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1
Bullock, Michelle. „Holocene sediments and geological history, Woolley Lake, near Beachport, South Australia /“. Adelaide : Thesis (B. Sc.(Hons)) -- University of Adelaide, Dept. of Geology and Geophysics, 1994. http://web4.library.adelaide.edu.au/theses/09SB/09sbb938.pdf.
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2
Webb, Robert H. „Late Holocene flooding on the Escalante River, south-central Utah“. Diss., The University of Arizona, 1985. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1985_248_sip1_w.pdf&type=application/pdf.
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3
Huang, Guangqing. „Holocene record of storms in sediments of the Pearl River Estuary and vicinity /“. Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21687808.
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4
Campo, Bruno <1984>. „The Pleistocene-Holocene Transition in the Po Plain (Italy): Stratigraphic Architecture and Sequence Stratigraphy from a Highly-Subsiding Basin“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7540/.
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This work focuses on the Late Pleistocene-Holocene transition in the southern Po Basin. Five areas were investigated, with the aim of unraveling the role of different allogenic factors (climate, eustacy, sediment supply) on stratigraphic architecture in the last 45 ky. The study starts from the distal portion of the basin (the coastal plain deposits) and then moves towards increasingly internal areas: the alluvial sector characterized by the Po channel belt deposits, and the mud-prone interfluvial succession between the Apenninic margin and the Po channel belt. In the coastal sector, high-resolution facies analysis, along with a well-constrained chronostratigraphic framework, led to the accurate paleoenvironmental reconstruction of the last 45 ky BP depositional history along the 93 km-long transect. It is also provided a sequence stratigraphic interpretation for the whole sedimentary succession. In the Po channel belt sector, based on 28 radiocarbon dates, facies interpretation from high-quality core descriptions and freshly-drilled continuous cores, the contrasting stratigraphic architecture of Late Pleistocene and Holocene deposits was highlighted. Changes in lithofacies and channel stacking patterns reveal the vertical superposition of amalgamated fluvial-channel sands (Late Pleistocene) and mud-dominated deposits (Holocene), with isolated fluvial-channel bodies. We also attempted to establish the link between facies architecture, sea-level fluctuations and climate changes. The 3rd study area (interfuvial succession) was selected to test a new method for paleosol identification, on the basis of geotechnical properties generated from pocket penetrometer values.
Through the reconstruction of the Biferno coastal deposits (4th study area, located ca. 300 km south of the Po Plain) we had the opportunity to document two coeval (Late Pleistocene - Holocene) coastal sedimentary successions, diverging in terms of shelf gradient and proximity to the LGM-lowstand Po Delta. The 5th study area, broadly coincides with Ferrara, was selected to show how high-resolution stratigraphic studies can be used for aquifer protection.
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McGinnis, Benjamin Adam. „Late Holocene evolution of a retrograding barrier : Hutaff Island, North Carolina /“. Electronic version (PDF), 2004. http://dl.uncw.edu/etd/2004/mcginnisb/benjaminmcginnis.pdf.
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6
Heine, Jan T. „Glacier advances at the Pleistocene/Holocene transition near Mount Rainier volcano, Cascade Range, USA /“. Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/6748.
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7
Selby, Katherine. „Late Devensian and Holocene relative sea level changes on the Isle of Skye, Scotland“. Thesis, Coventry University, 1997. http://curve.coventry.ac.uk/open/items/0e151cae-7151-0ae4-e4f3-99a45f12ce84/1.
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Five coastal sites have been studies on the Isle of Skye to investigate Late Devensian and Holocene relative sea level changes. In the field, detailed stratigraphical work, geomorphological mapping and levelling were undertaken and representatives cores were sampled. Detailed pollen and diatom analyses were undertaken in the laboratory and samples were submitted for radiocarbon assay where distinct pollen, diatom or lithostratigraphical changes were recorded. Loss on ignition analysis was also undertaken to ascertain the carbon content of the samples. The investigations have revealed that during the Late Devensian marine transgressions were experienced at two sites in southern Skye. These are thought to relate to readvances of the ice that arrested the isostatic recovery of the land, caused renewed isostatic depression and upon deglaciation, allowed marine waters to penetrate the sites. At Inver Aulavaig the transgression is thought to relate to the Wester Ross Readvance recorded in Wester Ross, Coll and Tiree and at Point of Sleat the transgression is thought to relate the Loch Lomond Readvance recorded extensively in Scotland. Relative sea level at Point of Sleat (southern Skye) then fell below an altitude of 4.13mOD at 10460+-50BP and remained low during the early Holocene until the Main Postglacial Transgression occurred. This transgression is recorded at three of the sites: at Inver Aulavaig (southern Skye) at 8850+-70BP where it had attained an altitude of at least 5.10mOD, at Peinchorran (eastern Skye) where it is thought to have been underway by 7980+-BP and attained an altitude of 4.49mOD and at Talisker Bay (western Skye) at 7790+-100BP where it had attained an altitude of -2.18mOD. At Ardmore Bay (northern Skye) it is thought that the Main Postglacial Transgression did not reach an altitude of 3.34mOD. It is possible that barrier formation at some of the sites accompanied the early states of the Mian Postglacial Transgression. It is thought that regression of the sea occurred between circa 6600 BP and circa 5400 BP and remained low until circa 4200 BP when a later rise in relative sea level took place at Peinchorran attaining a maximum altitude of 4.90mOD. A late Holocene transgression is also recorded at Point of Sleat at between circa 3800 BP and circa 2900 BP where it attained an altitude of greater than 4.13mOD and at Inver Aulavaig after circa 3200 BP where it attained an altitude of between 5.10-6.01mOD. It is unclear whether this episode of high relative sea level represents the diachronous nature of one late Holocene transgression or several fluctuations in relative sea level during the late Holocene. Following the late Holocene transgression, relative sea level fell until the present day. Comparison of the data obtained from Skye with the isobase maps and rheological models suggests that the isobases for the Main Lateglacial Shoreline (Firth et al., 1993) show a good fit in age and altitude but the rheological model of Lambeck (1993b) for 10500 BP requires modification. The isobases for the Main Postglacial Shoreline appear to lie circa 4m too high for the sites studied on Skye and the isobases produced for a late Holocene shoreline appear to be greatly in error (Firth et al., 1993). It is possible that the build up of ice during the Loch Lomond Stadial may have had a greater effect on crustal movements than previously thought and this may account for discrepancies identified in the isobase maps. The study of isolation basins and back-barrier environments has allowed an assessment of their potential in recording relative sea level changes. The use of isolation basins in areas devoid of estuarine sedimentation has been particualrly demonstrated. The vegetation reconstruction undertaken, suggests that variations do occur in coastal locations compared to sites further inland, although these are subtle. The dates obtained for the increase in taxa such as 'Corylus avellana' and 'Alnus' and the recording of anthropogenic indicators on the vegetation, agree with those previously obtained for Skye. The use of pollen analysis in verifying the radiocarbon dates obtained, particualrly for the Late Devensian, has been recognised and, combined with diatom analysis, has provided a comprehensive database from which to reconstruct past relative sea levels.
8
Lee, Ting Jennifer. „Holocene evolution of a hypersaline lake Lagkor Tso, western Tibet /“. Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B39634140.
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Burbidge, Susan M. (Susan Margot) Carleton University Dissertation Earth Sciences. „Holocene environmental history of lake Winnipeg; thecamoebians and stable lead isotopes“. Ottawa, 1997.
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Prater, Alexa Brianne. „Stratigraphic and microfossil evidence of repeated late Holocene tsunami inundation at Sitkalidak Island, Alaska“. Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/105104.
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Seismic hazard models for Alaska require estimates of the size and frequency of prehistoric megathrust earthquakes. However, observations that place limits on the size of subduction paleoearthquakes along the Alaska-Aleutian subduction zone are scarce. To help place bounds on the along-strike extent of prehistoric Alaska-Aleutian subduction ruptures, we present stratigraphic and microfossil evidence of repeated tsunami inundation over the last ~400 years at Sitkalidak Island, located 0.5 km off the coast of south-central Kodiak Island. Peat cores collected from an estuary in southern Sitkalidak Island reveal three anomalous, laterally continuous sand beds with sharp upper and lower contacts preserved within a coastal peat sequence. The microfossil and lithostratigraphic characteristics of the sand beds, including the presence of anomalous marine planktonic diatoms, high fragmentation of diatoms, and upward fining sand sequences, indicate high-energy marine incursions consistent with tsunami inundation. Radiocarbon dating constrains the deposition of the sand beds to AD 1964, AD 1788, and ~400 cal yr B.P. The peat core stratigraphy and dates are consistent with tidal wetland stratigraphic records observed at sites ~90 km to the west at Sitkinak Island, and ~80 km to the east at Middle Bay, Kodiak Island. Diatom results from Sitkalidak Island suggest decimeter-scale subsidence during the deposition of the 1964 CE and 1788 CE sand bed. Deformation concurrent with the 1964 and 1788 ruptures along with the presence of a sand bed associated with the ~400 cal yr BP rupture at Sitkalidak help better define the western and eastern rupture limits, and thus the permissible maximum magnitudes, of past Alaska-Aleutian subduction zone ruptures.Master of Science
The Alaska-Aleutian subduction zone experiences frequent great earthquakes over magnitude 8 which often produce far-reaching tsunamis. Seismic hazard models that help coastal communities predict and prepare for future hazards require estimates of the size and frequency of prehistoric earthquakes. Data for prehistoric earthquake events in the western region of the subduction zone is scarce. To help address the lack of prehistoric data and understand the rupture path and magnitude of past Alaska-Aleutian earthquakes, we present stratigraphic and microfossil evidence of repeated tsunami inundation over the last ~400 years at Sitkalidak Island, located 0.5 km off the coast of south-central Kodiak Island, Alaska. Sediment cores collected from a marsh in southern Sitkalidak Island record three laterally continuous sand beds with sharp stratigraphic contacts preserved within a coastal peat. Diatom microfossil and grain-size characteristics of the sand beds indicate high-energy marine incursions consistent with chaotic tsunami inundation. Radiocarbon dating places the age of sand bed deposition to AD 1964, AD 1788, and ~400 cal yr B.P. The sediment core stratigraphy and dating correlates well with sites investigated ~90 km to the west and ~80 km to the east. Diatom results from Sitkalidak Island point to small, decimeter scale coseismic subsidence during the deposition of the AD 1964 and AD 1788 sand beds. Land-level change concurrent with the 1964 and 1788 earthquakes along with the presence of a sand bed associated with the ~ 400 cal yr B.P. earthquake found at Sitkalidak Island help better define the earthquake rupture limits and maximum magnitudes of past Alaska-Aleutian subduction zone earthquakes.
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Gouw, Marc. „Alluvial architecture of the Holocene Rhine-Meuse delta (the Netherlands) and the Lower Mississippi Valley (U.S.A.) /“. Utrecht : Koninklijk Nederlands Aardrijkskundig Genootschap, Faculteit Geowetenschappen Universiteit Utrecht, 2007. http://www.loc.gov/catdir/toc/fy0803/2008400359.html.
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Brown, Kendrick Jonathan. „Late quaternary vegetation, climate, fire history, and GIS mapping of Holocene climates on southern Vancouver Island, British Columbia, Canada“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ52755.pdf.
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Lee, Ting Jennifer, und 李婷. „Holocene evolution of a hypersaline lake: Lagkor Tso, western Tibet“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B39634140.
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Gates, Edward Breed. „The Holocene Sedimentary Framework of the Lower Columbia River Gorge“. PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/4801.
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The Columbia River is the largest fluvially dominated estuary in the Pacific Northwest, yet the Holocene transgressive fill of this system has not previously been studied. Nearly 1500 industry borehole and water well records in the lower Columbia River basin (LCRB) were analyzed. These records document the sedimentary infilling of the lower 120 miles of the drowned river valley that occurred during the Holocene marine transgression (10-0 ka) . Of particular importance is a key stratigraphic marker horizon of volcanic tephra that has been identified throughout the LCRB. INAA was used to determine the geochemical composition of the target tephra layer. The tephra geochemistry was then compared to geochemical data from potential Cascade source volcanos to determine whether the tephra layers are geochemically related, and the possible age and source of the tephra. The geochemical comparisons indicate that the suspect tephra horizon was derived from the climax eruption of Mount Mazama approximately 6845 years ago. Cross-sections have been constructed that record the lateral and longitudinal depositional development of the river basin. Sediment grain size distribution data have also been compiled and shows that grain size distribution does not change with respect to subsurface elevation within the LCRB. The results indicate that the LCRB has been dominated by fine sand deposition throughout the Holocene period, and silt and clay sized fractions were bypassed through the system to be deposited offshore. A total volume of 74.6 km3 of sediment has accumulated in the basin since the time of the catastrophic floods 12,700 years ago. Sediment volume analysis was used to predict past fluvial sediment supply rates and sediment retention. The volume of sediment deposition from early to late Holocene time has decreased by a factor of 2.4. Sedimentation rates in the basin are estimated from a basin isopach of the Holocene fill and from an extrapolated sediment sea-level curve. Basin sedimentation rates ranged from 12. 6 mm/yr-1 for the early Holocene to 2. 5 mm/yr-1 for the late Holocene period. This factor of 5 decrease in the sedimentation rate also indicates that the Columbia River bypassed much of its fine grained fraction through to the marine environment during the mid-late Holocene.
15
Freeman, Andrea Kelly Lee. „Middle to late holocene stream dynamics of the Santa Cruz River, Tucson, Arizona : implications for human settlement, the transition to agriculture and archaeological site preservation“. Diss., The University of Arizona, 1997. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1997_349_sip1_w.pdf&type=application/pdf.
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Gudmundsson, Hjalti Johannes. „Holocene glacier fluctuations and tephrochronology of the Öræfi district, Iceland“. Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/15756.
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The aims of this thesis are to refine the tephrochronology of the Öræfi district, SE Iceland and assess the Holocene glacier fluctuations of the Öræfajökull ice cap. The pattern and timing of glacier fluctuations are determined using glacial geomorphology and tephrochronology, and the implications for palaeoclimate are assessed. Iceland is important to the study of global and regional climatic change because it is located close to both the marine and atmospheric Polar Fronts widely regarded as the key factors in the climate of the North Atlantic region. Six outlet glaciers were studied: Svinafellsjökull, Virkisjökull, Kotárjökull and Kviárjökull originating from the Öræfajökull ice cap and Skaftafellsjökull and Morsárjökull originating from the Vatnajökull ice cap. A long history of glacier fluctuations were found with a similar temporal pattern of glacier oscillation between the outlets of Vatnajökull and Öræfajökull. A maximum of eight advances have been identified. The oldest advance is inferred to date from the maximum of the last Glaciation ca. 18000 yrs BP. The first advance in the Holocene occurred ca. 9700 BP during a still-stand of the last Termination. The onset of the Neoglaciation occurred between 6000 BP and 4600 BP with an expansion of all of the studied glaciers. Subsequent smaller advances have been dated to ca. 3200 BP, ca. 1800 BP, ca. 700 BP, ca. 200 BP and ca. 80 BP. The most significant movement of the Polar front during the Holocene is likely to have occurred around 5000 BP, and, as a consequence, an estimated temperature cooling of ca. 2.5°C took place in Iceland, perhaps the greatest cooling since the last Termination. Within the broad pattern of change, glaciers in the study area show variability which represents local precipitation patterns, contrasting topography and change in glacier process. In this thesis a total of 22 silicic tephra layers are identified from over 90 profiles in the study area. The majority of these layers are dated to the latter part of the Holocene. Three silicic tephras were deposited during historical time (post 900 AD) namely, Vö ca. 900AD,HI104 and Ö1362. The Vö ca. 900 AD and the H1104 tephras are located for the first time. Specific prehistoric (pre 900 AD) tephras identified include Hekla-Ö, Hekla-4 and Hekla-S. The tephrochronology of the Öræfi district is also used to assess the eruption history of the Öræfajökull stratovolcano during the Holocene. Prehistoric eruptions are dated to ca. 9200 BP, ca. 6500 BP(?), ca. 4700 BP, ca. 2800 BP and ca. 1500 BP. Jökulhlaups accompanied the eruptions of 1727 AD, 1362 AD and ca. 1500 BP and are likely to have followed older eruptions of the volcano. A strong relationship occurs between volcanic activity of the Öræfajökull stratovolcano and the pattern of glacier fluctuations. This is explained as a response to isostatic crustal adjustment during ice cap growth and decay, and indicates a general relationship between volcanic activity and climate change.
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Bleakley, Nerida Lynn. „Late holocene palaeoecology of Taynaya Bay : the relationships between diatom assemblages and sediment composition in Antarctic coastal environments, and their response to regional climate change. Volume 1“. Monash University, School of Geography and Environmental Science, 2003. http://arrow.monash.edu.au/hdl/1959.1/5784.
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Mok, Ka-man, und 莫嘉敏. „[Delta]¹³C as a palaeo-environmental indicator in a sediment core fromHong Kong“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49770470.
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A study of marine palaeo-landscape development through a sediment core in the western Hong Kong waters has been carried out in this project as the sedimentation record could reflect the environmental changes during the Holocene period.
The objectives of this study was to reveal the influences of Holocene post-glacial sea-level fluctuations and the monsoonal freshwater discharge changes to the sedimentation processes in the mouth region of the Pearl River Estuary. These are the two important factors which shape the palaeo-landscape development.
Data has been obtained from a ground-truthing vibrocore to 35m below the seafloor at the south of the Shek Pik Reservoir, south Lantau Island. The sediment core was subsampled for elemental analysis to study the sources of the organic carbon by use of stable carbon isotope ratio (Ϭ13C) and for particle size analysis to reveal the energy state of the sedimentary environment. Shell fragments were chosen for radiocarbon analysis to construct the core chronology and marine seismic profiles were obtained to present the sub-bottom geological layers.
The data is presented in the form of graphs and tables in showing the sediment changes along the core in different period of time. The data has been interpreted in relation to the knowledge of post-glacial sea-level rise and the proposed model of the Pearl River Estuary evolution from previous studies. Comparison is also made with other sediment cores around the Lantau Island to reveal the regional palaeo-environmental changes in the Holocene period.
It is concluded that the sediment core has revealed four major phases of environmental change which is in general agreement with the previous studies except this data set has also shown a few localized climatic events in the mid-Holocene period. The sea-level low stand in the late Pleistocene had incised a network of drainage system on the exposed continental shelf which is the north South China Sea in present time. The rapid rising sea-level by Melt Water Pulse 1B filled the palaeo-valleys with alluvium deposits from 10600 to 9000 cal. yr BP at high sedimentation rate and the East Asian Monsoon was strengthened from 8800 to 5500 cal. yr BP as shown by the freshwater organic carbon deposited in the marine environment. Unconfined deposition occurred when the sediments spilled out of the palaeo-valleys and slowly covered the basin in stable sea-level and low hydrodynamic conditions.published_or_final_version
Applied Geosciences
Master
Master of Science
19
Gouw, Marc Jean Pierre. „Alluvial architecture of the Holocene Rhine-Meuse delta (The Netherlands) and the Lower Mississippi Valley (U.S.A.) /“. Utrecht : Koninklijk Nederlands Aardrijkskundig Genootschap [u.a.], 2007. http://www.loc.gov/catdir/toc/fy0803/2008400359.html.
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Margotta, José. „Stratigraphic architecture and sedimentary evolution of the Holocene deposits in the French Flemish coastal plain, Northern France“. Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10012/document.
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Cette thèse a pour objectif la reconstitution des étapes ayant conduit au remplissage sédimentaire de la plaine maritime flamande française au cours de l'Holocène. L'approche utilisée a consisté en l'utilisation conjointe de bases de données de forages, de sondages et d'observations réalisées au cours de cette étude et, pour la première fois de données issues d'une campagne de sismique à très haute résolution dans les voies navigables de la plaine côtière. La relecture des données lithologiques au regard de nos propres observations permet de définir précisément les faciès de remplissage de la plaine. Les données lithologiques, minéralogiques (argiles) et micropaléontologiques (foraminifères et pollens) sont à la base de la reconnaissance de 5 faciès sédimentaires représentatifs du remplissage. Ces faciès ont été interprétés en assemblages de faciès de dépôt. Ceux-ci ont été regroupés en 3 unités caractérisant l'évolution verticale des conditions de dépôt. A la base une plaine alluviale, puis une série estuarienne dominée par la marée et une série d'estran tidal. La première unité correspond à des dépôts tardi-pléistocènes, tandis que les deux autres représentent les dépôts holocènes remplissant la majorité de l'espace d'accommodation disponible. Une série de 10 profils au travers de la plaine maritime permet de comprendre la distribution et la géométrie de ces unités ainsi que l'organisation des faciès sédimentaires. L'arrangement stratigraphique met en évidence les interactions entre le taux de remontée du niveau marin et les conditions hydrodynamiques caractérisées par un régime macrotidal et influencées localement par la houle. Notre étude permet de mieux comprendre le fonctionnement de ce type de zone basse et ouvre des perspectives de modélisation de scénarios futurs d'évolutionThe aim of this study is to reconstruct the evolution of the Holocene deposits along the French Flemish Coastal Plain. This approach is achieved combining available and newly dataset from boreholes, cores descriptions and, for the first time in this plain, the interpretation of VHR seismic profiles on the coastal plain waterways. The study of lithology, micropaleontological assemblages (foraminifera and pollen analyses) and clay mineralogy provides the basis to recognize five sedimentary facies as representative of the Holocene infill. These sedimentary facies were interpreted as depositional facies assemblages in accordance to their depositional features. Depositional facies were grouped in three sedimentary units that better define the depositional environment. From base to top, the units are: alluvial plain, tide-dominated estuary and tidal flats. The alluvial plain consists of late Pleistocene deposits while estuarine and tidal flats units represent the Holocene deposits covering almost the whole available accommodation space. Distribution and geometry of these sedimentary units and their internal architecture of depositional facies were observed from ten cross-sections that cover most of the coastal plain. Stratigraphic arrangement shows the interaction of the Holocene sea-level rise and the coastal hydrodynamic conditions, dominated by the macrotidal regime and influenced by waves action, as the main factors that ruled the sedimentation of the area. This study opens new possibilities to better understand the coastal processes that acted in this lowland, as well as serves as a basis for future studies or modelling possible future scenario
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Hazard, Colby. „Validity of Holocene Analogs for Ancient Carbonate Stratigraphic Successions: Insights from a Heterogeneous Pleistocene Carbonate Platform Deposit“. BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5496.
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Observations of modern carbonate depositional environments and their accompanying depositional models have been used for decades in the reconstruction and interpretation of ancient carbonate depositional environments and stratigraphic successions. While these Holocene models are necessary for interpreting their more ancient counterparts, they inherently exclude important factors related to the erosion, diagenesis, and ultimate preservation of sediments and sedimentary structures that are ubiquitous in shallow marine carbonate environments. Andros Island, Bahamas is an ideal location to examine the validity of Holocene conceptual models, where geologically young (Late Pleistocene) limestones can be studied immediately adjacent to their well-documented modern equivalents. For this study, two 3D ground-penetrating radar (GPR) datasets (200 MHz and 400 MHz) were collected at a schoolyard in northwest Andros. These surveys reveal the geometries and internal characteristics of a peloidal-oolitic sand wave and tidal channel in unprecedented detail. These two prominent features are underlain by low-energy lagoonal wackestones and packstones, and are bordered laterally to the northwest by wackestones-packstones intermixed with thin sheets of peloidaloolitic grainstone. A deeper radar surface is observed at approximately 6 m depth dipping gently to the west, and is interpreted to be a karstified exposure surface delineating the base of a complete depositional sequence. Interpretation of the 3D radar volumes is enhanced and constrained by data from three cores drilled through the crest and toe of the sand wave, and through the tidal channel. This study is the first of its kind to capture the complex heterogeneity of a carbonate depositional package in three dimensions, where various depositional environments, sedimentary structures, and textures (mudstone to grainstone) have been preserved within a small volume.The results from this study suggest that the degree of vertical and lateral heterogeneity in preserved carbonate successions is often more complex than what can be observed in modern depositional environments, where sediments can generally only be observed in two dimensions, at an instant in time. Data from this study demonstrate the value of using two overlapping GPR datasets at differing resolutions to image the internal characteristics of a complete carbonate depositional package in three dimensions. From these datasets, a depositional model similar to other Holocene and Pleistocene carbonate depositional models is derived.
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Wittmer, Jacalyn M. „Quantitative approaches and applications to the sequence stratigraphy and biodiversity of Pleistocene – Holocene mollusk communities from the Po plain, Italy and San Salvador Island, the Bahamas“. Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/56637.
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The following chapters presented here use modern ecological data and modern marine systems to evaluate past marine depositional settings and the preservation potential of various environments in the geological record.
While the chapters in this dissertation vary in terms of study area, sedimentary systems (carbonate vs. siliciclastic), depositional environment, and organisms, all projects are based on developing and using quantitative models to evaluate the present as a means for understanding the past.
Chapter one focuses on the preservation potential of rocky intertidal environments. The rocky intertidal zone is one of the most poorly preserved fossil-rich environments in the geological record. However in most coastal marine habitats today, it is one of the most diversity rich environments. Chapter one also focuses on the analytical advantages of hierarchical sampling of gastropod communities across San Salvador Island, the Bahamas to quantify community and species level preservation potential in rocky shore environments. Chapters two and three are based on the fossil-rich sedimentary deposits from the Po coastal plain in northeastern Italy. These deposits have been widely studied in terms of their sedimentology and stratigraphy, resulting in a highly resolved sequence stratigraphic architecture. The integration of sequence stratigraphy with paleobiology can enhance our understanding of spatiotemporal biotic patterns recorded in the fossil record. Used in conjunction with the highly-resolved stratigraphic framework, biotic patterns can be used to assess depositional cycles and bathymetry through time. Chapter two integrates sequence stratigraphic patterns and paleoecological data to develop bathymetric models across fossiliferous marine successions of the Po coastal plain, Italy. Chapter three evaluates the modern ecological dataset used to derive the bathymetric models. The last chapter also explores water depth distribution for selected taxa recorded in the Quaternary sediments and observed in present-day habitats. The dissertation research explored here demonstrates that modern ecological systems are essential to evaluating past geologic events. Through direct observation and quantitative analysis, I have learned that modern and fossil communities behave differently depending on environment (e.g. energy, salinity, water depth, etc.). These variables affect the distribution of living organisms today and through my research, delineate fossil distributions through time. With these observations, new questions have arisen about the latitudinal variability of rocky intertidal fossil preservation and extrapolating the quantitative bathymetric models to deeper time intervals. These questions will lead to future endeavors and pointedly add to the field of geology and stratigraphic paleobiology.Ph. D.
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Callefo, Flávia 1983. „Análise tafonômica e paleoecológica de estruturas associadas a comunidades microbianas holocênicas e permianas“. [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287739.
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Orientador: Fresia Soledad Ricardi Torres BrancoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: Esteiras microbianas são estruturas organossedimentares laminadas, desenvolvidas a partir do acréscimo de lâminas de sedimentos aprisionados através do metabolismo de microrganismos, que induzem a precipitação de carbonato. Microbialitos são depósitos organossedimentares formados pela interação de microrganismos com sedimentos detríticos, através dos processos de trapeamento e aglutinação dos grãos e minerais. Esta pesquisa apresenta os resultados obtidos com o estudo tafonômico e paleoecológico de estruturas desenvolvidas por atividade de microrganismos, como estromatólitos, microbialitos e esteiras microbianas, com o intuito de comparar os resultados e traçar similaridades e diferenças nas relações ecológicas e ambientes de formação . Foram utilizados modelos recentes (Holoceno), como a Lagoa Salgada e Lagoa Pitanguinha, RJ, para compreender modelos fósseis (Permiano), afloramentos em Taguaí e Santa Rosa do Viterbo, SP. A metodologia se constituiu em análise de sedimentos associados, petrografia, análises composicionais (como MEV/EDS e Espectroscopia Raman) e estudo de campo. Foram levados em consideração os aspectos ambientais e biota contemporânea ao crescimento e desenvolvimento dos microbiais. As principais conclusões obtidas foram que os ambientes apresentam similaridades com relação a biota desenvolvida, bem como as relações ecológicas que estas mantinham com as comunidades microbianas responsáveis pelo desenvolvimento dos microbialitos e esteiras microbianas. O ambientes de crescimento das estruturas eram marinhos de águas rasas e hipersalinas, com o clima quente e alta taxa de evaporação. A alternância de eventos de tempestades e águas calmas, com posterior período de calmaria no qual foi possível o desenvolvimento de esteiras microbianas foram evidenciados no afloramento de Taguaí e na Lagoa Pitanguinha. Os microbialitos recentes da Lagoa Salgada sofreram maior influência de atividade de predação e herbivoria por parte de invertebrados, o que pode ter sido um fator relevante para a limitação do crescimento destas estruturas em comparação com aquelas existentes em Santa Rosa do Viterbo
Abstract: Microbial mats can be defined as laminated organosedimentary structures developed from the addition of laminaes of sediments trapped trough microorganisms metabolism, which leads to carbonate precipitation. Microbialites are organosedimentary deposits generated by the interation between microorganisms and detritic sediments through trapping and agglutination of minerals and grains play a key role. This research present the results of taphonomic and paleoecological studies from of structures developed by the activity of microorganisms such as microbialites, stromatolites and microbial mats aiming to comparison between the results obtained and to map similarities and differences on the ecological relations and formation environments. Recent models such as Salgada Lagoon and Pitanguinha Lagoon (Holocene), both located on Rio de Janeiro, were used to understand permian fossils models, outcrops located in Taguaí and Santa Rosa do Viterbo/SP. The methodology was based on the analysis of associated sediments, petrography and compositional analysis (MEV/EDS and Raman Spectroscopy) besides field studies. Aspects such as recent environments and biotas were considered to the analysis. The main conclusions were that the environments present similarities based on the development of the biotas as well as the ecological relations which those developed within the microbial communities responsible for the development of the microbialites and microbial mats. The growth environments of the structures were classified as shallow marine hypersaline waters, with warm weather and high evaporation rates. There was an alternation between storm events and calm waters. The growth of microbial mats became possible when the waters were predominantly calm evidenced by the outcrops from Taguaí and Pitanguinha Lagoon. The recent microbialites from Salgada Lagoon had a greater influence by activities from predators and herbivorous organisms such as invertebrates, which may be a relevant factor for the limitation growth of these structures when compared with those founded at Santa Rosa do Viterbo
Mestrado
Geologia e Recursos Naturais
Mestra em Geociências
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Bridgeman, Jonathan G. „Understanding Mississippi Delta Subsidence through Stratigraphic and Geotechnical Analysis of a Continuous Holocene Core at a Subsidence Superstation“. Thesis, Tulane University School of Science and Engineering, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10789629.
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Land-surface subsidence can be a major contributor to the relative sea-level rise that is threatening many coastal communities. Loosely constrained subsidence rate estimates across the Mississippi Delta make it difficult to differentiate between subsidence mechanisms and complicate modeling efforts. New data from a nearly 40 m long, 12 cm diameter core taken during the installation of a subsidence monitoring superstation near the Mississippi River, southeast of New Orleans, provides insight into the stratigraphic and geotechnical properties of the Holocene succession at that site. Stratigraphically, the core can be grouped into four units. The top 12 m is dominated by clastic overbank sediment with interspersed organic-rich layers. The middle section, 12–35 m, consists predominately of mud, and the bottom section, 35–38.7 m, is marked by a transition into a Holocene-aged basal peat (~11.3 ka) which overlies densely packed Pleistocene sediment. Radiocarbon and OSL ages are used to calculate vertical displacement and averages subsidence rates as far back as ~3.5 ka, yielding values as high as 8.0 m of vertical displacement (up to 2.34 mm/yr) as obtained from a transition from mouth bar to overbank deposits. We infer that most of this was due to compaction of the thick, underlying mud package. The top ~80 cm of the core is a peat that represents the modern marsh surface and is inducing minimal surface loading. This is consistent with the negligible shallow subsidence rate as seen at a nearby rod-surface elevation table–marker horizon station. Future compaction scenarios for the superstation can be modeled from the stratigraphic and geotechnical properties of the core, including the loading from the planned Mid-Barataria sediment diversion which is expected to dramatically change the coastal landscape in this region.
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Sloss, Craig R. „Holocene sea-level change and the aminostratigraphy of wave-dominated barriers estuaries on the southeast coast of Australia“. Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060306.154507/index.html.
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Metcalfe, Elisabet Joan. „Late-glacial through Holocene Stratigraphy and Lake-level Record of Rangely Lake, Western Maine“. Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/MetcalfeEJ2007.pdf.
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Jones, Nadia Sittara. „Investigating the Holocene History of Eliot Glacier, Mount Hood, Oregon“. PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/618.
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This research documents the Holocene glacial history of Mount Hood, Cascade Mountains, Oregon by analyzing a set of three lateral moraines abutting Eliot Glacier, the largest glacier on the mountain. This study seeks to: 1) establish the relative ages of these lateral moraines and 2) determine if these features represent distinct glacial advances. The hypothesis is that the lateral moraines for Eliot Glacier represent three distinct periods of glacial advance based on their position relative to the current glacier and other diagnostic indicators. Soil profiles of three positions (shoulder, backslope, and footslope) on the distal side of each lateral moraine were described in the field and samples were taken from each horizon for laboratory analyses of pH and particle size. The results of the soil analysis show that the soils developing on the moraine closest to the current glacier are poorly developed and significantly younger than the other two features. The closest moraine likely dates to the Little Ice Age (600-150 YBP) and has soils with an A/C profile and a classification of Andic Cryopsamment. The soils on the middle and furthest moraines from the glacier are similar in the profile sequence (Andic Haplocryepts). Silt bulges were noted in the mid-slope pits. The furthest moraine has deeper horizons and more color development than the middle moraine. Ash layers were found in the backslope soil profile (36-51cm deep) on the middle moraine. Additional lab testing confirms the ash layers originated from Mount Hood, but no date can be assigned. The eruptive history of Mount Hood points to the Timberline eruptive period (1,500 YBP) as a likely candidate for one of the ash deposits. This evidence suggests the middle moraine was actively forming during this period and is intermediate in age between the furthest moraine and the Little Ice Age Moraine; hence, this sequence of moraines indicates three distinct periods of glacial advance in the Neoglacial.
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Chiti, Bernardo. „Holocene fluvial and marine influences and settlement interactions in the lower Ribble Valley, Lancashire, U.K“. Thesis, University of Stirling, 2004. http://hdl.handle.net/1893/1805.
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The evolution of the lower course and estuary of the river Ribble (Lancashire, U.K.) during the Holocene is the object of study, along with the history of sediment fluxes in them and their influence on past human settlements. Investigation of the valley floor geomorphology and terrace fill stratigraphy and sedimentology, as well as palaeoecological analysis and a number of 14C essays, allowed the reconstruction of Late Pleistocene and Holocene alluvial history and chronology of a reach at the transition point between fluvial and estuarine influences; the archaeological evidence is evaluated in this context. Alluviation and incision cycles led to the formation of four river terraces. The oldest terrace, rich in coarse-grained materials, seems to be of Pleistocene age. 14C dating on the second terrace would point to an Earliest Holocene or Younger Dryas age; the fill, however, comprises abundant fine-grained overbank sediments. Large parts of the unit were reworked during a phase of lateral channel activity that occurred prior to ca. 8900 cal BP; between then and ca. 6900 cal BP the river underwent meander cut-offs, after which limited lateral activity occurred. New alluviation occurred around 4700 cal BP, possibly related to the aggradation of the third terrace, though its fill is only certainly known, from archaeological evidence, to be of pre-Roman age. Channel size increase occurred by the time the terrace was deposited. The fill features abundant clayey sediments; it was incised at or after the end of the Roman period. The last terrace was deposited in the late first millennium AD mainly as overbank silts, and has since been incised again. Fluvial response appears mainly related to climate changes, river activity corresponding to shifts to wetter, cooler climate. Human action likely enhanced fluvial response in the historical period, leading to post-Roman incision and deposition. There seems to be a good connection between sediment production in the catchment and deposition downstream. Local factors also show a major importance in determining river response. Early Holocene fluvial history finds no match in other Northern English rivers; a different response to the same climate changes is apparent, possibly related to differences in sediment supply conditions. No clear evidence is found supporting an influence of sea-level change on river processes. On the other hand, it appears plausible river sediment input has a driving influence in enhancing or causing minor regressions recorded on the estuary. The conditions existing in Roman times could have allowed access from the sea to the Roman sites at the upper end of the Ribble estuary and by its North shore; a relative sea-level minimum could have caused a shift of focus in naval traffic from the former to the latter site.
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Hornsby, Kristofer Tyler. „Constraining the Holocene Extent of the Northwest Meers Fault, Oklahoma Using High-Resolution Topography and Paleoseismic Trenching“. PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3890.
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The Meers Fault (Oklahoma) is one of few seismogenic structures with Holocene surface expression in the stable continental region of North America. Only the ~37 km-long southeastern section of the ~55 km long Meers Fault is interpreted to be Holocene-active. The ~17 km-long northwestern section is considered to be Quaternary-active (pre-Holocene); however, its low-relief geomorphic expression and anthropogenic alteration have presented difficulties in evaluating the fault length and style of Holocene deformation. We reevaluate surface expression and earthquake timing of the northwestern portion of the Meers Fault to improve fault characterization, earthquake rupture models, and seismic hazard evaluations based on fault length. We use a combination of airborne lidar (0.5--2 m-resolution), historical aerial photos, and new balloon-based photogrammetric (Structure from Motion) topography (0.25--0.5 m-resolution) collected in this study to analyze and characterize the fault scarp and local fault zone geomorphology. In the northwest, complex surface deformation includes fault splays, a left step, subtle monoclinal warping, and a minor change in fault strike. The fault is evident in the landscape as linear escarpments, incised channels on the up-thrown side of the scarp, and closed depressions on the downthrown side. I use topographic profiles, measured perpendicular to the fault scarp to show that the northwest scarp is characterized by decimeter surface offsets. Where the fault traverses the Post Oak Conglomerate the fault zone width rarely exceeds 25 m, in the Hennessey Shale I document an increase in fault zone width with deformation occurring over 20 m to 115 m. I further examined the northwest section of the fault in a paleoseismic excavation where weathered Permian Hennessey Shale and a ~1--2 m-thick veneer of Holocene alluvial deposits have been folded and warped during three surface-folding earthquakes. In an adjacent stream exposure these units are also faulted near the ground surface. Paleoearthquake age modeling (Oxcal) constrained by accelerated mass spectrometry (AMS) dating of detrital charcoal and optically stimulated luminescence (OSL) dating of sandy alluvial beds indicates two earthquakes occurred since ~6152-5550 cal. years BP and one possibly older event along the erosional unconformity along the Hennessey Shale bedrock. This analysis lengthens the Holocene extent of the Meers Fault by ~6 km, to ~43 km, and extends the paleoseismic record of the Meers Fault to ~9598 cal. years BP. These data will improve fault-rupture and earthquake recurrence models used for seismic hazard analysis of the Meers Fault.
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Leoncini, Carlotta. „Stratigraphic study and analysis of the barchan dunefield of the Laguna coastal zone in Santa Catarina, Brazil“. Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7948/.
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The association of several favorable factors has resulted in the development of a wide barchan dune field that stands out as a fundamental element in the coastal landscape of southern Santa Catarina state in Brazil. This original ecosystem is being destroyed and highly modified, due to urbanization. This work identifies and discusses its basic characteristics and analyzes the favorable factors for its preservation, in the foreseen of both a sustainable future and potential incomes from ecotourism. The knowledge of the geologic evolution allows to associate this transgressive Holocene dunes formation to more dissipative beach conditions. Spatial differences on morphodynamics are related to local and regional contrasts in the sediment budget, with an influence on gradients of wave attenuation in the inner shelf and consequently with influence in the level of coastal erosion. The link between relative sea level changes and coastal eolian sedimentation can be used to integrate coastal eolian systems to the sequence stratigraphy model. The main accumulation phase of eolian sediments would occur during the final transgressive and highstand systems tracts. Considering the global character of Quaternary relative sea level changes, the Laguna transgressive dune field should be correlated with similar eolian deposits developed along other parts of the Brazilian coast compatibles with the model of dunefield initiation during rising and highstand sea level phases.
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Pierce, Lila Eve Rose. „Poverty Shelf, New Zealand from the Holocene to Present: Stratigraphic Development and Event Layer Preservation in Response to Sediment Supply, Tectonics and Climate“. W&M ScholarWorks, 2012. https://scholarworks.wm.edu/etd/1539616809.
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The small, high sediment yield Waipaoa River is located on the tectonically active, mountainous Poverty Margin on the east coast of the North Island, New Zealand. In contrast to sedimentary sequences on passive margin shelves, active margins, such as the Poverty Margin, can preserve continuous records of changing geological and environmental conditions at the land-sea interface during rapid sea-level rise. Two subsiding mid-shelf basins on the Poverty Shelf contain thick transgressive sequences which provide a record of evolving river, climate, landscape, and oceanographic conditions since the Last Glacial Maximum (LGM). This dissertation investigates the stratigraphic development of Poverty Shelf, including event layer preservation, over the last ∼14ka using geochemical proxies and physical properties analyses of the sedimentary record. The work herein was conducted under the auspices of the MARGINS Source-to-Sink program, a multi-national, interdisciplinary study focused on understanding sediment routing, transformation and fate through the Waipaoa Sedimentary System (WSS) from catchment sources to final sinks on the adjacent Poverty Shelf and Slope. A suit of five giant piston cores and eight box cores were retrieved from Poverty Shelf during two cruises to address long (Holocene) and short (modern) timescales, respectively, of deposition. Geochronological, geochemical and sedimentological profiles from the giant piston cores are used to reconstruct the processes that influenced shelf infilling during this critical period of recent earth history. Accumulation rate analyses from high-resolution radiocarbon profiles and tephrachronology, along with X-radiographic facies analysis, enable tracking of rapidly shifting loci of deposition from the slope to mid-shelf depocenters. Grain size profiles and delta13C values reveal sympathetic changes that track the waxing and waning influences of sediment supply via the Waipaoa River as sea level rose to maximum flooding at ∼7ka, subsequent Poverty Bay shoreline reorganization and changing shelf accommodation, and, in the last ∼1ka, a strong anthropogenic signal. Imprinted upon this record is evidence for temporal and spatial changes in event layer frequency and type throughout the Holocene. Event layers may be produced by extreme and episodic storms, floods, earthquakes and other perturbative events that punctuate background marine sedimentation with large additions of terrestrial sediment. Event layers can be identified by unique textural and geochemical characteristics. An event layer, likely emplaced via hyperpycnal flow, attributed to Cyclone Bola (1988), the most severe modem cyclone on record in this location, serves as a modem benchmark for other storm events in the Poverty Shelf records. Examination of X-radiographs and lithostratigraphy, textural and isotopic variability reveal that the Poverty Shelf stratigraphic record preserves evidence of exceptional event sedimentation in the past and present that can be distinguished from shifts in supply, transport, and accumulation of sediments due to longer-time scale perturbations related to climate, sea level, and tectonics. A period of increased fidelity of the event record in the mid-Holocene is observed associated with increased accommodation within rapidly flooded depocenters.
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Schlichting, Robert B. „Establishing the Inundation Distance and Overtopping Height of Paleotsunami from the Late-Holocene Geologic Record at Open-Coastal Wetland Sites, Central Cascadia Margin“. PDXScholar, 2000. https://pdxscholar.library.pdx.edu/open_access_etds/3361.
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Mapping and stratigraphic investigations of back barrier, open-coastal plain sites have been used to establish minimum inundation distances and wave heights of tsunami produced by great subduction zone earthquakes in the central Cascadia margin. Cascadia tsunami deposits have been reported for many coseismic subsidence events in bay marsh settings where tidal-channel features focus tsunami energy. Variable magnitude (8.5±0.5 Mw), frequency (500±300 yr recurrence), and rupture geometry produce widely varying computer model outcomes for Casdcadia tsunami inundation. The results presented in this thesis provide specific quantitative data regarding tsunami inundation at the open coast.
Anomalous sand sheets that have been characterized consist of well-sorted beach sand that fine up-section. The thickness of the deposits vary from 45 em to 0.2 em, and thin in the landward direction. Many of the sand layers include detrital caps. One to three detritus and mud lamina are intra-layered in the deposits. Marine diatoms and bromine, a marine tracer, increase in concentration at each of the sand layers.
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Dewey, Felicity Joy. „The sedimentology and palaeoenvironmental significance of vlei sediments on the Winterberg range, South Africa“. Thesis, Rhodes University, 1989. http://hdl.handle.net/10962/d1001897.
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Palaeoenvironmental reconstruction of the late Pleistocene and Holocene geological periods for central and southern Africa has been hampered by the erratic distribution of suitable sites, incomplete and inaccurately dated sequences and the limited nature of published data. One geomorphological feature which has supplied valuable evidence for fluctuations in past environmental conditions, is the vlei or dambo. The type-site of these waterlogged features is in south central Africa, but similar features have been described on other continents. The clastic and organic sediments contained within these features are affected by, and therefore reflect to some degree, the environment under which they were formed. The characteristics of the sediments supply information as to their transport and mechanisms of deposition. From these processes, the environmental conditions at the time of vlei formation can be inferred. The environmental history of the Eastern Cape region has been considerably neglected, and is far less well understood than other countries such as Malawi, Zambia and Zimbabwe. A study site in the Winterberg Range (Eastern Cape) was selected which permitted the comparison of two vleis, the objective being to establish an accurate late Pleistocene sediment chronology for the entire plateau area. Radiocarbon dates from organic layers indicate that these sediments span the last 12 000 years BP, suggesting that organic accumulation at this site began at roughly the same time as at sites further afield. The vlei sediments are analysed in terms of their morphology, particle slze distribution, and other physical and chemical characteristics. These data facilitate the construction of detailed stratigraphic diagrams and a chronological summary of sediment accumulation, from which the period and governing processes of vlei development under changing environments may be described. It is found that the Winterberg vleis contain sediments which respond to changes in the prevailing environment. This makes these sediments useful indices from which to trace such changes during the late Pleistocene and Holocene times. These features are found to be similar in many respects to those described elsewhere in Southern Africa. The study attempts to provide greater understanding of contemporary vlei processes and emphasises the necessity of their preservation, as finite and valuable resources, by future generations
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Adomat, Friederike [Verfasser], Eberhard [Akademischer Betreuer] Gischler und Wolfgang [Akademischer Betreuer] Oschmann. „Holocene evolution of coastal lagoon environments in Belize, Central America : analysis of stratigraphic patterns, mollusk shell concentrations and storm deposition / Friederike Adomat. Gutachter: Eberhard Gischler ; Wolfgang Oschmann“. Frankfurt am Main : Universitätsbibliothek Johann Christian Senckenberg, 2016. http://d-nb.info/1098308182/34.
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Dittmers, Klaus Hauke. „Late Weichselian to Holocene sedimentation in the inner Kara Sea : qualification and quantification of processes = Sedimentationsprozesse in der inneren Kara-See (Spät-Weichsel bis Holozän) /“. Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 2006. http://www.gbv.de/dms/goettingen/510037178.pdf.
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Crowe, Douglas E. „Stratigraphy and geologic history, Bunces Key, Pinellas County, Florida / by Douglas E. Crowe“. University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000022.
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Title from PDF of title page.Document formatted into pages; contains 113 pages.
Thesis (M.S.)--University of South Florida, 1983.
Includes bibliographical references.
Text (Electronic thesis) in PDF format.
ABSTRACT: Bunces Key, a narrow, linear, barrier island on the west-central coast of Florida, was formed in 1961. Its growth and development since that time is well documented by aerial photography. Cores taken from the Key and surrounding areas reveal a stratigraphic succession of facies reflecting rapid vertical aggradation. Sedimentation began on a gently sloping platform through the landward migration of large scale bedforms (sand waves) during fair weather periods. Migration of these bedforms ceased when emergence and lack of continued overwash precluded further movement.
Vertical accretion to supratidal levels resulted from the continued onshore transport of sediment and subsequent welding to the previously formed bars. Stratigraphically, the barrier exhibits a "layer-cake" type of stratigraphy, with nearshore sediments overlain by foreshore, backbeach, and dune deposits. The backbarrier generally exhibits muddy lagoon sediments intercalated with washover and channel margin sediments.Fining upward washover sequences reflect the unstable nature of the island.
Low pressure systems commonly cause overtopping of the barrier, with the subsequent formation of tidal inlets and washover fans. Aerial photographs document the formation of an initial barrier that was breached twice prior to 1973. A second barrier formed in late 1973 just seaward of the initial island and subsequently grew through littoral drift to a length of 1.8 km. A narrow inlet (30 m) formed through the northern end of the island in 1982.
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Mode of access: World Wide Web.
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Stoneman, Rob. „Holocene palaeoclimates from peat stratigraphy : extending and refining the model“. Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317945.
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Langdon, Peter G. „Reconstructing Holocene climate change in Scotland utilising peat stratigraphy and tephrochronology“. Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310073.
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Macphail, Gillian Mary. „Pollen stratigraphy of Holocene peat sites in eastern Liguria, northern Italy“. Thesis, London Metropolitan University, 1988. http://repository.londonmet.ac.uk/3033/.
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This thesis presents the results of a research project designed to reconstruct the Holocene vegetation history of eastern Liguria. The study area lies within the northern Apennines, a region from which few detailed late Quaternary palaeoenvironmental records had boon published and prior to this study no radiocarbon-dated pollen profiles had been reported. Presented hare are the results of pollen-stratigraphical investigations (including pollen concentration and pollen preservation data) from six Holocene peat sites, augmented by twelve radiocarbon dates. The data provide a first regional assessment of the mid- and late Holocene vegetation succession in Liguria as well as a detailed examination of the problems of sampling and interpretation encountered. The sites are situated at a range of altitudes between 831 m to 1481 m and consist of both infilled basins within drift deposits as well as shallow shelf sites. However most of the peat sequences began to form only 4000 to 5000 years ago. At three sites there are strong indications that peat formation only occurred after major disruption of local soils which locally may have been initiated by human (Chalcolithic) forest disturbances. Nevertheless there is also a lack of known early Holocene peat or lake sediments in much of northwestern Italy suggesting widespread climatic conditions inimical to peat development during that period. The biostratigraphical data indicate that Abies forests were common at altitudes of over 1000 a during the mid-Holocene but these declined from approximately 2000 BP and subsequently, woodlands were dominated by Fagus. Certain types suggest that these changes in forest composition could have been related to human activity, although forest clearance appears to have been restricted. The evidence overall suggests that there was major disruption of local soils during the mid- and late Holocene and it is suggested, therefore, that changes in soil moisture regimes possibly as a result of human disturbance, may have led to permanent changes in the vegetation cover.
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Wheeler, Andrew James. „Stratigraphy and palaeoenvironments of Late Holocene sediments in north-central Fenland, U.K“. Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319867.
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Gonthier, Nicole. „Holocene stratigraphy and sedimentation off the Great Whale River entrance, southeastern Hudson Bay“. Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61215.
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The regional distribution of Holocene sediments of eastern Hudson Bay off the Great Whale River mouth was mapped using a grid of reflection seismic lines over 60 km long and covering an area of approximately 800 km$ sp2$ and data from eight piston cores. A larger data base and a greater area of study than that used in previous studies significantly increases our understanding of the sedimentation and deglaciation processes that have occurred in the area since the last deglaciation. Based on the seismic records and piston cores, four stratigraphic units overlying the Proterozoic bedrock (unit 1) were defined and interpreted: unit 2, glacial till deposited by a westward flowing ice sheet; unit 3, glaciolacustrine stratified muds deposited in glacial Lake Ojibway; unit 4, postglacial marine muds deposited in Tyrell Sea; unit 5, distal fluvio-deltaic sediments from the Great Whale River. Textural and geochemical analyses of individual laminae suggest that unit 3 rhythmites are true varves; dark "summer" laminae were deposited mainly by underflows during the open water season, and light "winter" laminae were deposited by overflows-interflows under a seasonal ice cover. Unit 5 covers approximately 400 km$ sp2$ and occurs as a deltaic constructional wedge which reaches 11 km offshore of the Great Whale River entrance. It was deposited between 3500 BP and 2800 BP from material supplied by the erosion of the Sakami Moraine and of glaciolacustrine and marine muds exposed along the river banks.
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Summa, Michelle Carlene. „Geologic Mapping, Alluvial Stratigraphy, and Optically Stimulated Luminescence Dating of the Kanab Creek Area, Southern Utah“. DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/506.
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At the turn of the century, Kanab Creek incised 30-meters into its alluvium, leaving behind fluvial terraces and thick basin fill sediments exposed along arroyo walls. Research objectives were to determine the timing and causes of past valley-filling and arroyo-cutting episodes along a 20 km-long reach of Kanab Creek in southern Utah. Fluvial deposits were mapped at the 1:12,000 scale and sediments were described and dated using Optically Stimulated Luminescence (OSL) and radiocarbon dating. The Kanab Creek valley can be divided into a narrow, upper terraced reach and a broad lower basin fill reach near Kanab, Utah. The most prominent terrace in the upper reach is Quaternary alluvial terrace 4 (Qat4), followed by Qat3, Qat2/3, and Qat2 map units. These are composed of tabular-bedded, fine-grained sand, silt, and clay layers. The Qat2/3 map unit is a both a fill and fill-cut terrace underlain by Qa4, Qa3, and Qa2 alluvium and is used when the Qat3 fill-cut (fill-strath) terrace can not be differentiated from the Qat2 fill terrace due to their similar geomorphic position. The Qat3 fill-cut terrace upstream correlates to ~8 meters of aggradation downstream. The youngest terrace, Qat1, is a minor terrace, composed of coarse-grained channel facies. More recent channel and floodplain deposits were deposited over the last century following arroyo cutting. OSL and radiocarbon results suggest at least four cycles of fluvial cutting and filling: >6-3.5ka (Qa4), ~3->1ka (Qa3), 0.7-0.12ka (Qa2), and post-1880 AD (Qa1). Correlation to regional climate records suggests major periods of aggradation correlate to regionally cooler and wetter climatic intervals. Periods of arroyo cutting occurred at >6ka, ~3ka, 1-0.7ka, and during historic arroyo cutting (1882-1914 AD), and correlate to regionally warmer, drier intervals. These periods of aggradation and incision are roughly contemporaneous with regional drainages, except for the large aggradation seen in Kanab Creek 6-3.5ka (Qa4). Analysis of terrace longitudinal profiles indicates Qat4 has the lowest concavity suggesting that Qat4 aggraded during a period of greater sediment supply and/or reduced flood regime. Although OSL samples exhibited some degree of incomplete zeroing, calculated ages using a minimum age model are consistent with radiocarbon results.
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Meyer, Brian K. „Shoreline Dynamics and Environmental Change Under the Modern Marine Transgression: St. Catherines Island, Georgia“. Digital Archive @ GSU, 2013. http://digitalarchive.gsu.edu/geosciences_diss/5.
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The current study has evaluated shoreline dynamics and environmental change at St. Catherines Island, Georgia, with attention to the two major controls of barrier island formation and modification processes. These major controls include the increase in accommodation space, or the rate of sea level rise for the Georgia Bight which has remained constant in 20th and 21st century tide gauge data and dynamically changing rates of sediment supply based on anthropogenic modifications to land cover (Trimble, 1974) that are reflected in sediment transport (McCarney-Castle et al., 2010). Vibracoring and radiocarbon data provided valuable insights into the stratigraphy and development of St. Catherines Island. A stratigraphic model has been developed for the sediments associated with the Late Holocene accretional terrains where multiple small scale fluctuations in sea level have resulted in the formation of a sedimentary veneer punctuated with transgressive surfaces and regressive sequences. A working model for an interpolated Late Holocene sea level curve has been constructed using direct evidence from vibracore data as constraining points and indirect evidence from other regional sea level studies to provide additional structure. The relationship between the timing of the regressions versus periods of beach ridge formation and implications from the current shoreline dynamics study regarding the role of sediment supply complement each other. The ages of beach ridge formation strongly correlate to periods that are associated with regressions in sea level based on the sedimentary record and an evaluation of Late Holocene sea level conditions. The evaluation of anthropogenic modifications to the rate of sediment supply performed under the current study indicates that in spite of significant changes in sediment flux rates of +300% (pre-dam era) and -20% (post-dam era), shoreline retreat was continuous during the study period with an acceleration noted in the rates of shoreline retreat associated with spit and berm landforms during the post-dam or modern era. The two associations indicate strongly that the rate of sediment supply plays a secondary role to the major control of the rate of sea level rise in the formation and modification processes at St. Catherines Island.
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Loso, Michael Gregg. „Late holocene climate and glacier response reconstructed using stratigraphy and lichenometry at Iceberg Lake, Alaska /“. Diss., Digital Dissertations Database. Restricted to UC campuses, 2004. http://uclibs.org/PID/11984.
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Levesh, Jarrett Leigh. „Middle Miocene to Holocene History of the Delacroix Island Fault System“. ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/td/2623.
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An in-depth field study of the Delacroix Island producing field illustrates the evolution of the east-trending Delacroix Island Fault during the last 13 My. Well log correlations and 3-D seismic interpretation of 22 subsurface bio-stratigraphic horizons across the fault reveal variable stratigraphic thicknesses and displacement. Wells, with well log curve data as shallow as 31 m (100 ft) below the surface, were used to calculate interval thicknesses, expansion indices, sediment accumulation rates, burial history and magnitudes of displacement. Through these analyses, a correlation was found between the positioning of ancient Miocene depocenters over Delacroix Island and a period of increased fault activity. Historic satellite imagery (last 34 yrs) of the field depicts a lineation on the modern marsh surface coincident with the upward projected fault plane. Continuous wetland loss on the downthrown side of the fault trace suggests that recent and continued fault movement may be contributing to marsh submergence.
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Ivarsson, Lena. „Holocene environmental changes as recorded in sediments from Kaggfjärden, southern archipelago of Stockholm, using diatom stratigraphy“. Thesis, Södertörns högskola, Institutionen för livsvetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-7494.
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Four sediment cores were sampled in Kaggfjärden, located in the southern archipelago of Stockholm. Two of the cores were analyzed with respect to the diatom record and lithology. Terrestrial macrofossils were dated using Carbon-14 dating. The aim of the study was to detect and date changes in the environment of Kaggfjärden by using the diatom stratigraphical record. These environmental changes were then interpreted in terms of climate change and/or anthropogenic impact. The results show that the lowermost part of the core was deposited approximately 6300 cal yr BP, thus from the Littorina Sea, a warmer and more marine phase in the Baltic Sea history. The diatom record in these layers is dominated by the typical Littorina species, Pseudosolenia calcar-avis (Schultzee). Both the diatom record and the lithology show that e.g. erosion or non-deposition caused a hiatus in the sediment core; several thousands of years are missing. The following levels were deposited during the 15th century and indicate an environment with greater visibility and less distribution of hypoxia than today. This coincides with the so called “Little Ice Age”. The uppermost part of the core consists of laminated sediments, and by counting the laminations it is clear that the area has suffered from hypoxia for about 110 years. This is interpreted as a result of the big changes in the agricultural landscape that occurred around that time. Further up in the core a change in the diatom assemblage from being dominated by benthic taxa, to planktonic, indicates more turbid water and poor visibility. This is probably a result of the opening of the nearby sewage treatment plant, Himmerfjärdsverket, in the mid 1970´s. The upper layers indicate no improvement in the water quality, rather a more turbid and overloaded situation. This study could be a part of the process of determining what “good environmental status” in the Baltic Sea means, and therefore be at help when monitoring future environmental work in the area.
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Blundell, Antony Colin. „Late-Holocene multi-proxy climate records for northern Britain and Ireland derived from raised peat stratigraphy“. Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246376.
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Ouellon, Marie-Pierre. „Morphologie et stratigraphie des dépôts littoraux holocènes du détroit de Manitounuk, Québec nordique“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq25346.pdf.
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Griffiths, Ann Hilary. „A stratigraphical, sedimentological and palaeoenvironmental analysis of Holocene and present-day coastal sedimentation : Wigtown Bay, S.W. Scotland“. Thesis, University of Glasgow, 1988. http://theses.gla.ac.uk/1455/.
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Evidence of Holocene marine transgression and regression in South-West Scotland is exhibited in the stratigraphical record of present and former coastal deposits. Remnant areas of Holocene coastal (including marine) sediments are preserved at the head of marine inlets and estuaries along the northern shore of the Solway Firth and may extend up to 10km inland, indicating significant changes in coastal configuration as a result of marine transgression and regression during the last 10,000 years.At the head of Wigtown Bay, former Holocene coastal deposits are well exposed along the incised meanders of the upper Cree estuary and Palnure Burn. Referred to in the literature as `carse deposits', these sediments are products of several different environments.During late-Pleistocene times and very early in the Holocene Epoch, the upper Cree estuary area north of Creetown was a low lying boggy environment. The area was marginally marine in character. The exact position of the palaeo-Cree is uncertain but the river flowed in a general NW to SE direction and may have been braided. The marine waters of the Holocene marine transgression flooded northwards, penetrating the upper Cree estuary c . 7,900 years B.P., leading to the deposition of low to high tidal-flats. By 6,480107 years B.P. local regression had begun and seaward progradation of high upper tidal-flats and marsh had started. This environmental situation prevailed until 5,000 years B.P., when incision occurred and terrestrial conditions became dominant.In the lower Cree estuary, waters of the Holocene marine transgression initially flooded the lower courses of rivers and rose to flood the hollows in the uneven surface of the fluvio-glacial deposits flanking the estuary.Accumulation of low tidal-flat deposits gave way to upper tidal-flat and marsh deposits as the transgression diminished. The transgressive event was shortlived. Sediments were deposited at the `feather edge' of the transgression. North of Creetown and the Moneypool Burn, upper tidal-flat and marsh deposits rest directly on fluvio-glacial deposits. As regression occurred, seaward progradation and incision of the carse deposits proceeded.A pause in regression c . 2,000 years B.P. resulted in certain morphological features observed in the Cassencarie area. Stormy conditions resulted in the re-working of marginal fluvio-glacial deposits to form a spit, and to the south (between Cassencarie and Carsluith) coarse marine sands and gravels were transported landwards to form shore-parallel and oblique bars. At Carsluith, similarly-derived material forms a thinly-developed beach blanket. Recession of the sea has proceeded since 2,000 years B.P. to the present-day.
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Maike, Christopher A. „A Flood-Tidal Delta Complex, The Holocene/Pleistocene Boundary, and Seismic Stratigraphy in the Quaternary Section off the Southern Assateague Island Coast, Virginia, USA“. University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1408097363.
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