strain regime of the arc. From the base of the succession, these changes are: I) mid Cambrian to late Silurian marginal basin sedimentation- relative compression within the arc (Risdon Stud Formation), II) late Silurian to Early Devonian intra-arc rifting- relative extension within the arc (Connolly Volcanics), Ill) Early to early Middle Devonian basin collapse followed by intra-arc rifting- relative extension to compression (Bald Hill Formation and Ormoral Volcanics) and IV) early Middle to Late Devonian intra-arc submarine fan sedimentation- relative compression (Bromley Hills Formation).
Comparing the Silverwood Group against equivalent terranes of Cambrian to Devonian age within the New England Fold Belt (NEFB) suggests that the Gamilaroi terrane, Calliope Volcanic Assemblage, Willowie Creek beds and Silverwood Group all formed as one intraoceanic island-arc during the Early to Late Devonian. Prior to this, significant differences in the sedimentological evolution of these terranes suggests that they occupied different positions relative to each other within the one arc. It is proposed that the NEFB formed as a result of dual west-directed subduction zones during the Cambrian to Middle Devonian period. During this time, a single intraoceanic island-arc located seaward of the Australian craton developed above a west-directed subduction zone. This arc was separated from the craton by a marginal sea. A second west-directed subduction zone was located beneath a continental arc developed on the Australian craton. Cambrian to Early Devonian terranes within and along the Peel Fault are proposed to form a part of the ancient subduction zone present beneath the intraoceanic island-arc (Weraerai and Djungati terranes). Collision of the intraoceanic island-arc occurred during the Late Devonian, at which point west-directed subduction occurred beneath the Australian craton and the accreted intraoceanic island-arc. Following collision, a new continental volcanic arc was established that was active during the Late Devonian to Early Carboniferous.
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Roberts, Richard James. "The Seiland Igneous Province, Northern Norway : age, provenance, and tectonic significance." Thesis, 2008. http://hdl.handle.net/10539/4993.
Full textAbstract:
The Seiland Igneous Province, of which 5400 km2 is exposed, is hosted within a
discrete terrane within the northernmost part of the Caledonian orogenic belt. The
Province consists of numerous mafic and ultramafic plutons emplaced into a
sedimentary succession indicative of a continental setting. Accompanying this mafic
magmatism is a significant volume of intermediate monzonitic and dioritic rock
(10% of the total exposed igneous rock), as well as numerous nepheline syenite and
carbonatitic intrusions.
This study reports ID-TIMS U-Pb analyses on magmatic zircons from a range of
intrusions, which indicate that the bulk of the Seiland magmatism took place between
560 Ma and 570 Ma, whereas previous studies had produced a range of ages between
420 Ma and 830 Ma. The data indicate that only one magmatic episode is represented
in the rocks of the Seiland Igneous Province, invalidating previous models involving
multiple rifting events over a period of 300 m.y.
Detailed geochemical investigation of several plutons from an evolved high alkali
suite of gabbroic intrusions in the Seiland Igneous Province has shown that these
plutons are generally enriched in trace elements compared to layered intrusions from
other areas across the globe, but that geochemically the gabbros are relatively
homogenous. The rocks yield εHf and εNd values for the gabbroic rocks ranging from
+8 to -6 and from +4 to -4, respectively, indicative of the contamination of mantlederived
material with crustal material. The most primitive isotopic values are similar
to those obtained from the carbonatites and nepheline syenites, indicating the same
mantle source gave rise to the magmas that were subsequently emplaced as the
Seiland Igneous Province. The homogeneous trace element content of the different
mafic rocks most likely indicates a relatively homogeneous mantle source for the
original magmas of the province, which has subsequently been affected by processes
of assimilation and crustal contamination. The monzonitic and dioritic bodies in the
Seiland Igneous Province are not derived from melted silicic crustal material and
may have been formed by the melting of pre-existing mafic material.
The new geochronology invalidates the metamorphic framework previously
proposed for the Seiland Igneous Province, which postulated several orogenic events
between the emplacement of the magmas and the Caledonian Orogeny. There is no
evidence for metamorphic activity in the period between 570 Ma and 420 Ma, and
there are monazites in gneissic rocks hosted within mafic rocks of Seiland age that
preserve an age of 640 Ma. This leads to the conclusion that only one metamorphic
event, the 420 Ma Caledonian Orogeny caused by the collision of Baltica and
Laurentia, affected the Seiland terrane after the emplacement of the Seiland magmas.
The new data obtained lead to a model for the evolution of the Seiland Province in
which a number of heavily modified and contaminated mantle-derived mafic
magmas derived from the mantle were emplaced into the continental crust of the
Seiland nappe between 560 and 570 Ma. This magmatism was accompanied by the
injection of alkaline magmas into the same area of the crust, and the melting of mafic
rock emplaced earlier. This magmatic event is considered to have occurred in an
extensional stress regime, possibly during intracontinental rifting or back-arc
spreading. This event took place well before the 420 Ma Caledonian Orogeny, and
thus the Seiland Igneous Province can be considered a remnant of an older geological
terrane that was emplaced onto the margin of Baltica during the Caledonian
Orogeny.
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Lloyd, Jarred Cain. "Geochronology, Provenance, and Tectonic Evolution of the Adelaide Superbasin, South Australia." Thesis, 2022. https://hdl.handle.net/2440/136061.
Full textAbstract:
The Neoproterozoic (1000–538 Ma) was a period of some of the most significant changes to Earth’s systems throughout its c. 4.5-billion-year history. The tectonic system drove the final amalgamation of Rodinia, subsequent breakup coinciding with the emplacement of numerous large igneous provinces, and the initial stages of Gondwana amalgamation during the late Ediacaran. Current evidence suggests two long lived global glacial events occurred, the Sturtian and Marinoan glaciations, with both thought to be Snowball Earth events. These significant changes driven by Earth’s systems appear to have culminated in a nutrient rich ocean, a progressive rise in atmospheric oxygen concentration, the proliferation of eukaryotic and metazoan life, and the evolution of the earliest confirmed animalia, the Ediacaran fauna.
The Neoproterozoic–Cambrian rocks of the redefined Adelaide Superbasin (formerly Adelaide Geosyncline) hold one of the most complete records of this pivotal time in Earth’s history. These records include key sequences of the Cryogenian global glaciations, the Ediacaran Acraman bolide ejecta layer, the eponymous Ediacaran fauna, and the global boundary stratotype section and point (GSSP) for the base of the Ediacaran.
Despite the important record the Adelaide Superbasin holds, our knowledge of the chronology and tectonic evolution of it is still a hindrance to the calibration of other investigative techniques like chemostratigraphy, and for the development of global correlation frameworks for these Earth system events and stratigraphic sequences. While a significant corpus of research has been done to address these same issues around the globe, particularly in Canada, China, Ethiopia, Namibia, Scotland, and Svalbard, geochronology of Neoproterozoic sequences remains a significant challenge due to the fragmented, eroded, and commonly deformed stratigraphic record of the Neoproterozoic. The primary purpose of this research is to address the knowledge gap in the detrital zircon record of the Adelaide Superbasin to refine the chronostratigraphic framework, and to revise the tectonic and palaeogeographic model for the Adelaide Superbasin within the Neoproterozoic.
This thesis presents over 6,500 new detrital zircon data from a significantly greater spatial and temporal diversity of samples from the Neoproterozoic of the Adelaide Superbasin—this is approximately half of the now available detrital zircon data for the basin. The research presented here suggests that deposition in the Adelaide Superbasin began between c. 890 Ma and 830 Ma, in half-graben depocentres resultant from far-field extensional forces. The rift system propagated along existing crustal weaknesses in an overall southerly direction, with major extensional pulses c. 830 Ma, c. 790 Ma (north), and c. 750–730 Ma (south) reflected by abrupt changes in zircon provenance. The northern region of the Adelaide Superbasin became an aulacogen with the opening of the proto-Pacific likely developing in the southern regions of the basin, heading northeast around the Curnamona Province. Detrital zircon spectra show a return to predominantly local sediment derivation during deposition of the Yudnamutana Subgroup, representative of the Sturtian glaciation. This is attributed to both glacial scouring of the surrounding region and disruption in sediment supply from distal sources due to the widespread nature of the glaciation. Beyond this time, derivation from distal sources became increasingly prevalent as the basin continued to develop through sag phases, with overall sedimentation becoming gradually shallower through the Neoproterozoic as the basin filled. This research has also led to a suggestion that an unrecognised Stenian–Tonian zircon source lay to the north/northeast of the basin. Finally, the rocks characterised by thick glaciogenic diamictite in the Yudnamutana Subgroup are all redefined as the Sturt Formation, resolving years of conjecture.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 2022
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Shaw, Jessica. "Oroclines of the Iberian Variscan belt: Tectonic and paleogeographic implications." Thesis, 2015. http://hdl.handle.net/1828/6508.
Full textAbstract:
The Western European Variscan orogenic belt is thought to represent the final in a series of Paleozoic continental collisions that culminated with the amalgamation of the supercontinent Pangea. The Iberian segment of the Variscan belt is characterized by Cantabrian orocline, which is 180º and convex toward the west. Several lines of evidence are at odds with classical interpretation of the Cantabrian orocline as the core of the much larger ‘Ibero-Armorican’ arc, suggesting instead that it is structurally continuous with a second more southerly and complimentary orocline. Paleocurrent data collected from the Lower Ordovician Armorican Quartzite of the deformed Iberian Paleozoic passive margin sequence confirm the existence of the so-called Central Iberian orocline. Structural continuity between the Cantabrian and Central Iberian oroclines suggests that they formed contemporaneously and in the same fashion. Mesoscale vertical-axis folds deforming slaty cleavage and shear fabric within the Ediacaran Narcea Slates have a dominant vergence toward the hinge of the Cantabrian orocline, suggesting that its formation was in part accommodated by a mechanism of flexural shear during buckling of a linear belt in response to an orogen parallel principle compressive stress. The Cantabrian-Central Iberian coupled oroclines therefore palinspastically restore to an originally linear belt 2300 km in length. Provenance analysis of detrital zircons sampled from the Armorican Quartzite along a 1500-km-long segment of the palinplastically restored Iberian passive margin indicate that it originated in a paleogeographic position stretching east-west along the northern limits of north African Gondwana, from the Arabian-Nubian Shield to the Saharan hinterland. Paleomagnetic data and the distribution of Variscan ophiolites support a model of mid-Paleozoic separation of the Variscan autochthon (Armorican continental ribbon) from north Gondwana preceding or in conjunction with a 90º rotation required to reorient the ribbon to a Late Carboniferous north-south trend. Formation of the Iberian coupled oroclines accommodated 1100 km of orogen parallel shortening. The Western European Variscan belt, North American Cordillera, and Eastern European Alpine system are orogens similarly characterized by both coupled oroclines and paleomagnetic inclinations that are significantly shallower than cratonic reference values. Palinspastic restoration of the Alaskan and Carpathian–Balkan coupled oroclines fully resolves inclination anomalies within the Cordillera and Eastern Alpine system, respectively. Inclination anomalies within the Iberian Variscan belt are only partially resolved through palinspastic restoration of the Iberian coupled oroclines, but the sinuous geometry of the belt is not yet fully deciphered. Oroclines within the Western European Variscan belt, not the orogen itself, provide the true record of Pangean amalgamation.Graduate
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Higgie, D. R. "Tectonic provenance of the Palaeoproterozoic Plum Tree Volcanics: implications for the initiation of the McArthur Basin." Thesis, 2018. http://hdl.handle.net/2440/130627.
Full textAbstract:
This item is only available electronically.The Palaeoproterozoic (1825 ±4Ma) Plum Tree Volcanics are a bimodal suite of basalt and rhyolite lavas forming part of the fluvial conglomerate-sandstone sequence of the upper Edith River Group. They are preserved in remnants unconformably overlying the Pine Creek Orogen north of Katherine in the Edith River, Mt Callanan and Birdie Creek Basins. These sequences directly post-date the convergent deformation of the Pine Creek Orogen and mark the beginning of the extensional regime that initiated the McArthur Basin. The tectonic setting of the Plum Tree volcanism, whether divergent intraplate rift or mantle hotspot, may suggest how the formation of the McArthur Basin began and provide insight into how the Pine Creek Orogen compression ceased. In this paper, geochemical methods were used to determine the tectonic setting of the Plum Tree Volcanics. Whole rock geochemical data were collected via XRF, ICP-MS and ICP-OES. Nd-Sm and Sr isotopic data were collected via column chromatography and TIMS. Petrographic data were collected via optical petrography. Radiogenic Sr (87Sr/86Sr= ~0.708) and non-radiogenic Nd (εNd(i)= -6 to -8) isotopes suggest a crustal component in melt evolution. Modelling of melt evolution by pure fractional crystallisation presents well-fitting liquid lines of descent, suggesting a fractional crystallisation driven melt evolution. Tholeiitic basalts and trace element geochemistry suggests a mantle derived melt driven by a mantle plume and intraplate continental rifting. Modelling of AFC processes suggest a lower crust sourced assimilant. Ambiguous basalt geochemistry supports a continental rift derived melt and an oxygen fugacity of FMQ -1 suggests a primitive, reduced melt reflecting a mantle parent. Optical petrography presents a plagioclase and clinopyroxene rich mineral assemblage reflecting a mantle parent.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2018
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Plavsa, Diana. "The tectonic evolution of the Southern Granulite Terrane of India and its role in the amalgamation of Gondwana." Thesis, 2014. http://hdl.handle.net/2440/84918.
Full textAbstract:
The southernmost portion of the Indian subcontinent, the Southern Granulite Terrane of India, holds a pivotal role in the reconstructions of the Ediacaran-Cambrian supercontinent Gondwana. Bound to the west by Madagascar and the East African continental fragments and to the east by Sri Lanka and Antarctica, this terrane offers a breadth of information regarding across terrane correlations and palaeotectonic settings, Arguably, within the Southern Granulite Tenane, the most debated issue of all is the existence of a late Neoproterozoic (ca. 550 - 500 Ma) suture zone between the Salem and Madurai Blocks, termed the Palghat Cauvery ShearZone (or alternatively, the Cauvery Shear Zone). The U-Pb zircon geochronology of the orthopyroxene-bearing orthogneisses (charnockites) in the northern part of Madurai Block yielded Neoarchaean and Cryogenian (ca.2.7 - 2.5 Ga and 795 ± 17 Ma) crystallization ages with metamorphic overprinting at ca. 535 Ma. Their Nd and Sr isotopic ratios (εNd₍τ₎ = -16.9 and +4.55, ⁸⁷Sr/⁸⁶Sr = 0.7017 - 0.7567) suggest they were generated by variable mixing of mantle-derived magmas with the older Archaean crust. The charnockites and garnet-biotite bearing granitoids in the southern part of the Madurai Block yielded much younger crystallization (1007 ± 23 Ma and 784 ± 18Ma) and Nd depleted mantle model ages ranging between 1.69 Ga and 1.38 Ga with low initial ⁸⁷Sr/⁸⁶Sr ratios of 0.7054 - 0.7084, suggesting that the Madurai Block is not a uniform crustal domain, The age of metamorphism in this southern part of the Madurai Block is similar to that further north and indicates isotopic disturbance and zircon growth during the Ediacaran-Cambrian metamorphism. The coupled U-Pb and Lu-Hf isotopic study of the metasedimentary rock packages from the Salem Block mainly yielded late Archaean to early Palaeoproterozoic (ca. 2.7 - 2.45 Ga) detrital zircon ages with εHf values between +0.3 and +8.8, suggesting derivation from largely juvenile sources. ln contrast, the metasedimentary rocks from the Madurai Block are dominated by Mesoarchean to Palaeoproterozoic detrital zircon ages (ca. 3.2 Ga and 1.7 Ga) to the north and Mesoproterozoic to Neoproterozoic (ca. 1.5 - 0.65 Ga) detrital zircon ages in the south. Collectively, the Hf isotopic signatures of detrital zircons from the Madurai Block suggest they were derived from variably mixed reworked Archaean and Palaeoproterozoic sources, with additional input from the juvenile Palaeoproterozoic, late Mesoproterozoic and evolved Neoproterozoic sources. When compared to the metasedimentary rock packages from adjacent tenanes in Gondwana, the Madurai Block metasedimentary rock units correlate best with the basement sources derived from East Africa. The disparity between the delrital signatures from the Salem and Madurai Block suggest they had dissimilar depositional histories until the latest Neoproterozoic, The Palghat Cauvery Shear System (PCSS) at the southernmost margin of the Salem Block, represents a network of anastomosing crustal-scale shear zones with a largely dextral offset. The careful structural field observations coupled with U-Pb zircon geochronology of cross-cutting pegmatites, leucosomes and deformed basement gneisses show that the deformation in the Palghat Cauvery Shear System (southern Salem Block) is not a result of a single deformational event. Rather, the E-W and NE-SW trending fabrics that characterize much of the northern portion of the PCSS formed during an early Palaeoproierozoic (ca. 2.5 - 2.48 Ga) metamorphic event associated with largely dextral strike-slip motion. This deformation is overprinted by the E-W and ESE-WSW trending fabrics in the southern part of the PCSS (the Cauvery Shear zone) associated largely with dip-slip and minor dextral strike-slip contractional deformation suggesting dextral transpression. This latest deformation is loosely constrained to ca. 740 - 550 Ma. The Madurai Block deformational events (D₁– D₄) are different in character to those further north and are constrained to ca. 550 - 500 Ma. The latest Neoproterozoic event (ca. 550 - 500 Ma) appears to have affected both the southern portion of the Salem Block and all of the Madurai Block and is most likely linked to the final stages of Gondwana amalgamation. This study also suggest that care should be taken when regarding the regional-scale structural fabrics of the PCSS as being associated with the latest Neoproterozoic metamorphism. The Southern Granulite Terrane records two major episodes of magmatism at ca. 2.7 - 2.43 Ga and 0.83 - 0.75 Ga. ln the Salem Block, the ca. 2.7 – 2.5 Ga magmatism is associated with production of tonalitic-trondhjemitic-granitic (TTG) magmas during partial melting of basaltic/amphibolitic sources with limited contributions directly from the mantle, similar to the "typical" Archaean TTG provinces worldwide. Somewhat younger (ca. 2.54 - 2.43 Ga) basement rocks in the Madurai Block also show some similarities to the Archean TTG rocks further north. However, a large portion of the gneisses also show higher K₂O/Na₂O ratios, Ni and Cr concentrations and Mg numbers (molar ratio of MgO/(MgO + FeO)) suggesting higher inputs from the mantle during their genesis. The Cryogenian aged magmatism (ca. 0.8 - 0.75 Ga) in the Salem Block is associated with production of highly alkaline magmas (syenites/carbonitites/ultramafics), while in the Madurai Block similarly aged magmas are calc-alkaline, largely granitic to granodioritic, with high LILE/HFSE and LREE/HFSE ratios, low Ni and Cr concentrations typical of magmas generated above a subduction-zone. The differences in the structural character, age and geochemistry of the basement gneissic rocks as well as the differences in the depositional histories of the metasedimentary rock units between the Salem and Madurai Blocks suggests these two domains underwent widely different tectonothermal histories prior to the latest Neoproterozoic orogeny associated with the amalgamation of Gondwana. This study strongly supports a presence of a terrane boundary (a suture zone) between the Salem and Madurai Blocks.Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2014
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Martínek, Karel. "Climatic, tectonic and provenance record of the Upper Palaeozoic non-marine deposits of the Krkonoše Piedmont Basin." Doctoral thesis, 2009. http://www.nusl.cz/ntk/nusl-274389.
Full textAbstract:
Přírodovědecká fakulta University Karlovy v Praze Ústav geologie a paleontologie Charles University in Prague, Faculty of Science Institute of Geology and Palaeontology Klimatický, tektonický a provenienční záznam svrchnopaleozoických kontinentálních sedimentů podkrkonošské pánve Climatic, tectonic and provenance record of the Upper Palaeozoic non-marine deposits of the Krkonoše Piedmont Basin. Mgr. Karel Martínek Autoreferát doktorské disertační práce Summary of the PhD Thesis školitel (supervisor): Doc. RNDr. Stanislav Opluštil, Ph.D. školitel - konzultant (consultant): Prof. RNDr. Jiří Pešek, DrSc. Praha, 2008 Prague, Czech Republic, 2008 Úvod Podkrkonošská pánev je vnitrohorskou pozdně (až post-) variskou strukturou, která pokrývá plochu až 1100 km2 (to zahrnuje i partie překryté mořskými sedimenty svrchnokřídového stáří). Pánev se vytvořila jako součást systému extenzních/transtenzních pánví, ve kterých započala subsidence v pozdních fázích variské orogeneze. Pánev se nachází na severovýchodě českého masívu mezi krkonošsko-jizerským krystalinikem na severu, orlicko-sněžnickým krystalinikem na jihovýchodě a sedimenty české křídové pánve na jihu a jihozápadě (viz obr. 1). Maximální vrty ověřená mocnost vulkanosedimnetární výplně dosahuje v centru pánve téměř 1800 m, ve východní části pánve, na...
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Noguera, L. Mariela I. "Analysis of provenance of Late Cretaceous - Eocene turbidite sequences in northern Venezuela tectonic implications on the evolution of the Caribbean /." 2009. http://purl.galileo.usg.edu/uga%5Fetd/noguera%5Fmariela%5Fi%5F200908%5Fms.
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Schneider, Sandra. "Paleogeographic and tectonic evolution of the western branch of the East African Rift System using multiple provenance methods (Albertine Rift, Uganda)." Phd thesis, 2019. https://tuprints.ulb.tu-darmstadt.de/8787/1/Paleogeographic%20and%20tectonic%20evolution%20of%20the%20western%20branch%20of%20the%20East%20African%20Rift%20System%20using%20multiple%20provenance%20methods%20%28Albertine%20Rift%2C%20Uganda%29.pdf.
Full textAbstract:
As part of the DFG-funded interdisciplinary research project 703 RiftLink – Rift Dynamics, Uplift and Climate Changes in Equatorial Africa (H1643-7/1), this presented PhD thesis aims at reconstructing the evolutionary history of the Albertine Rift in the western branch of the East African Rift System by combined studies on ancient rift sediments and modern stream sediments. The major part of this thesis is dedicated to the Miocene-Pleistocene rift infill that has been studied for its provenance and depositional history in order to gain a broader understanding of rift dynamics and the tectono-sedimentary history of the Albertine Rift since its initiation in the early Miocene. Sedimentary successions of rift sediment studied in the Albertine Rift are exposed in two key areas on the Ugandan side of Lake Albert, the Kisegi-Nyabusosi area and Nkondo-Kaiso area. Both areas represent a distal and proximal setting with respect to the extremely upthrusted > 5000 m high Rwenzori Mountains, which form a promontory of the eastern rift flank of the Albertine Rift. The rift sediment mainly comprises unconsolidated siliciclastics from clay to coarse gravel deposited in a fluvial-deltaic to lacustrine setting during multiphase rifting. Based on systematic logging and sampling of sedimentary outcrops, this study presents a multi-proxy methodological approach that combines framework and heavy mineral petrography, bulk sediment geochemistry, varietal studies of detrital garnet and rutile, as well as U-Pb zircon geochronology. The outcome of this thesis is a paleotectonic model of erosion, sediment transport, and basin evolution that presents a more detailed picture of the spatial-temporal history of the northern western branch of the East African Rift System. The second part of this doctoral thesis focuses on modern river sediment collected in the Rwenzori Mountains and adjacent rift flanks. This additional study complements this thesis by providing profound insights into present-day sediment generation and erosional processes in this particular rift setting. By using the same analytical approach as for the rift fill, the modern stream sediment helps to identify the characteristics of a variety of Ugandan basement rocks and to define potential source rocks for the Neogene successions. Furthermore, this study aims at quantifying the effects of chemical weathering on the composition of modern sediment generated under extreme equatorial climatic conditions. The synthesis of available information collected during this provenance study allows to modify and refine existing evolutionary models for the Albertine Rift. Three major rifting stages were identified that may be interpreted in terms of rifting activity:
Early Miocene to early Pliocene (~17.0 –5.0 Ma)
Exposures of the earliest rift sediment are only known from the southern Lake Albert sub-basin (Kisegi-Nyabusosi area). Provenance data imply that sediment transport was dominated by a westward directed large-scale river system and flowed from Kenya westwards through Uganda and probably further towards the Congo Basin and to the Atlantic Ocean. Sediment sources extend towards the at least 400 km away located East African Orogen as demonstrated by the occurrence of Pan-African zircon ages. The dominant source represents gneissic-granulitic rocks of the Neoarchean North Uganda Terrane that occupies major parts of the Ugandan basement proved by a high amount of Neoarchean zircon as well as amphibolite- to granulite-facies garnet and rutile.
Early Pliocene to late Pliocene (~5.0–2.6 Ma)
A major provenance shift occurred during the Miocene-Pliocene boundary, interpreted to mark the transition from the pre-rift into the syn-rift stage with enhanced subsidence and uplift of rift flanks and the Ugandan plateau. Sediment transport from distal sources was largely disrupted, likely due to a phase of first major rifting affecting the Albertine Rift. This can mainly be concluded from a change in the heavy mineral composition and missing of Neoproterozoic zircon ages. Provenance data indicate proximal sediment sources for both the southern and northern study areas, probably from the adjacent rift margin with major derivation from the North Uganda Terrane as indicated by a majority of Neoarchean zircon, epidote-amphibolite-dominated heavy mineral assemblages, as well as high-grade metamorphic garnet and rutile (amphibolite- to granulite-facies).
Early Pleistocene (since ~2.6 Ma)
A further provenance shift around the Pliocene-Pleistocene transition is concurrent with the beginning of the extreme uplift of the Rwenzori fault block and the initiation of inversion tectonics in the Albertine Rift. In the southern Albertine Rift, sediment supply from mainly southern sources with major supply from the Rwenzori Fold Belt in the Rwenzori Mountains is indicated by less mature sediment accompanied by the occurrence of lower-grade metamorphic garnet and rutile (amphibolite-facies), as well as pinkish zircon grains. On the contrary, additional input from the Neoproterozoic Bunyoro Group overlying the local basement along the rift shoulder leads to a higher maturity of the sediment in the further to the north located Nkondo-Kaiso region with higher abundances of more resistant minerals, like quartz, zircon and tourmaline. In both areas, sediment sources changed only slightly compared to the Pliocene and sediment transport is still from the adjacent rift flank.
The proposed provenance changes are coincident in both study areas and largely coincide in timing with major faulting episodes in other parts of the EARS, suggesting that tectonic movements in eastern Africa act at a global scale. Present-day sediment generation in the Albertine Rift takes mainly place under hot-humid climate conditions and in contrasting geomorphological settings, including poorly-drained lowlands of the rift plateau and the high-altitude Rwenzori horst, in which two fundamental types of sediment is created. In the extremely uplifted and young Rwenzori horst, where high topography promotes rapid physical degradation, sediment is rich in feldspar and rock fragments with very rich heavy-mineral assemblages controlled by amphibole and epidote. Sediment created in the low-relief rift plateau, widely covered by thick lateritic soils, is highly quartzose due to intense weathering prolonged over millions of years. The study of modern sediment in the Albertine Rift clearly demonstrates that identification of original provenance signatures is still possible even in areas characterized by extreme climatic conditions such as those of equatorial latitudes. Heavy Mineral spectra, zircon geochronology, garnet and Rutile chemistry, and geochemical parameters, especially non-mobile elements and element ratios, best preserve the imprint of the source-rock lithology. Altogether, this study Highlights the high potential of sedimentary provenance Analysis (SPA) in reconstructing the sedimento-tectonic history of rift basins in tropical regions, and also underlines the importance of multi-proxy approaches to fully understand sediment supply into depositional systems. The research on the Albertine Rift exemplifies that the application of SPA is most successful byusing a combination of ‘traditional’ petrographic-mineralogical methods with ‘innovative’ geochemical and geochronological methods. Single-grain varietal studies on zircon, garnet and rutile are the most powerful applications to constrain specific sources. While age populations obtained from zircon U-Pb geochronology can be directly linked to the Age of a certain tectono-thermal terrane, chemical compositions of garnet of rutile allow distinguishing lithologies characterized by different metamorphic overprint, e.g., amphibolite-facies vs. granulite-facies rocks. However, varietal studies fail for recovering sediment input from recycled sedimentary rocks. Because of the durability of zircon, garnet and rutile during the sedimentary cycle, polycycle sedimentation is masked, which might lead to an incorrect interpretation of exclusively primary sources. For reconstructing provenance from sedimentary (recycled) lithologies or for revealing the weathering degree of sediments, bulk-rock petrographic and geochemical methods proofed to be the most suitable application.
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Zhou, Jianping. "Cretaceous to Cenozoic thermo-tectonic evolution and provenance analysis of the basement and some sedimentary successions northeast of the Songliao Basin, NE China." Doctoral thesis, 2021. http://hdl.handle.net/21.11130/00-1735-0000-0005-1584-E.
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亀高, 正男, and Masao Kametaka. "Provenance of the Upper Triassic Mine and Nariwa Groups in Southwest Japan : implications for the paleogeography and tectonic evolution of the Triassic in East Asia." Thesis, 2000. http://hdl.handle.net/2237/16345.
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Drobe, Malte. "Neoproterozoische bis paläozoische Krustendynamik am Westrand des Río de la Plata Kratons." Doctoral thesis, 2009. http://hdl.handle.net/11858/00-1735-0000-0006-B2E9-E.
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Hartmann, Ari. "Newly discovered Mesozoic rift basins in the Virginia Blue Ridge : sedimentology, provenance, structure, and tectonics /." 2008. http://hdl.handle.net/10288/573.
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Tsai, Chia-Hsin, and 蔡佳欣. "Tectonic development and sediment provenances of the Luzon Island and Hengchun Peninsula from detrital zircon analysis." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/5zp28r.
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碩士國立臺灣大學
地質科學研究所
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The Philippines and Taiwan are both in the western Philippine Sea Plate that has complicated tectonics. Located in the northern Philippine Archipelago that is an amalgamation of tectonic terranes, the Luzon Island is in the middle of two subduction zones. As the hanging wall of both sides of trench systems, the Luzon Island has an elusive tectonic structure beneath. The whole southeastern Asia is believed to be a critical area for accretionary orogeny and juvenile crustal formation in Cenozoic, but the comprehensive ages of the magmatic events and the evolution of the Luzon Island are not well constrained. In order to examine the magma properties in this area, this study analyzed U-Pb ages and hafnium isotopic ratios in detrital zircons from the Luzon Island. Moreover, north of the Luzon Island, the Hengchun Peninsula is also located on the eastern side of the Manila Trench. This implies the possibility that sediments in the Hengchun Peninsula may be originated from the Luzon Island since they both sit on the Philippine Sea Plate. Hence, this study also investigated the sedimentary relationship between the two places by the comparison of detrital zircon ages and geochemical properties. Furthermore, this study also constructed a paleogeography model for the Hengchun Peninsula. Fourteen riversand samples were collected from the major rivers in the Luzon Island. The U-Pb ages of the detrital zircons show that the magmatic events mostly occurred in Eocene to Miocene and Quaternary in this area. However, some of the events in the central Luzon can be traced back to Mesozoic. Albeit the presence of old zircons, all the samples in Luzon Island show positive εHf(T) values that range from +10 to +20. These results indicate the Luzon Island is dominated by juvenile magma, and few continental material has been involved in the construction of this island. Thus, the Luzon Island could be an important locus for Asian accretionary orogenesis and Cenozoic crustal growth. In the Hengchun Peninsula, ten sandstone samples were collected in the Miocene Series. Their data demonstrate the detrital zircon ages are mostly older than Cenozoic and concentrate in Cretaceous to Jurassic, early Permian and even Precambrian. Moreover, the εHf(T) values for the samples in the peninsula are mostly negative. Since these data are significantly different from those of the Luzon Island, the results imply the Luzon Island is unlikely to be the sedimentary provenance of Hengchun. The zircon U-Pb ages of the Miocene Series in Hengchun could well correspond to the major magmatic events in southeastern China. Through the comparison with previous studies, the Miocene Series in the Hengchun Peninsula might come from Minjiang, Jiulongjiang, proto-Taiwan and a rifted continental fragment which is separated from SE China. Nevertheless, some of the younger zircons (30-15 Ma) should be originated from the mélange in the accretionary prism in the east. These sediments were scratched up from the sea floor and moved to the eastern side of the trench during the subduction and collision in southern Taiwan.
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Owusu, Agyemang Prince C. "Mesozoic detrital zircon provenance of Central Africa: implications for Jurassic-Cretaceous tectonics, paleogeography and landscape evolution." Thesis, 2018. https://researchonline.jcu.edu.au/62916/1/JCU_62916_Owusu_Agyemang_2018_thesis.pdf.
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Jurassic-Cretaceous tectonics, paleogeography and sedimentary provenance of central Africa are poorly constrained and continue to be debated. The lack of constraints on the timing and controls on late Mesozoic sedimentary basin development, drainage evolution and paleoenvironments is problematic because central Africa is well endowed with natural resources, and good understanding of these issues is fundamental to a better assessment of hydrocarbon and alluvial diamond exploration targeting. Moreover, by improving our understanding of Mesozoic strata across this vast region, we can also help to contextualise the ecological and evolutionary relationships of floras and faunas from central Africa with contemporary floras and faunas from different parts of Africa and throughout Gondwana. In particular, refining the depositional age of late Mesozoic units is key to understanding and reconstructing regional paleogeography and drainage patterns during this poorly resolved time period in Africa, which also furthers our understanding of the origins and dispersal pathways for Mesozoic, Cenozoic and modern African floras and faunas, as well as economically significant alluvial mineral resources, such as diamonds, that are important to the economies of this part of the world.
To address these issues a detailed and multifaceted sedimentary provenance analysis of 14 late Mesozoic units from seven sedimentary basins across central Africa (spanning seven different countries) was conducted. This integrated sedimentological approach incorporated sandstone petrography, paleocurrent analysis, U-Pb detrital zircon geochronology, Lu-Hf isotope and trace element geochemistry to investigate Jurassic and Cretaceous continental deposits from central Africa. The main objective was to investigate late Mesozoic sedimentary basin development, drainage evolution and provide constraints on the age of deposition, sediment source and paleofluvial drainage patterns, using core and outcrop samples from across the region; including Democratic Republic of Congo (DRC), Kenya, Angola, Sudan, Tanzania, Zimbabwe and Malawi.
Sandstone petrography and paleocurrent data indicate mixed sediment sources mainly to the south of study areas. Maximum depositional age analyses performed on U-Pb detrital zircon sample results demonstrate that most of the late Mesozoic units in central Africa are younger than previously accepted. Detrital zircon provenance analysis points to primary contributions from Neoproterozoic Pan-African Mobile Belts (e.g., Mozambique and Zambezi belts), which were probably exposed at this time are the dominant (>75%). The Lu-Hf isotope geochemistry results also show a mixed sediment provenance consisting of juvenile mantle and reworked crustal sources, which corroborates the sandstone petrography results. Western areas of central Africa (e.g. DRC and Angola) are dominated by sediments from reworked crustal sources, whereas eastern parts of central Africa (e.g. Sudan, Kenya and Tanzania) are dominated by sediments of juvenile mantle sources. The results further suggest a pattern of large ephemeral lakes in the Middle Jurassic to Early Cretaceous in the Congo and Zambezi basins, followed by the development of a large, dominantly north directed fluvial systems across central Africa in the middle Cretaceous. The results are supportive of a uniform northward continental drainage pattern throughout late Mesozoic, which supports the assertion that the paleo-Congo drainage system was likely north flowing, rather than east flowing out of the Congo Basin and into Indian Ocean as previously suggested. The results of this thesis are also supportive of the hypothesis of a major drainage divide between southern and central Africa during the late Mesozoic and the concept of a major NW trending fluvial drainage pattern into the shear zones within the Central African Rift System, although the ultimate depocentre still remains uncertain. The maximum depositional age of three Cretaceous sedimentary units, including the dinosaur-bearing Wadi Milk Formation of Sudan has been constrained. The new ages shows a generally much younger age of deposition than previous assignations, calling into question the reliability of these overly broad biostratigraphic age for these important sedimentary units.
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Siks, Benjamin Charles. "Sedimentary, structural, and provenance record of the Cianzo basin, Puna plateau-Eastern Cordillera boundary, NW Argentina." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-3449.
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The fault-bounded Cianzo basin represents a Cenozoic intermontane depocenter between the Puna plateau and Eastern Cordillera of the central Andean fold-thrust belt in northern Argentina. New characterizations of fold-thrust structure, nonmarine sedimentation, and sediment provenance for the shortening-induced Cianzo basin at 23°S help constrain the origin, interconnectedness, and subsequent uplift and exhumation of the basin, which may serve as an analogue for other intermontane hinterland basins in the Andes. Structural mapping of the Cianzo basin reveals SW and NE-plunging synclines within the >6000 m-thick, upsection coarsening Cenozoic clastic succession in the shared footwall of the N-striking, E-directed Cianzo thrust fault and transverse, NE-striking Hornocal fault. Growth stratal relationships within upper Miocene levels of the succession indicate syncontractional sedimentation directly adjacent to the Hornocal fault.
Measured stratigraphic sections and clastic sedimentary lithofacies of Cenozoic basin-fill deposits show upsection changes from (1) a distal fluvial system recorded by
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fine-grained, paleosol-rich, heavily bioturbated sandstones and mudstones (Paleocene‒Eocene Santa Bárbara Subgroup, ~400 m), to (2) a braided fluvial system represented by cross-stratified sandstones and interbedded mudstones with 0.3 to 8 m upsection-fining sequences (Upper Eocene–Oligocene Casa Grande Formation, ~1400 m), to (3) a distributary fluvial system in the distal sectors of a distributary fluvial megafan represented by structureless sheetflood sandstones, stratified pebble conglomerates and sandstones, and interbedded overbank mudstones (Miocene Río Grande Formation, ~3300 m), to (4) a proximal alluvial fan system with thick conglomerates interbedded with thin discontinuous sandstone lenses (upper Miocene Pisungo Formation, ~1600 m).
New 40Ar/39Ar geochronological results for five interbedded volcanic tuffs indicate distributary fluvial deposition of the uppermost Río Grande Formation from 16.31 ± 0.6 Ma to 9.69 ± 0.05 Ma. Sandstone petrographic results show distinct upsection trends in lithic and feldspar content in the Casa Grande, Río Grande, and Pisungo formations, potentially distinguishing western magmatic arc (Western Cordillera) sediment sources from evolving eastern thrust-belt sources (Puna‒Eastern Cordillera). In addition to growth stratal relationships and 40Ar/39Ar constraints, conglomerate clast compositions reflect distinct lithologic differences, constraining the activation of the Cianzo thrust and coeval movement on the reactivated Hornocal fault. Finally, U-Pb geochronological analyses of sandstone detrital zircon populations in conjunction with paleocurrent data and depositional facies patterns help distinguish localized sources from more distal sources west of the basin, revealing a systematic eastward advance of Eocene to Miocene fold-thrust deformation in the central Andes of northern Argentina.text
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Gardner, David William. "Sedimentology, stratigraphy, and provenance of the upper Purcell Supergroup, southeastern British Columbia, Canada: implications for syn-depositional tectonism, basin models, and paleogeographic reconstructions." Thesis, 2008. http://hdl.handle.net/1828/911.
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This thesis reports eight measured sections and >400 new detrital zircon U-Pb SHRIMP-II ages from the Mesoproterozoic (~1.4 Ga) upper Purcell Supergroup of southeastern British Columbia, Canada. The goal of my study is to constrain the depositional, tectonic and paleogeographic setting of the upper Purcell Supergroup.
Stratigraphic sections across the Purcell Anticlinorium, constructed from measured sections, reveal three syn-depositional growth faults: (1) paleo-Hall Lake, (2) paleo-Larchwood Lake, and (3) paleo-Moyie. Stratigraphic sections were combined into a fence diagram, revealing a large north-northeast trending graben bound to the east by the paleo-Larchwood Lake fault and to the west by the paleo-Hall Lake fault.
Five samples were collected for detrital zircon analysis along the eastern extent of exposed Purcell strata; one sample was collected from the western limit of strata. All samples are characterized by subordinate numbers of detrital zircons that yield Paleoproterozoic and Archean ages. Detrital zircon ages from the Sheppard Formation are dominated by 1500, 1700, 1750, and 1850 Ma grains. The overlying Gateway Formation is dominated by 1400-1450, 1700, 1850, and 1900 Ma zircon grains. The overlying Phillips, Roosville (east), and Mount Nelson formations are dominated by detrital zircon ages between 1375-1450 Ma and 1650-1800 Ma. Detrital zircon ages from the Roosville Formation (west) are dominated by 1500-1625 Ma grains.
Based on the margin perpendicular orientation of the long axis of syn-depositional grabens relative to Laurentia, and on the presence of syn-depositional aged zircons through the entire sedimentary succession, we interpret the upper Purcell Supergroup to have been deposited in a transpressional pull-apart basin setting, adjacent to a convergent/translational plate margin bound to the west by terranes now located in northeastern Australia.