Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 62 for “"middle Miocene"”.
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Middle Miocene ostracoda from northern Iraq
… to the adjacent and related regions. Three Miocene Ostracod provinces are proposed, namely a western India province, a Zagros shelf province and a southeast Turkey province.
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Middle Miocene carbon cycle dynamics: A multi-proxy approach
… ice sheets in Antarctica happened during the middle Miocene, about 14 million years ago (Flower and Kennett, 1995; Zachos et al., 2001). The middle Miocene therefore represents one of the distinct phases of rapid change in the transition from the “greenhouse” of the Cretaceous to the …
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Sedimentological constraints on Middle Miocene extensional tectonism of the southern Las Vegas Range, southern Nevada
… model is proposed for the reconstruction of a Miocene lacustrine basin in the southern Las Vegas Range, Nevada, that was fragmented during a period of extensional tectonism. The model suggests that the sediments were deposited in an isolated basin during initiation of normal faulting in the …
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Spatial and Temporal Characterization of the Petrified Springs Fault, Central Walker Lane, Nevada: Documenting Middle Miocene Dextral Slip
… that are overlain unconformably by Oligocene and Miocene tuffs and lavas offset by the Petrified Springs fault, a northwest-southeast striking, ~65 km long, dextral fault. Four Cenozoic offset markers, three paleovalleys and one truncated normal fault, constrain the slip history of the Petrified …
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Microfacies, Depositional Environments, and Diagenesis of the Amapa Carbonates (paleocene-Middle Miocene), Foz Do Amazonas Basin, Offshore Ne Brazil
… northeast Brazil. The Amapa Formation (Paleocene-Middle Miocene) consists of a carbonate platform adjacent to a landward fluvio-deltaic system which periodically prograded over the platform. The latter became discontinuous in the central portion of the basin after the Oligocene, when transverse …
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THE STRATIGRAPHIC POSITION OF FOSSIL VERTEBRATES FROM THE POJOAQUE MEMBER OF THE TESUQUE FORMATION (MIDDLE MIOCENE, LATE BARSTOVIAN) NEAR ESPAÑOLA, NEW MEXICO
… is not well understood. This region, during the Middle Miocene, represented a dynamic alluvial fan-fluvial-lacustrine environment within the Española Basin while the Rio Grande Rift was active. Cavazza (1986) identified two paleodrainage systems (lithosome A, basin-margin facies and B, …
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Miocene herpetofaunas from the central Gulf Coast USA: their paleoecology, biogeography, and biostratigraphy
… The herpetofaunal composition of Fort Polk and Miocene east Texas localities is similar enough to Great Plains localities that they are all considered to be one biogeographical province during the Barstovian. The use of ternary diagrams, ratios of herpetological elements to kg matrix screened, …
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Eocene to Miocene geology of southwest Viti Levu, Fiji
… angular unconformity by the Upper Oligocene to Middle Miocene Wainimala Group which includes volcaniclastic turbidites, hemipelagic carbonates and vitric tuffs deposited in the Sigatoka sedimentary basin, and further south volcaniclastic rudites, intrusive/extrusive dacites and andesites, and …
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Evolution and ecology of C4 grasses: insights from carbon isotope analysis of grass pollen grains
… technique to samples from the Oligocene and Miocene in Western Europe, a region of the world with no previous documented evidence of C4 grasses, yet with climatic conditions similar to regions where C4 grasses are common today. In Oligocene samples from France, I found that >70% of total …
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Tertiary dinoflagellate, acritarch, and chlorophyte assemblages from the Oak Grove Core, Virginia Coastal Plain
… Group and the Calvert and Choptank Formations (Miocene) of the Chesapeake Group. The assemblages are composed of 176 dinoflagellate species and subspecies (82 genera), of which 20 species and subspecies and one combination are new; five acritarch species (two genera) and five chlorophyte species …
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Neogene to quaternary foraminifera from the western margin of southern Africa
… of South Africa were studied to determine the middle Miocene to Quaternary stratigraphy, palaeoenvironment and palaeoceanography of the western margin of southern Africa. Cores from the Namibian shelf recovered middle Miocene calcareous mud in erosional contact with overlying Pliocene to …
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ANTARCTIC GLACIAL CHRONOLOGY REFLECTED IN THE OLIGOCENE THROUGH PLIOCENE SEDIMENTARY SECTION IN THE ROSS SEA
… these islands in the late Oligocene and early Miocene, as evidenced by fluctuations in the percentages of IRD (ice-rafted debris) and by the occurrences of zones containing visually massive pebbly mudstones within the Ross Sea section. These ice shelves coalesced to form an ice sheet over West …
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Palynological Evidence for the Paleoenvironmental History of the Miocene Llanos Basin, Eastern Colombia
… This basin exhibits a geological section of Miocene age and the core Saltarin-1A, analyzed in this study, is the first and most complete drilling coreof this section with 680 meters. It represents to Carbonera, Leon and Guayabo Formations. Based on palynological data, this work has as its …
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The tertiary geology and systematic paleontology (phylum mollusca) of the Guajira Peninsula, Colombia, South America
… Nazareth (new). Rocks of Paleocene and Lower to Middle Eocene age are apparently not present in outcrop.</p> <p> Middle and Upper Tertiary formations in the peninsula record a transgressive-regressive marine cycle. The Upper Oligocene Sillamana Limestone suggests an initial transgression. The …
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Paleoclimate and paleoecology of Miocene Eastern African primate habitats : a multiproxy approach.
Reconstructing Miocene climate and ecosystem in eastern Africa is essential for understanding the environmental and geological contexts in which early primates evolved. Particularly, correlations between leaf size, shape, temperature, and precipitation have become a widely used tool for …
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Mixed Carbonate-Siliciclastic Sequence Development and Chemostratigraphy On a Distal Foreland During Miocene Glaciation, Eastern Saudi Arabia
The Miocene of the Lidam area, Eastern Province, Saudi Arabia, was studied to examine the interaction of glacio-esustasy during moderate Antarctic glaciation, within a small back bulge basin on the slowly subsiding distal Arabian foreland, distal from the active Zagros fold-thrust belt. Low …
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Kinematics and timing of normal faulting in a metamorphic core complex: Grouse Creek Mountains, Utah
The Middle Mountain shear zone (MMSZ) and the brittle Upper detachment, two west-dipping normal fault systems, and the 25.3 Ma Red Butte stocks are exposed in a metamorphic core complex in northwest Utah, in the central Grouse Creek Mountains. 40Ar/39Ar thermochronology and kinematic studies …
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FORAMINIFERAL COMMUNITY DYNAMICS OF THE CHESAPEAKE GROUP, CALVERT CLIFFS, MARYLAND, USA
… the Calvert Cliffs, MD were deposited during the Middle Miocene Climatic Optimum (MMCO) when global temperatures were ~3-6[degrees]C higher than present and the subsequent Middle Miocene Climatic Transition (MMCT) when global temperature dropped ~6 [degrees]C from peak temperatures of the MMCO. …
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The roof of the cyclades : a structural, stratigraphic, and paleomagnetic study of Neogene extensional tectonics in Central Greece
… the pattern of sedimentation within the Early to Middle Miocene Kymi-Aliveri basin. I date the basin fill using a combination of magnetostratigraphy and U/Pb zircon geochronometry. Through detailed mapping of the spatial variation in sedimentary facies within the basin, I relate the record of …
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Rapid Middle to Late Miocene Slip Along the Zanskar Normal Fault, Greater Himalayan Range, NW, India: Constraints from Low-Temperature Thermochronometry
… adjacent to the ZF, provide constraints on the middle Miocene to present exhumation history of the footwall. The overlap of these elevation invariant mean ZHe, AFT, and AHe thermochronometric ages, indicate rapid cooling between ~14-10 Ma. Inverse modeling of ZHe, AHe, and AFT thermochronometric …
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