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Showing 1 to 20 of 40 for “"Unconformities"”.
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Karoo-Etendeka Unconformities in NW Namibia and their Tectonic Implications
In north-western Namibia the fills of the Karoo-Etendeka depositories can be subdivided into (1) a Carboniferous-Permian, (2) a Triassic-Jurassic and (3) a Cretaceous megasequence, each recording extensional periods related to successive rifting phases in the evolving South Atlantic. The tectonic …
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Evolution of the Onion Creek salt diapir and related sediment filled salt-withdrawal basins during the Plio-Pleistocene: analysis of growth strata and progressive unconformities, Grand County, Utah
Includes bibliographical references (leaves 86-88).
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Determination of Heterogeneity by High-Resolution Seismic Reservoir Characterization in the Heavy Oil Temblor Reservoir of Coalinga Field, California
… marine to near-shore fluvial. Moreover, two unconformities dissect the reservoir interval. The seismic dataset exhibits erratic, distorted reflection strengths and amplitudes caused by steam-injection-aided production. A petrophysical analysis based on Gassmann fluid substitution suggests a …
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Reevaluation of the southwestern end of the Salem synclinorium
… Ordovician/Silurian and Silurian/Devonian unconformities have removed more section from the southern portion of the synclinorium which has been interpreted as evidence of a more landward setting for this area. Previous interpretations of these coarser sediments and unconformities theorized …
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Caracterização das unidades sísmicas, processos sedimentares e idade do cânion Almirante Câmara, bacia de Campos
… in this basin. Five seismic units separated by unconformities were identified in the continental slope and among these unconformities were the Marco Cinza. The area of the lobe in which the canyon is located was divided in 4 different sections that can be distinguished by theirs seismic …
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Mid- to Late-Paleozoic Deformation On Buck Mountain, Nevada
… episodes of folding. The structures and angular unconformities at Buck Mountain are consistent with late-Paleozoic deformation and regional unconformities documented previously elsewhere in northern and central Nevada.Folds in the Morrowan-Atokan Ely Limestone are erosionally truncated and …
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Seismic sequence stratigraphy of the Lower Congo, Kwanza, and Benguela Basins, offshore Angola, Africa
… Basins, was interpreted. Sequences and their unconformities were correlated within each basin as well as between basins. Major sequences could be interpreted throughout and between the three basins with a high degree of confidence. Additional sequences within these major sequences were …
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The Middle Ordovician Knox unconformity, Virginia Appalachians: transition from passive to convergent margin
… in Virginia. Development of regional unconformities on shelf sequences of passive margins immediately beneath foreland basin sequences is common in other orogens, reflecting gentle warping of the shelf prior to foundering beneath synorogenic clastics. Such unconformities may localize …
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Deep sea seismic stratigraphy
… such as abrupt lithological changes and unconformities, in the two different realms are not neccessarily produced by the same processes. It is the nature of these processes which control the chronostratigraphic significance of a reflector. Thus reflectors may be correlated with reference …
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Paleontology and stratigraphy of the Niobrara Formation (Upper Cretaceous) of eastern North Dakota with emphasis on the calcareous nannoplankton
… upper shaly chalk. The formation is bounded by unconformities that exhibit considerable relief. In a central area, thick Niobrara was deposited in a northwest-trending channel eroded into the underlying Carlile Shale. Numerous diastems were recognized within the formation on the basis of …
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Characterizing the deformation history of the southern Mina Deflection: field and structural studies in the Huntoon Mountains, California-Nevada
… faults that cut all units in the HMA and offset unconformities between Miocene volcanic rocks and Pliocene basalt lavas. Offset unconformities record a minimum total Pliocene ENE sinistral and NW dextral slip rates of 0.8 ± 0.4 mm/yr and 0.3 ± 0.1 mm/yr, respectively. Summing our new ENE …
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Stratigraphy, Sedimentology and Early Diagenesis of Pennsylvanian-Permian Mixed Carbonate-Siliciclastic Cyclothems, SW Ellesmere Island, Nunavut
… sequences bounded above and below by regional unconformities. These sequences are dated as Bashkirian-Kasimovian and Gzhelian-Sakmarian based on foraminiferal biostratigraphy. Superimposed on this trend are fifth-order sequences, or cyclothems, likely resulting from glacio-eustatic …
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Tectonic subsidence analysis of the Williston Basin
… subsidence models and extrapolated across unconformities to evaluate continuous subsidence models. Extrapolated tectonic subsidence curves near the center of the basin display a relatively constant subsidence through the Paleozoic, at a rate of slightly less than 1 cm ka-1, and then …
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Reinterpreting vintage geophysical data from the Algoa and Gamtoos Basins, South Africa: an integrated sequence stratigraphic framework since the middle Mesozoic
… tectonic system tracts models. Because subaerial unconformities (SUs) in the distal syn-rift sequence are not detectable, a diachronous, northward advancement of the shoreline until the late Valanginian can be postulated. The observations in the syn-rift sequence, which is bound by a basal SU, …
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3D seismic attribute analysis and machine learning for reservoir characterization in Taranaki Basin, New Zealand
… are implemented to identify discontinuities, unconformities, lithology, and bright spots. Algorithmic analyses are conducted using Python programming to generate and overlay the attributes which are displayed in 3D view. Integrating all of the attributes in a single 3D view significantly …
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Conodont biostratigraphy and paleoecology of the Lower Devonian Helderberg Group of Virginia
… by the Ridgeley Sandstone and its bounding unconformities. Conodonts tend to avoid tidal flat and lagoonal environments. They are not uniformly distributed through the rest of the section, but the occurrence of all but two species is not related to water depth, energy, or substrate; …
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Magnetic Characteristics of Carboniferous Continental Depositional Systems: Implications for the Recognition of Depositional Hiatuses
… periods of prolonged exposure and to define unconformities within compound valley fills.
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Evolution of tectonic and stratigraphic geometries in the Southern Outeniqua Basin
… lead to the identification of seven secondorder unconformities which have been further defined into five main seismo-stratigraphic units. The variation in major structural orientations suggest the evolution of the basin developed during three phases of extension, which have been related to the …
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Regional cementation associated with unconformity-sourced aquifers and burial fluids, Mississippian Newman Limestone, Kentucky
… appears to have been associated with post-Newman unconformities reflecting a shift to a wetter climate in Late Mississippian-Pennsylvanian time which generated regional aquifers. Aquifer cement abundance decreases away from recharge areas and is determined by staining for late burial calcite and …
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The Dynamics of the Late Neogene Antarctic Ice Sheets in the Central Ross Sea using a Multianalytical Approach
… two of which are coincident with Ross Sea Unconformities three and two. Late Miocene samples have abundant Cretaceous zircon populations, radiogenic neodymium values, and clasts interpreted as having a West Antarctic provenance. In latest Miocene samples, zircons are mostly Ross Orogeny age …
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