Um die anderen Arten von Veröffentlichungen zu diesem Thema anzuzeigen, folgen Sie diesem Link: Vincent Gulf Region Eocene.
Zeitschriftenartikel zum Thema „Vincent Gulf Region Eocene“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit Top-34 Zeitschriftenartikel für die Forschung zum Thema "Vincent Gulf Region Eocene" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Sehen Sie die Zeitschriftenartikel für verschiedene Spezialgebieten durch und erstellen Sie Ihre Bibliographie auf korrekte Weise.
1
Sontag, Elżbieta, und Ryszard Szadziewski. „Biting midges (Diptera: Ceratopogonidae) in Eocene Baltic amber from the Rovno region (Ukraine)“. Polish Journal of Entomology / Polskie Pismo Entomologiczne 80, Nr. 4 (01.12.2011): 779–800. http://dx.doi.org/10.2478/v10200-011-0058-4.
Der volle Inhalt der QuelleAnnotation:
Biting midges (Diptera: Ceratopogonidae) in Eocene Baltic amber from the Rovno region (Ukraine) The paper presents the results of an examination of 714 biting midges (Diptera: Ceratopogonidae) preserved in Baltic amber from the Rovno deposits in Ukraine. A new species - Leptoconops rovnensis sp. n. - is described and illustrated. 29 of the fossil species reported here have already been described from other deposits of Baltic amber: 26 of these were also found in amber from the Gulf of Gdańsk and 18 in amber from Bitterfeld (Saxony). The most common genera of biting midges in Ukrainian amber are also found in amber from Bitterfeld and the Gulf of Gdańsk, and with very much the same frequencies. The results indicate that the faunas of Ceratopogonidae enclosed in amber from Rovno, Bitterfeld and the Baltic are very similar, showing that they inhabited similar palaeoenvironments in the same palaeogeographic region.
2
Carreño, Ana Luisa, und Thomas M. Cronin. „Middle Eocene Ostracoda from Baja California Sur, Mexico“. Journal of Micropalaeontology 12, Nr. 2 (01.12.1993): 141–53. http://dx.doi.org/10.1144/jm.12.2.141.
Der volle Inhalt der QuelleAnnotation:
Abstract. One genus and six new species of ostracodes are described from the Bateque Formation on the Pacific Coast of Baja California Sur, Mexico. Planktonic foraminifers indicate a mid Eocene age and the whole assemblage is characteristic of a shallow warm-water environment. Paijenborchella mezquitalensis sp. nov. is the second record of the genus Paijenborchella from the Eocene of North America. Except for this species and the new genus Bajacythere, the ostracode association has strong affinities with those described from the lower Tertiary Gulf Coast region.
3
Uhen, Mark D., und David Taylor. „A basilosaurid archaeocete (Cetacea, Pelagiceti) from the Late Eocene of Oregon, USA“. PeerJ 8 (02.10.2020): e9809. http://dx.doi.org/10.7717/peerj.9809.
Der volle Inhalt der QuelleAnnotation:
Background Basilosaurid archaeocetes are known from the Late Eocene of virtually all coastlines bearing coeval marine rocks except the North Pacific Basin, until now. Here we report on three consecutive posterior thoracic vertebrae of a large, basilosaurid archaeocete from a Late Eocene horizon in the Keasey Formation in Oregon. Methods These vertebrae were morphologically and morphometrically compared to other vertebrae of similar age from around the world. Results The specimens were determined to be different from all currently named species of fossil cetacean, but most similar to those found in the Gulf Coast region of North America. These vertebrae represent the first confirmed specimen of a Late Eocene basilosaurid from the North Pacific. These and other basilosaurids known only from vertebrae are reviewed here in the context of Late Eocene paleoceanography and cetacean evolution.
4
Jiang, Mark M. „Middle Eocene through basal Miocene sequence bio-stratigraphy of the western Gulf Coast region“. Marine and Petroleum Geology 14, Nr. 7-8 (November 1997): 855–66. http://dx.doi.org/10.1016/s0264-8172(97)00049-4.
Der volle Inhalt der Quelle
5
Scheibner, C., A. M. Marzouk und J. Kuss. „Maastrichtian-Early Eocene litho-biostratigraphy and palægeography of the northern Gulf of Suez region, Egypt“. Journal of African Earth Sciences 32, Nr. 2 (Februar 2001): 223–55. http://dx.doi.org/10.1016/s0899-5362(01)90005-3.
Der volle Inhalt der Quelle
6
Golubovskaya, E. V. „Specific features of the geochemistry of Eocene-Miocene rocks in the Perovskii Gulf, northern Aral region“. Lithology and Mineral Resources 42, Nr. 3 (Mai 2007): 281–88. http://dx.doi.org/10.1134/s0024490207030078.
Der volle Inhalt der Quelle
7
Lin, Yani, Tianze Zhang und Kelly H. Liu. „Turbidite lobe deposits in a canyon-fill system“. Interpretation 9, Nr. 2 (07.04.2021): C17—C21. http://dx.doi.org/10.1190/int-2020-0111.1.
Der volle Inhalt der QuelleAnnotation:
Geological feature: Turbidite lobe deposits in a canyon-fill system Seismic appearance: Isolated and irregularly shaped sandstone pods Alternative interpretations: Mid-channel bars in a braided channel system Features with similar appearance: Alluvial fans Formation: Lower Wilcox Group Age: Late Paleocene to Early Eocene Location: Shelf edge at the Central Gulf Coast Region of Texas Seismic data: Donated by a petroleum exploration company in Houston, Texas Analysis tools: Seismic attributes such as instantaneous phase, root-mean-square amplitude, and spectral decomposition
8
Tucker, Annette B., und Rodney M. Feldmann. „Fossil decapod crustaceans from the lower Tertiary of the Prince William Sound Region, Gulf of Alaska“. Journal of Paleontology 64, Nr. 3 (Mai 1990): 409–27. http://dx.doi.org/10.1017/s0022336000018643.
Der volle Inhalt der QuelleAnnotation:
Sixty-five fossil brachyuran crabs, collected from rocks of the Orca Group, Tokun Formation, and Poul Creek Formation, have been assigned to six species, five of which were described previously. One of these, Pilumnoplax hannibalanus, is reassigned to Neopilumnoplax. Morphologic descriptions of Raninoides vaderensis, Eumorphocorystes naselensis, Portunites alaskensis, and Branchioplax washingtoniana are emended. Orbitoplax plafkeri n. gen. and sp. is described from the Poul Creek Formation on Wingham Island. The diagnosis of age for the Orca Group has been problematic. However, the well-preserved brachyurans, Branchioplax washingtoniana, Neopilumnoplax hannibalanus, and Raninoides vaderensis, provide corroborative evidence for an Eocene or older age for the rocks. Alaskan decapods include species common to the entire Pacific coast north of California, as well as species endemic to Alaska.
9
Carter, B. D., T. H. Beisel, W. B. Branch und C. M. Mashburn. „Substrate preferences of Late Eocene (Priabonian/Jacksonian) echinoids of the eastern Gulf Coast“. Journal of Paleontology 63, Nr. 4 (Juli 1989): 495–503. http://dx.doi.org/10.1017/s0022336000019715.
Der volle Inhalt der QuelleAnnotation:
Thin sections and acetate peels of the sediment within, and adhering to the outsides of, tests of Late Eocene echinoids from the southeastern United States have proven to be useful checks on inferences from test morphology concerning substrate preference. Previous characterizations of species' sediment preferences have concentrated primarily on the functional morphology of spatangoids, and relied particularly heavily upon Recent relatives of nonspatangoids. Reassessment of the preferences of spatangoids has led to a few discrepancies between interpretations herein and those of previous workers. In addition, this study attempts a more thorough assessment of functional morphology of nonspatangoid irregular echinoids than has previously been tried.Carbonate sand-dwelling species from the Ocala Limestone (thin sections are clean grainstones) include Oligopygus, Echinolampas, Rhyncholampas, fibulariids, Durhamella, Neolaganum, Agassizia, Macropneustes, some species of Plagiobrissus and Periarchus, and most species of Eupatagus. All these have been interpreted previously as preferring clean sand. Species that preferred, or at least tolerated, significant carbonate mud in the substrate (thin sections are poorly washed grainstones and packstones) include all the regular echinoids and the irregular echinoids Schizaster, Ditremaster, Brissopsis, Brissopatagus, Amblypygus, Eurhodia, Weisbordella, Wythella, Paraster, some species of Periarchus and Plagiobrissus, and perhaps some species of Eupatagus. The last seven of these have previously been interpreted as sand-dwellers.In general, species preferring mud-rich sands are found in the upper Ocala of peninsular Florida and in the middle to upper Ocala equivalents in the rest of the Gulf Coast. Sand-dwellers are most often found in the lower Ocala strata of both regions and up into the middle Ocala in Florida. These generalizations are consistent with existing paleoenvironmental models for the region.
10
Cotton, Laura J., Wolfgang Eder und James Floyd. „Larger foraminifera of the Devil's Den and Blue Hole sinkholes, Florida“. Journal of Micropalaeontology 37, Nr. 1 (23.03.2018): 347–56. http://dx.doi.org/10.5194/jm-37-347-2018.
Der volle Inhalt der QuelleAnnotation:
Abstract. Shallow-water carbonate deposits are well-known from the Eocene of the US Gulf Coast and Caribbean. These deposits frequently contain abundant larger benthic foraminifera (LBF). However, whilst integrated stratigraphic studies have helped to refine the timing of LBF overturning events within the Tethys and Indo-Pacific regions with respect to global bio- and chemo-stratigraphic records, little recent work has been carried out in the Americas. The American LBF assemblages are distinctly different from those of Europe and the Indo-Pacific. It is therefore essential that the American bio-province is included in studies of LBF evolution, biodiversity and climate events to understand these processes on a global scale. Here we present the LBF ranges from two previously unpublished sections spanning 35 and 29 m of the upper Eocene Ocala limestone, as the early stages of a larger project addressing the taxonomy and biostratigraphy of the LBF of Florida. The study indicates that the lower member of the Ocala limestone may be Bartonian rather than Priabonian in age, with implications for the biostratigraphy of the region. In addition, the study highlights the need for multiple sites to assess the LBF assemblages and fully constrain ranges across Florida and the US Gulf and suggests potential LBF events for future integrated stratigraphic study.
11
Carter, Burchard D., und Michael L. McKinney. „Eocene echinoids, the Suwannee Strait, and biogeographic taphonomy“. Paleobiology 18, Nr. 3 (1992): 299–325. http://dx.doi.org/10.1017/s0094837300010861.
Der volle Inhalt der QuelleAnnotation:
Faunal similarity among regions is often used as a means of identifying regions of endemism in fossil faunas. At least two large-scale taphonomic effects can affect apparent faunal similarity: stratigraphic and facies mismatching. In stratigraphic mismatching, an unconformity represents removal of most or all of a complete assemblage zone in one region, and the constituent taxa are mistakenly interpreted as having never inhabited that region. In facies mismatching, environmental differences between two regions (possibly unrecognized) cause the inference of a barrier that never existed. The two types of mismatching can work in concert if a facies was originally represented in a single stratigraphic interval that has been completely removed from one region. Analysis of faunal similarity via multivariate analysis of individual localities, coupled with comparison of the regions as single samples, may indicate mismatching if the results differ significantly.We view these two problems as part of a suite of taphonomic effects that are not evident in paleobiological analyses of smaller geographic scope. First, there is ambiguity in the notion of “barrier,” even when a candidate is obvious. Second, barriers in paleobiogeography are often hidden and must be inferred from their effects rather than observed. Third, stratigraphic and facies mismatching produce effects on regional faunas similar to those produced by barriers. Anyone using barriers to explain faunal disruptions should address these three points.Upper Eocene faunas of central Florida seem taxonomically distinct from those of the remainder of the Gulf Coastal Plain. This has historically been attributed to a known paleogeographic feature, the Suwannee Strait, which acts as a barrier. The amount of dissimilarity of the echinoid faunas is greater than the amount predicted as a result of sampling problems. Comparison of the results of multivariate and whole-region analyses suggests that mismatching of the two faunas, rather than a true barrier, causes the distinction. Principally facies, but also strata are mismatched. Early Late Eocene faunas inhabited terrigenous sands to the north of the strait and carbonate sands to the south and show the highest distinctiveness. Middle Late Eocene faunas inhabited primarily carbonate sands to the south and both carbonate sands and muds to the north. Overall similarity is higher for both local and regional analyses, and the faunas of northern sands are more similar to those of the southern region than to the northern mud faunas. Overall similarity across the strait is highest in the late Late Eocene strata when both regions had carbonate mud and sand facies. The faunas exhibit greater similarity within facies than they do within regions. Upper Late Eocene strata are poorly preserved north of the strait because of post-Eocene erosion.
12
Tomo, Ikuko, und Catherine M. Kemper. „Strandings in St Vincent Gulf Bioregion, South Australia: 12-Year Study Monitors Biology and Pathology of Cetaceans“. Oceans 3, Nr. 4 (26.09.2022): 439–63. http://dx.doi.org/10.3390/oceans3040030.
Der volle Inhalt der QuelleAnnotation:
The semi-enclosed environment of the St Vincent Gulf Bioregion and its fauna are impacted by many human activities. Long-term monitoring of cetaceans is vital. Records of collected specimens (173) and those not examined by the South Australian Museum (98 non-specimens) from 2009–2020 were analyzed. Necropsies were carried out on most carcasses using gross, histopathological, and diagnostic assessment of pathogens, organs, and skin lesions. The relative age and circumstance of death were assigned. Baleen whales (five species) and odontocetes (eight species) were studied. Indo-Pacific bottlenose dolphins (Tursiops aduncus) and common dolphins (Delphinus delphis) were frequently recorded and analyzed in detail. Anthropogenic cases were prevalent (21%). Many dolphins (62%) were immature males. Disease (73%) was the most frequently recorded circumstance of death. The most common pathological change was inflammatory disease, including infectious pneumonia. In Indo-Pacific bottlenose dolphins, infectious disease was more prevalent in the greater St Vincent Gulf Bioregion than in the Adelaide Dolphin Sanctuary. Microbe testing confirmed 32 species of bacteria, 2 fungi, and 1 virus. Nematodes and trematodes were recorded throughout the study, sometimes in association with microbes. Toxoplasma gondii was observed in an Indo-Pacific bottlenose dolphin. Severe traumatic injury was recorded in many dolphins, including anthropogenic cases. A tumor (leiomyoma) was described from a single common dolphin. This study provides an important baseline for the future monitoring of emerging infectious and chronic diseases, and anthropogenic threats in the region.
13
Jablonski, D., S. Pono und O. A. Larsen. „PROSPECTIVITY OF THE DEEPWATER GULF OF PAPUA AND SURROUNDS IN PAPUA NEW GUINEA (PNG)—A NEW LOOK AT A FRONTIER REGION“. APPEA Journal 46, Nr. 1 (2006): 179. http://dx.doi.org/10.1071/aj05011.
Der volle Inhalt der QuelleAnnotation:
Despite limited well control and paucity of seismic data, a regional study of the deepwater portion of the Gulf of Papua, Papua New Guinea (PNG), indicates a number of large structures at a variety of stratigraphic levels that are capable of holding significant volumes of hydrocarbons. The main structural elements east of the Fly River Platform the Pandora Ridge, Pandora Trough, Aure Trough, Port Moresby Trough and the northern portion of the Eastern Plateau were established during the Paleozoic and further enhanced by Late Cretaceous to Early Paleocene Coral Sea rifting in the southeast. Structuring in the region is mostly basement involved and extensional, and is overprinted by a later compressional pulse. Extensional and compressional regimes produce many potential traps. To date, exploration in the Gulf of Papua has been sporadic and mainly focussed in shallow water depths. The new reprocessed seismic data indicate the following Paleozoic to Recent plays, some of which contain multiple reservoir-seal pairs, sourced by non-marine and marine source rocks:extensional Paleozoic rift fault blocks;Upper Jurassic to Lower Cretaceous turbidites (Iagifu- Hedina-Toro sandstone equivalents);Campanian to Middle Paleocene Coral Sea synrift sandstone and basin floor fan equivalents (Pale/Barune Formations and equivalents);Middle Paleocene break-up unconformity fault blocks and intra-basinal highs;Upper Paleocene to Lower Eocene Pima Sandstone equivalent associated with the Middle Paleocene uplift and erosion;Oligocene to Lower Miocene lowstand deltas and turbidites;Miocene to Recent biohermal build-ups (possibly including a new limestone high, the Box Ridge, in front of the Pandora Ridge); Karstified Darai Limestone equivalent sealed by Aure Beds claystones;Miocene to Recent lowstand deltas and turbidites;Eocene to Pliocene stratigraphic onlaps flanking main structural highs; and,compressional plays associated with the Pliocene to Recent collision of the PNG and Pacific plates.
14
Jackson, William T., Matthew P. McKay, Donald A. Beebe, Carolyn Mullins, Adelie Ionescu, Barry Shaulis und David L. Barbeau. „Late Cretaceous sediment provenance in the eastern Gulf Coastal Plain (U.S.A.) based on detrital-zircon U-Pb ages and Th/U values“. Journal of Sedimentary Research 91, Nr. 10 (08.10.2021): 1025–39. http://dx.doi.org/10.2110/jsr.2020.177.
Der volle Inhalt der QuelleAnnotation:
ABSTRACT Detrital-zircon U-Pb geochronology documents a regional- to continental-scale drainage reorganization along the eastern Gulf Coastal Plain (USA) from the Late Cretaceous (Cenomanian) to the Paleocene–Eocene. We present detrital-zircon U-Pb ages and Th/U values from the Maastrichtian Ripley Formation to determine the sedimentary provenance and to provide spatiotemporal resolution of drainage reorganization. The Ripley Formation contains a 12.7% overall average abundance of detrital zircons with low (< 0.1) Th/U values relative to the underlying Cenomanian Tuscaloosa Group (3.6%), the overlying Paleocene–Eocene Wilcox Group (2.8%), an Appalachian foreland composite (2.1%), and the laterally equivalent McNairy Sandstone in the northern Mississippi Embayment (3.8%). Multidimensional scaling of detrital-zircon U-Pb spectra shows that the Ripley Formation is dissimilar from underlying and overlying Gulf Coastal Plain units, the McNairy Sandstone, and an Appalachian foreland composite sample because of differences in proportions of Appalachian (490–270 Ma) and Grenville (1250–900 Ma) zircons. We interpret the southern Appalachian Piedmont province as the principal sediment source region for the Ripley Formation to account for the elevated abundance of grains with low (< 0.1) Th/U values and unique detrital-zircon U-Pb age spectra. Results suggest a regional-scale (105 km2) drainage network, which delivered sediment to the Maastrichtian coast followed by northwestward littoral transport and eventual mixing with Appalachian foreland-derived sediment in the northern Mississippi Embayment. This study further brackets drainage reorganization along the eastern Gulf Coastal Plain and demonstrates how simple chemical–age relationships, such as zircon Th/U values coupled with U-Pb ages, can be used to evaluate sediment provenance.
15
Van Vliet-Lanoë, Brigitte, Jean-Louis Mansy, Jean-Pierre Henriet, Michel Laurent und Jean-Pierre Vidier. „A tectonic inversion by steps during the Cenozoic : the Dover Strait“. Bulletin de la Société Géologique de France 175, Nr. 2 (01.03.2004): 175–95. http://dx.doi.org/10.2113/175.2.175.
Der volle Inhalt der QuelleAnnotation:
Abstract The Boulonnais is a dome incised by a former marine gulf inset into a zone of tectonic inversion from the Middle Eocene, which was already partly excavated at least at the Upper Eocene. New sedimentological and paleopedological data obtained within the Boulonnais, completed with old seismic profiles, allow a better understanding of the inversion process which developed step by step. The initial breaching probably took place in the late Eocene. The Dover Strait was probably opened during the Lutetian, a part of the Oligocene and the late Neogene. Oligocene and Pliocene faunal assemblages are identical on both sides of the Strait. It was closed again for tectonic and eustatic reasons in the early Quaternary and reopen subsequently just before the Last Interglacial. The opening is related to the evolution of the Western Channel and of its paleovalley system. The inversion of the Variscan front accommodates most of the shortening induced by the Pyrenean Orogen on the western border of the European plate. The inversion of the Dover Strait region is almost synchronous with those of other basins of the Channel and North Sea areas. Tectonic, geomorphologic and climatic implications of this dynamic are discussed within the western European context.
16
Smith, Kathlyn M., Alexander K. Hastings, Ryan M. Bebej und Mark D. Uhen. „Biogeographic, stratigraphic, and environmental distribution of Basilosaurus (Mammalia, Cetacea) in North America with a review of the late Eocene shoreline in the southeastern coastal plain“. Journal of Paleontology 96, Nr. 2 (29.10.2021): 439–51. http://dx.doi.org/10.1017/jpa.2021.90.
Der volle Inhalt der QuelleAnnotation:
AbstractA new specimen of Basilosaurus cetoides was discovered on the banks of the Flint River in Albany, Georgia, USA, in 2010. This fossil, which was the most complete specimen of the species from Georgia to date, consisted of five nearly complete and two partial post-thoracic vertebrae, tentatively identified as S4 through Ca6. During excavation, however, the site was looted and most of the specimen was lost to science. Nonetheless, we use this discovery as an opportunity to update the current state of knowledge on the stratigraphic, biogeographic, and environmental distribution of Basilosaurus in North America, as well as the position of the late Eocene shoreline in the southeastern United States. The results show that Basilosaurus was most abundant across the southeastern coastal plain during the early to middle Priabonian, coincident with the late Eocene maximum marine transgression. The decline in Basilosaurus localities is associated with the retreating shoreline of the terminal Eocene. The majority of Basilosaurus localities fall well south of the position of the late Eocene shoreline hypothesized in this study, suggesting the genus favored middle to outer neritic zones of the epicontinental sea. The comparatively low number of Priabonian specimens in the Atlantic Coastal Plain versus the Gulf Coastal Plain, then, suggests the presence of shallow zones in the Atlantic Coastal Plain that may have limited the distribution of Basilosaurus across the region. The hypothesized shoreline of this study ultimately differs from earlier reconstructions by extending the Mississippi embayment at the Bartonian/Priabonian boundary farther north than previously noted.
17
Frieling, Joost, Emiel P. Huurdeman, Charlotte C. M. Rem, Timme H. Donders, Jörg Pross, Steven M. Bohaty, Guy R. Holdgate, Stephen J. Gallagher, Brian McGowran und Peter K. Bijl. „Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia“. Journal of Micropalaeontology 37, Nr. 1 (13.02.2018): 317–39. http://dx.doi.org/10.5194/jm-37-317-2018.
Der volle Inhalt der QuelleAnnotation:
Abstract. Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large discrepancy between temperature proxy data and climate models in this region, suggesting a crucial error in model, proxy data or both. To resolve the origin of this discrepancy, detailed reconstructions are needed from both sides of the Tasmanian Gateway. Paleocene–Eocene sedimentary archives from the west of the Tasmanian Gateway have unfortunately remained scarce (only IODP Site U1356), and no well-dated successions are available for the northern sector of the AAG. Here we present new stratigraphic data for upper Paleocene and lower Eocene strata from the Otway Basin, southeast Australia, on the (north)west side of the Tasmanian Gateway. We analyzed sediments recovered from exploration drilling (Latrobe-1 drill core) and outcrop sampling (Point Margaret) and performed high-resolution carbon isotope geochemistry of bulk organic matter and dinoflagellate cyst (dinocyst) and pollen biostratigraphy on sediments from the regional lithostratigraphic units, including the Pebble Point Formation, Pember Mudstone and Dilwyn Formation. Pollen and dinocyst assemblages are assigned to previously established Australian pollen and dinocyst zonations and tied to available zonations for the SW Pacific. Based on our dinocyst stratigraphy and previously published planktic foraminifer biostratigraphy, the Pebble Point Formation at Point Margaret is dated to the latest Paleocene. The globally synchronous negative carbon isotope excursion that marks the Paleocene–Eocene boundary is identified within the top part of the Pember Mudstone in the Latrobe-1 borehole and at Point Margaret. However, the high abundances of the dinocyst Apectodinium prior to this negative carbon isotope excursion prohibit a direct correlation of this regional bio-event with the quasi-global Apectodinium acme at the Paleocene–Eocene Thermal Maximum (PETM; 56 Ma). Therefore, the first occurrence of the pollen species Spinizonocolpites prominatus and the dinocyst species Florentinia reichartii are here designated as regional markers for the PETM. In the Latrobe-1 drill core, dinocyst biostratigraphy further indicates that the early Eocene (∼ 56–51 Ma) sediments are truncated by a ∼ 10 Myr long hiatus overlain by middle Eocene (∼ 40 Ma) strata. These sedimentary archives from southeast Australia may prove key in resolving the model–data discrepancy in this region, and the new stratigraphic data presented here allow for detailed comparisons between paleoclimate records on both sides of the Tasmanian Gateway.
18
Holford, Simon, Richard Hillis, Ian Duddy, Paul Green, Martyn Stoker, Adrian Tuitt, Guillaume Backé, David Tassone und Justin MacDonald. „Cenozoic post-breakup compressional deformation and exhumation of the southern Australian margin“. APPEA Journal 51, Nr. 1 (2011): 613. http://dx.doi.org/10.1071/aj10044.
Der volle Inhalt der QuelleAnnotation:
We present results from a margin-wide analysis of the history of post-breakup Cenozoic compressional deformation and related exhumation along the passive southern margin of Australia, based on a regional synthesis of seismic, stratigraphic and thermochronological data. The Cenozoic sedimentary record of the southern margin contains regional unconformities of intra-Lutetian and late Miocene–Pliocene age, which coincide with reconfigurations of the boundaries of the Indo-Australian Plate. Seismic data show that post-breakup compressional deformation and sedimentary basin inversion—characterised by reactivation of syn-rift faults and folding of post-rift sediments—is pervasive from the Gulf St Vincent to Gippsland basins, and occurred almost continually since the early- to mid-Eocene. Inversion structures are absent from the Bight Basin, which we interpret to be the result of both the unsuitable orientation of faults for reactivation with respect to post-breakup stress fields, and the colder, stronger lithosphere that underlies that part of the margin. Compressional deformation along the southeastern margin has mainly been accommodated by reactivation of syn-rift faults, resulting in folds with varying ages and amplitudes in the post-rift Cenozoic succession. Many hydrocarbon fields in the Otway and Gippsland basins are located in these folds, the largest of which are often associated with substantial localised exhumation. Our results emphasise the importance of constraining the timing of Cenozoic compression and exhumation in defining hydrocarbon prospectivity of the southern margin.
19
Bryars, Simon R., und Mark Adams. „An allozyme study of the blue swimmer crab, Portunus pelagicus (Crustacea : Portunidae), in Australia: stock delineation in southern Australia and evidence for a cryptic species in northern waters“. Marine and Freshwater Research 50, Nr. 1 (1999): 15. http://dx.doi.org/10.1071/mf98075.
Der volle Inhalt der QuelleAnnotation:
Allozyme analysis was used to examine the species-level systematics and stock structure of the Australian blue swimmer crab Portunus pelagicus. Fifty-seven crabs from eight sites were screened in an overview study for allozyme variation at 35 loci. This overview study revealed the presence of two species, differing at a Nei D of 0.14 (2% fixed differences), in the Darwin region of northern Australia. One of these species corresponds to the common P. pelagicus found throughout Australia, whereas the other is most likely either an undescribed ‘cryptic’ species, or the east-Asian species P. trituberculatus. In total, 609 P. pelagicus from 11 sites covering three regions in South Australia and two regions in the Northern Territory were then genotyped at seven polymorphic loci and these data assessed, using goodness- of-fit and F-statistics, for the existence of subpopulations. Four discrete subpopulations could be discerned, namely West Coast, Spencer Gulf, and Gulf St Vincent in South Australia, and Darwin–Gove in the Northern Territory. No evidence of population substructuring among sites within each subpopulation was evident from the allozyme data. The results support the current recognition of the three South Australian regions as separate stocks, and suggest that a taxonomic revision of Indo-Pacific Portunus is warranted.
20
Cobiella-Reguera, Jorge L. „Emplacement of the northern ophiolites of Cuba and the Campanian-Eocene geological history of the northwestern Caribbean-SE Gulf of Mexico region“. Geological Society, London, Special Publications 328, Nr. 1 (2009): 315–38. http://dx.doi.org/10.1144/sp328.13.
Der volle Inhalt der Quelle
21
Bryars, Simon R. „Can regional nutrient status be used to predict plant biomass, canopy structure and epiphyte biomass in the temperate seagrass Amphibolis antarctica?“ Marine and Freshwater Research 60, Nr. 10 (2009): 1054. http://dx.doi.org/10.1071/mf08194.
Der volle Inhalt der QuelleAnnotation:
The seagrass Amphibolis antarctica is an important component of coastal soft-sediment ecosystems across southern Australia. Large-scale losses of A. antarctica at several locations have been linked to anthropogenic nutrient inputs. The present study comprised a field survey to test whether the spatial patterns of plant biomass, canopy structure and epiphyte biomass in A. antarctica could be predicted based on expectations related to nutrient status across two regions within Gulf St Vincent, South Australia. Specific predictions were that: (1) plant biomass, plant density, plant height, leaf cluster frequency and leaf frequency are all lower in the east (higher nutrient) region than in the west region; and (2) epiphyte biomass and epiphyte load are higher in the east than in the west. Regional nutrient status was a poor predictor of most of the parameters measured, with the opposite trends to those predicted often occurring. Plant biomass, canopy structure and epiphyte biomass appear to be a result of several site-specific factors that are not fully understood at this time. The results of the present study have significant implications for making generalised predictions and for monitoring A. antarctica on urbanised coasts, and will also be useful for informing ecological studies on plant–epiphyte and plant–animal interactions in A. antarctica ecosystems.
22
Duque, Maria Rosa. „Using Heat Flow Density Values Obtained in the Gulf of Cadiz and Gorringe Bank, Atlantic Ocean“. IOP Conference Series: Earth and Environmental Science 906, Nr. 1 (01.11.2021): 012113. http://dx.doi.org/10.1088/1755-1315/906/1/012113.
Der volle Inhalt der QuelleAnnotation:
Abstract The geothermal heat flow measured at the surface of the Earth is originated by different heat sources located at different depths of the planet. The main sources of heat flow in the crust are associated with radioactive decay of Uranium, Thorium and Potassium, in rocks. In some regions, additional heat sources must be considered such as exothermic chemical reactions. The value of the heat flow coming from deep regions, designated by “heat from the mantle”, must be obtained using indirect methods. In this work, the geoid height was used as indicator of alterations “in heat from the mantle” values, considering that the density decrease in regions with geoid height increase is related to high temperature values in the upper part of the mantle. The region on study is located in the Atlantic Ocean, SW of Cape St. Vincent and Cadiz Gulf. Temperature-depth values were obtained in twelve points of the region considering heat flow by conduction in the vertical direction, using published heat flow and thermal conductivity data. Layered models were made using data obtained in published seismic profiles. Moho depth values were used as lower boundary of the crust and mantle heat flow variations were made according geoid height increases. Ocean depth values between 2.5 and 4.3 km were used. A value of 5°C was used for temperature at the upper boundary (ocean bottom) of the models. Temperature calculus stops when a value of 1350 °C was attained. Lithosphere thickness is obtained considering this temperature value as temperature at the bottom of the lithosphere. Heat flow density values from 36 to 65.8 mW m−2 were used in the work with “heat from the mantle” values from 33 to 35 mw m−2. Curie Point Temperature (600°C) depths from 33 to 36 km were obtained. Lithosphere thickness values about 97 km were obtained in all the models.
23
Fowler, A. J., C. Huveneers und M. T. Lloyd. „Insights into movement behaviour of snapper (Chrysophrys auratus, Sparidae) from a large acoustic array“. Marine and Freshwater Research 68, Nr. 8 (2017): 1438. http://dx.doi.org/10.1071/mf16121.
Der volle Inhalt der QuelleAnnotation:
Snapper is a significant fishery species in Australasia whose movement behaviour remains poorly understood. This was addressed in the present study at the within-region scale using acoustic telemetry in the Gulf St Vincent, South Australia. Over 3 years from May 2011, 54 snapper were monitored throughout ~160km2 using 41 acoustic receivers. The dispersion of >500000 detections varied in space and time, reflecting three types of space use, dependent on different types of movement behaviour. One station, near a large shipwreck, accounted for 67.8% of all detections, particularly during winter, when fish were sedentary and site attached. In spring, the fish dispersed throughout the study area to different habitats and, through summer, occupied different larger restricted areas than used in winter. Snapper were highly mobile and demonstrated systematic behaviour at several temporal scales. They moved linear distances of up to ~100km and could achieve tens of kilometres in a day in episodic movements. Through the year, their activity was distributed across areas of hundreds of square kilometres. The regional spatial management regimen was assessed against this enhanced understanding of movement behaviour. A new marine park sanctuary zone that encompassed the shipwreck was appropriately located, but possible benefits of a nearby spatial spawning closure area appear limited.
24
Jost, Anne, Sophie Violette, Jean-Claude Macquar und Gilles Dromart. „Fluid palaeo-circulation generated by the Pyrenean orogeny and its potential role in the formation of lead-zinc deposits in the Cévennes region: a modelling approach“. Bulletin de la Société Géologique de France 175, Nr. 4 (01.07.2004): 317–29. http://dx.doi.org/10.2113/175.4.317.
Der volle Inhalt der QuelleAnnotation:
Abstract Recent studies of the host rock palaeomagnetism of the lead-zinc deposits on the Cévennes margins pointed towards regional fluid circulation from the early to middle Eocene. The hypothesis has therefore been put forward that mineralising fluids might have migrated as a consequence of the Pyrenean uplift. Based on this assumption, a digital model was developed to describe this palaeo-circulation along two reconstituted cross-sections, in early Eocene times. One of them extends from the Gulf of Lion to the Les Malines deposits at the southern end of the Cévennes mountains; the other one connects the Montagne Noire to Les Malines in order to test the hypothesis of a more localised fluid circulation. The modelling of heat and fluid circulation along these cross-sections is constrained mainly by fluid-temperature data, derived from analyses of fluid inclusions. The maximum recorded temperatures are about 150°C. The METIS code (Ecole des Mines, Paris) was used to test the transport scenarios while prescribing hydrodynamic characteristics in the series that would allow fluid flow. Gravity-driven flow is initiated at a high point, either the Montagne Noire or the Pyrenees. Drainage occurs at depth. The permeable formations concerned are: Cambrian dolomite in the cross-section beginning in the Montagne Noire, and Triassic and Liassic carbonate or sandstone formations in the other one. The fluids converge at the deposit site through faults on the margins of the Cévennes horst. The highest temperatures reproduced by the digital simulations in a steady-state regime are in the order of 80°C at the deposit site for each pathway. A sensitivity test showed that higher temperatures, in the order of 150°C, could only be reached with a heat flux of 120 mW.m−2 and by optimising such parameters as permeability, aquifer geometry and thermal conductivity. However, such a parameter set does not seem geologically feasible. The modelling demonstrates that circulation must have occurred at greater depths in the case of gravity-driven fluid flow. The most probable explanation is that the fluid migrated in the deep crustal basement and that, during its ascent along the faults bordering the Cévennes heights, it mixed with basinal brines migrating through shallower aquifers.
25
Fournier, Marc, Claude Lepvrier, Philippe Razin und Laurent Jolivet. „Late Cretaceous to Paleogene post-obduction extension and subsequent Neogene compression in the Oman Mountains“. GeoArabia 11, Nr. 4 (01.10.2006): 17–40. http://dx.doi.org/10.2113/geoarabia110417.
Der volle Inhalt der QuelleAnnotation:
ABSTRACT After the obduction of the Semail ophiolitic nappe onto the Arabian Platform in the Late Cretaceous, north Oman underwent several phases of extension before being affected by compression in the framework of the Arabia-Eurasia convergence. A tectonic survey, based on structural analysis of fault-slip data in the post-nappe units of the Oman Mountains, allowed us to identify major events of the Late Cretaceous and Cenozoic tectonic history of northern Oman. An early ENE-WSW extensional phase is indicated by synsedimentary normal faults in the Upper Cretaceous to lower Eocene formations. This extensional phase, which immediately followed ductile extension and exhumation of high-pressure rocks in the Saih Hatat region of the Oman Mountains, is associated with large-scale normal faulting in the northeast Oman margin and the development of the Abat Basin. A second extensional phase, recorded in lower Oligocene formations and only documented by minor structures, is characterized by NNE (N20°E) and NW (N150°E) oriented extensions. It is interpreted as the far-field effect of the Oligocene-Miocene rifting in the Gulf of Aden. A late E-W to NE-SW directed compressional phase started in the late Oligocene or early Miocene, shortly after the collision in the Zagros Mountains. It is attested by folding, and strike-slip and reverse faulting in the Cenozoic series. The direction of compression changed from ENE-WSW in the Early Miocene to almost N-S in the Pliocene.
26
Al-Fahmi, Mohammed, L. Cooke Michele und John C. Cole. „Modeling of the Dammam outcrop fractures: Case study for fracture development in salt-cored structures“. GeoArabia 19, Nr. 1 (01.01.2014): 49–80. http://dx.doi.org/10.2113/geoarabia190149.
Der volle Inhalt der QuelleAnnotation:
ABSTRACT The exposed Cenozoic carbonates of the Dammam Dome are studied to: (1) characterize fractures and associated structures; (2) interpret the fracture mechanism; and (3) gain insights into fracture development within dome-like structures in the subsurface of the Arabian Gulf region. The fieldwork is integrated with structural analysis of the near-surface horizons mapped from interpretations of 3-D reflection seismic and borehole logs. Fractures are mapped from the outcrops of the middle limestone unit of the Eocene Rus Formation. The outcrops are concentrated in the central, northern and western areas of the Dammam Dome. The fractures are interpreted as opening-mode, bed-bounded joints that form orthogonal sets in most areas. The primary (older) joint set (J1) developed in long lineaments, some of which can be traced for over 300 m across entire exposures. The J1 set is found to be broadly consistent in its trend over the dome, indicating that formation of J1 fractures was systematic and not influenced by local structural anomalies (including karst collapse) formed during the Miocene to Recent. The trend of the J1 set does not correlate with the NE-SW compressional orientation of regional stresses associated with the Zagros Orogeny. Field data interpretation, allied with analysis of dome’s growth and curvature, suggest that the overall joint pattern reflects the growth of the strata as a dome. In addition, the joint density is controlled by structural position on the dome and mechanical stratigraphy. The study results provide a first-order conceptual fracture model for the subsurface reservoirs to guide future development.
27
Wilson, Brent, und Michael A. Kaminski. „Rare species of West Indian aspect in the Holocene of Liverpool Bay and their biogeographic and environmental significance“. Micropaleontology 69, Nr. 1 (2023): 103–12. http://dx.doi.org/10.47894/mpal.69.1.03.
Der volle Inhalt der QuelleAnnotation:
The Gulf Stream, although not directly responsible for the mild, temperate climate of the British Isles, transports vast quantities of water across the North Atlantic Ocean. An extension of the Caribbean-Loop-Florida current system, this strong current cools and becomes more saline by evaporation as it flows NE across the North Atlantic Ocean. Nevertheless, it is able to transport benthic foraminifera across oceanic distances, the fauna around Bermuda containing many species described from the Caribbean Sea. Examining two cores taken from the shallow middle neritic Holocene Surface Sands Formation of the temperate Liverpool Bay, England, we found rare specimens of eight species recorded also from the neritic of the tropical Caribbean and subtropical Atlantic South Shelf Provinces: Asterigerina carinata, Dyocibicides biserialis, Elphidium discoidale, Nonionoides grateloupii, Quinqueloculina lamarckiana, Reussella atlantica and Sahulia conica. We are confident in our identifications of A. carinata and E. discoidale, but suggest that these names may have been applied to several cryptospecies. Some of these may have been transported on floating phytal debris, A. carinata, which supports algal symbionts, having been recorded at abyssal depths in the eastern North Atlantic. Othersmay have been transported as small propagules (proloculi). Although there may be a constant rain of such specimens into Liverpool Bay, we conclude on the basis of their rarity that the exotic species are unlikely to be able to overwinter there. We suggest, however, that these may have potential as invasive species for Liverpool Bay as climates continue to warm. This is not the earliest instance of transport of exotic species across the North Atlantic. The Late Eocene species Asterocyclina soldadoensis has been recorded from both the southern Caribbean region and offshore Ireland.
28
Martínez-Hernández, Enrique, und Elia Ramírez-Arriaga. „Palaeocorología de angiospermas de la flora mexicana durante el Mesozoico y Terciario. Algunas evidencias palinológicas“. Botanical Sciences, Nr. 58 (27.04.2017): 87. http://dx.doi.org/10.17129/botsci.1490.
Der volle Inhalt der QuelleAnnotation:
The historical phytogeography is closely related to climatic changes and with the modifications of Ecosystems through time caused by th e p la te tecto nics. This pa lin ostratig rap hic review is the result of the surveys carried out in several sedimentary basin from Baja California to Chiapas, Mexico. The paleochorology of angiosperms in Mexican terrains began in the Lower Cretaceous (Barremian-Aptian) in the northern state of Durango, where at the "Gran Tesoro" appeared jugella sensu Srivastava ( 1994) and Tricolpites cf. T. minutus Brenner, 1963. In the same age, in Michoacán state, southern of Mexico occurred cf. Afropolis (Brenne r) Doyle et al. 1982, at Tepalcatepec Fm. Meanwhile, at the state of Puebla in the Tlayua Fm. (Aptian - Albian), the genus Retimonocolpites Pierce , 1961, as a very scarce palinomorphs in this micrite limestone. During the late Cretaceous a pantropical flora predominated on the continents, and in Mexico three palynological provinces sensu Kedves ( 1985) were recognized: 1) Normapolles province, covering north eastern basins at Coahuila and Tamaulipas with taxa belonging to the Chlorantaceae, Magnoliaceae and to extinct genus Anacolosidites; 2) Aquilapollenites province, found in the occidental part of Mexico at Baja California and Sonora, characterized - besides Aquilapollenites- by the presence of certains paratropical taxa as Gunnera and bombacaceas; 3) Monocolpates province , present at Chiapas with high frequencies of sulcate pollen grains and Proteaceae. In Mexico through the Paleogene -from Baja California to Chiapas- the prevailing flora is pantropical with taxa belonging to the Caesalpinaceae, Bombacaceae, Sapindaceae and Sapotaceae; with a great abundance and diversity of Engelhardtia (Momipiles) together with the presence of boreal and temperate taxa. In the Eocene-Oligocene began the formations of the several types of vegetation, which in mexican territory can be considered two main provinces: one occidental province(Rocky Mountain type) with affinities with western United States and Asia and other eastern province, herein named as the Gulf Coast Province, with more para tropical elements in the northern part and which affinities are with the atlantic flora of Europa and North America (Mississippi embayments); meanwhile in the southern region of this eastern province, there is an increase in the frecuency of neotropical taxa. Finally in the Neogene, the conformation of the present mosaics of vegetations start to build during the Miocene and basically such mosaics continue until the present. Hence, at western Sonora began the establishment of the lower biomass vegetation, in contrast, in the south the neotropical floral start to be present at the coastal plains in the mexican Gulf region; meanwhile at the cordilleras the template and boreal taxa diversified i.e. Quercus and Pinus. Consequently, the mexican flora has a long history since the Early Cretaceous (120 m.a.), where the paleochorology can explain why many taxa that has been considered as neotropical, are indeed pantropical and paratropical relicts which migrated from the North as result of the climate deterioration through the Cenozoic. Other pantropical taxa evolved regionally given rise to other types of vegetation .
29
Kotthoff, U., D. R. Greenwood, F. M. G. McCarthy, K. Müller-Navarra, S. Prader und S. P. Hesselbo. „Late Eocene to middle Miocene (33 to 13 million years ago) vegetation and climate development on the North American Atlantic Coastal Plain (IODP Expedition 313, Site M0027)“. Climate of the Past 10, Nr. 4 (25.08.2014): 1523–39. http://dx.doi.org/10.5194/cp-10-1523-2014.
Der volle Inhalt der QuelleAnnotation:
Abstract. We investigated the palynology of sediment cores from Site M0027 of IODP (Integrated Ocean Drilling Program) Expedition 313 on the New Jersey shallow shelf to examine vegetation and climate dynamics on the east coast of North America between 33 and 13 million years ago and to assess the impact of over-regional climate events on the region. Palynological results are complemented with pollen-based quantitative climate reconstructions. Our results indicate that the hinterland vegetation of the New Jersey shelf was characterized by oak–hickory forests in the lowlands and conifer-dominated vegetation in the highlands from the early Oligocene to the middle Miocene. The Oligocene witnessed several expansions of conifer forest, probably related to cooling events. The pollen-based climate data imply an increase in annual temperatures from ∼11.5 °C to more than 16 °C during the Oligocene. The Mi-1 cooling event at the onset of the Miocene is reflected by an expansion of conifers and mean annual temperature decrease of ∼4 °C, from ∼16 °C to ∼12 °C around 23 million years before present. Relatively low annual temperatures are also recorded for several samples during an interval around ∼20 million years before present, which may reflect the Mi-1a and the Mi-1aa cooling events. Generally, the Miocene ecosystem and climate conditions were very similar to those of the Oligocene. Miocene grasslands, as known from other areas in the USA during that time period, are not evident for the hinterland of the New Jersey shelf, possibly reflecting moisture from the proto-Gulf Stream. The palaeovegetation data reveal stable conditions during the mid-Miocene climatic optimum at ∼15 million years before present, with only a minor increase in deciduous–evergreen mixed forest taxa and a decrease in swamp forest taxa. Pollen-based annual temperature reconstructions show average annual temperatures of ∼14 °C during the mid-Miocene climatic optimum, ∼2 °C higher than today, but ∼1.5 °C lower than preceding and following phases of the Miocene. We conclude that vegetation and regional climate in the hinterland of the New Jersey shelf did not react as sensitively to Oligocene and Miocene climate changes as other regions in North America or Europe due to the moderating effects of the North Atlantic. An additional explanation for the relatively low regional temperatures reconstructed for the mid-Miocene climatic optimum could be an uplift of the Appalachian Mountains during the Miocene, which would also have influenced the catchment area of our pollen record.
30
Jolivet, Laurent, Armel Menant, Vincent Roche, Laetitia Le Pourhiet, Agnès Maillard, Romain Augier, Damien Do Couto, Christian Gorini, Isabelle Thinon und Albane Canva. „Transfer zones in Mediterranean back-arc regions and tear faults“. BSGF - Earth Sciences Bulletin 192 (2021): 11. http://dx.doi.org/10.1051/bsgf/2021006.
Der volle Inhalt der QuelleAnnotation:
Slab tearing induces localized deformations in the overriding plates of subduction zones and transfer zones accommodating differential retreat in back-arc regions. Because the space available for retreating slabs is limited in the Mediterranean realm, slab tearing during retreat has been a major ingredient of the evolution of this region since the end of the Eocene. The association of detailed seismic tomographic models and extensive field observations makes the Mediterranean an ideal natural laboratory to study these transfer zones. We review in this paper the various structures in back-arc regions differential retreat from the Alboran Sea to the Aegean-Anatolian region and discuss them with the help of 3D numerical models to better understand the partitioning of deformation between high-angle and low-angle faults, as well as the 3-D kinematics of deformation in the middle and lower crusts. Simple, archetypal, crustal-scale strike-slip faults are in fact rare in these contexts above slab tears. Transfer zones are in general instead wide deformation zones, from several tens to several hundred kilometers. A partitioning of deformation is observed between the upper and the lower crust with low-angle extensional shear zones at depth and complex association of transtensional basins at the surface. In the Western Mediterranean, between the Gulf of Lion and the Valencia basin, transtensional strike-slip faults are associated with syn-rift basins and lower crustal domes elongated in the direction of retreat (a-type domes), associated with massive magmatic intrusions in the lower crust and volcanism at the surface. On the northern side of the Alboran Sea, wide E-W trending strike-slip zones in the brittle field show partitioned thrusting and strike-slip faulting in the external zones of the Betics, and E-W trending metamorphic core complexes in the internal zones, parallel to the main retreat direction with a transition in time from ductile to brittle deformation. On the opposite, the southern margin of the Alboran Sea shows short en-échelon strike-slip faults. Deep structures are not known there. In the Aegean-Anatolian region, two main tear faults with different degrees of maturity are observed. Western Anatolia (Menderes Massif) and the Eastern Aegean Sea evolved above a major left-lateral tear in the Hellenic slab. In the crust, the differential retreat was accommodated mostly by low-angle shear zones with a constant direction of stretching and the formation of a-type high-temperature domes exhumed from the middle and lower crust. These low-angle shear zones evolve through time from ductile to brittle. On the opposite side of the Aegean region, the Corinth and Volos Rift as well as the Kephalonia fault offshore, accommodate the formation of a dextral tear fault. Here, only the brittle crust can be observed, but seismological data suggest low-angle shear zones at depth below the rifts. We discuss the rare occurrence of pure strike-slip faults in these contexts and propose that the high heat flow above the retreating slabs and more especially above slab tears favors a ductile behavior with distributed deformation of the crust and the formation of low-angle shear zones and high-temperature domes. While retreat proceeds, aided by tears, true strike-slip fault system may localize and propagate toward the retreating trench, ultimately leading to the formation of new plate boundary, as shown by the example of the North Anatolian Fault.
31
Mousavi, Naeim, und Javier Fullea. „3-D thermochemical structure of lithospheric mantle beneath the Iranian plateau and surrounding areas from geophysical–petrological modelling“. Geophysical Journal International 222, Nr. 2 (28.05.2020): 1295–315. http://dx.doi.org/10.1093/gji/ggaa262.
Der volle Inhalt der QuelleAnnotation:
SUMMARY While the crustal structure across the Iranian plateau is fairly well constrained from controlled source and passive seismic data, the lithospheric mantle structure remains relatively poorly known, in particular in terms of lithology. Geodynamics rely on a robust image of the present-day thermochemical structure interpretations of the area. In this study, the 3-D crustal and upper mantle structure of the Iranian plateau is investigated, for the first time, through integrated geophysical–petrological modelling combining elevation, gravity and gravity gradient fields, seismic and petrological data. Our modelling approach allows us to simultaneously match complementary data sets with key mantle physical parameters (density and seismic velocities) being determined within a self-consistent thermodynamic framework. We first elaborate a new 3-D isostatically balanced crustal model constrained by available controlled source and passive seismic data, as well as complementary by gravity data. Next, we follow a progressively complex modelling strategy, starting from a laterally quasi chemically homogeneous model and then including structural, petrological and seismic tomography constraints. Distinct mantle compositions are tested in each of the tectonothermal terranes in our study region based on available local xenolith suites and global petrological data sets. Our preferred model matches the input geophysical observables (gravity field and elevation), includes local xenolith data, and qualitatively matches velocity anomalies from state of the art seismic tomography models. Beneath the Caspian and Oman seas (offshore areas) our model is defined by an average Phanerozoic fertile composition. The Arabian Plate and the Turan platform are characterized by a Proterozoic composition based on xenolith samples from eastern Arabia. In agreement with previous studies, our results also suggest a moderately refractory Proterozoic type composition in Zagros-Makran belt, extending to Alborz, Turan and Kopeh-Dagh terranes. In contrast, the mantle in our preferred model in Central Iran is defined by a fertile composition derived from a xenolith suite in northeast Iran. Our results indicate that the deepest Moho boundary is located beneath the high Zagros Mountains (∼65 km). The thinnest crust is found in the Oman Sea, Central Iran (Lut Block) and Talesh Mountains. A relatively deep Moho boundary is modelled in the Kopeh-Dagh Mountains, where Moho depth reaches to ∼55 km. The lithosphere is ∼280 km thick beneath the Persian Gulf (Arabian–Eurasian Plate boundary) and the Caspian Sea, thinning towards the Turan platform and the high Zagros. Beneath the Oman Sea, the base of the lithosphere is at ∼150 km depth, rising to ∼120 km beneath Central Iran, with the thinnest lithosphere (<100 km) being located beneath the northwest part of the Iranian plateau. We propose that the present-day lithosphere–asthenosphere topography is the result of the superposition of different geodynamic processes: (i) Arabia–Eurasia convergence lasting from mid Jurassic to recent and closure of Neo-Tethys ocean, (ii) reunification of Gondwanian fragments to form the Central Iran block and Iranian microcontinent, (iii) impingement of a small-scale convection and slab break-off beneath Central Iran commencing in the mid Eocene and (iv) refertilization of the lithospheric mantle beneath the Iranian microcontinent.
32
Mark M. Jiang. „Middle Eocene Through Basal Miocene Sequence Biostratigraphy of the Western Gulf Coastal Region: ABSTRACT“. AAPG Bulletin 78 (1994). http://dx.doi.org/10.1306/a25feecd-171b-11d7-8645000102c1865d.
Der volle Inhalt der Quelle
33
Craddock, William H., James L. Coleman und Andrew R. C. Kylander‐Clark. „Detrital zircon age spectra of middle and upper Eocene outcrop belts, U.S. Gulf Coast region“. Basin Research, 30.06.2020. http://dx.doi.org/10.1111/bre.12464.
Der volle Inhalt der Quelle
34
KASIŃSKI, Jacek Robert, Regina KRAMARSKA, Barbara SŁODKOWSKA, Vadim SIVKOV und Marcin PIWOCKI. „Paleocene and Eocene deposits on the eastern margin of the Gulf of Gdańsk (Yantarny P-1 borehole, Kaliningrad region, Russia)“. Geological Quarterly 64, Nr. 1 (02.03.2020). http://dx.doi.org/10.7306/gq.1513.
Der volle Inhalt der Quelle