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.
Results
Showing 1 to 20 of 124 for “"unconformity"”.
-
The Middle Ordovician Knox unconformity, Virginia Appalachians: transition from passive to convergent margin
The Knox unconformity in the central and southern Appalachians is developed on Lower to early Middle Ordovician Knox/Beekmantown carbonates. The unconformity marks the transition from Cambro-Ordovician shelf carbonate deposition on a passive margin to carbonate and clastic deposition in a foreland …
-
Regional cementation associated with unconformity-sourced aquifers and burial fluids, Mississippian Newman Limestone, Kentucky
Aquifer-related cements may be differentiated from deeper burial cements by trace elements, cathodoluminescence, staining, and fluid inclusion analysis in the Mississippian Newman Limestone, eastern Kentucky. Aquifer cements are nonferroan, and show a nonluminescent to dull to nonluminescent to …
-
Geologic Factors Affecting Hydrocarbon Occurrence in Paleovalleys of the Mississippian-Pennsylvanian Unconformity in the Illinois Basin
… associated with the Mississippian-Pennsylvanian unconformity have been identified as potential targets for hydrocarbon exploration in the Illinois Basin. Though there is little literature addressing the geologic factors controlling hydrocarbon accumulation in sub-Pennsylvanian paleovalleys …
-
Geochemical modeling of diagenesis, hydrothermal alteration, and unconformity-related uranium mineralization in the Athabasca Basin, Saskatchewan, Canada
Unconformity-related uranium (URU) deposits in the Athabasca Basin were interpreted to have formed through interactions between oxidizing basinal fluids and reducing basement-derived fluids or basement lithologies under diagenetic-hydrothermal conditions. However, there is controversy regarding …
-
URANYL DEPOSITION IN UNCONFORMITY-RELATED DEPOSITS IN THE ATHABASCA BASIN: EVIDENCE FROM URANIUM SPECIATION IN HEMATITE AND GOETHITE
… basin (Canada) occurred are often not clear. The unconformity-related uranium deposits in the Athabasca basin are commonly accompanied by extensive and intensive hematite-rich alteration halos. Previous U L3-edge XANES studies of uranium-bearing fluid inclusions and thermodynamic modeling …
-
Beekmantown Formation-Middle Ordovician limestone unconformity on the northwest limb of the Green Ridge anticline near Fincastle, Virginia
The depositional and erosional history can be summarized as follows: 1) Subtidal carbonate shelf sedimentation through Early Ordovician (and including early Middle Ordovician White Rock?) time represented by the Beekmantown Formation. 2) Emergence of a Beekmantown terrain due to eustatic lowering …
-
Petrology and Weathering Environment of Sub-unconformity Limestone unit: The Kessler Limestone member of the Bloyd Formation, Morrowan (Pennsylvanian) Northwest Arkansas
… Member and the Trace Creek is a regional unconformity in the midcontinent, marked by a manganese-enriched crust filled with various nodules and concretions. Methods used in this study began with reviews of previous investigations of the Kessler Limestone and followed with a petrographic …
-
An unconformity in the Carolina slate belt of central North Carolina: new evidence for the areal extent of the ca. 600 Ma Virgilina deformation
… suggested by Glover (1974), that an angular unconformity separates the older volcanic strata of the Virgilina sequence from the younger units of the central N.C. sequence. The presence of an unconformity is indicated by 1) the truncation of lithologies comprising the Hyco Formation at the …
-
Spatial and Temporal Variations in Composition and P-T Conditions of Ore-Forming Fluids Along Structures Controlling Unconformity-Related Uranium Deposits in the Athatbasca Basin, Saskatchewan
Unconformity-related uranium (URU) deposits in the Athabasca Basin occur within certain segments of basement-rooted reverse faults near the basin-basement unconformity. It is widely accepted that these deposits formed through interaction between oxidized basinal fluids and reduced basement-derived …
-
The micropaleontology and stratigraphy of the subsurface "Heath" formation (Mississippian-Pennsylvanian) of western North Dakota
… by locally petroliferous sandstone units. An unconformity, indicated by a conglomeratic horizon, separates the lower two from the upper three units.</p> <p>The fauna of the “Heath” Formation includes non-marine ostracodes, with which this study is primarily concerned, and non-marine pelecypods …
-
Sedimentary basin evolution and structural compartmentalization in the northernmost Andes : Eastern Cordillera and Magdalena Valley, Colombia
… that pre-date and post-date an Eocene regional unconformity. The contrasting sedimentary successions above and below the unconformity define a major shift from organic-rich clastic marine deposition of regional extent to more localized coarse-grained fluvial and alluvial fan deposition with …
-
DEVELOPMENT OF THE ROCKY MOUNTAIN FORELAND BASIN: COMBINED STRUCTURAL, MINERALOGICAL, AND GEOCHEMICAL ANALYSIS OF BASIN EVOLUTION, ROCKY MOUNTAIN THRUST FRONT, NORTHWEST MONTANA
The sub-Middle Jurassic unconformity exhumed at Swift Reservoir, in the Rocky Mountain thrust belt of Montana, exposes structures that call for a re-evaluation of the deformation history at this locale. The unconformity separates Late Mississippian Madison Group carbonate (~340 Ma) from the …
-
DEVELOPMENT OF THE ROCKY MOUNTAIN FORELAND BASIN: COMBINED STRUCTURAL, MINERALOGICAL, AND GEOCHEMICAL ANALYSIS OF BASIN EVOLUTION, ROCKY MOUNTAIN THRUST FRONT, NORTHWEST MONTANA
The sub-Middle Jurassic unconformity exhumed at Swift Reservoir, in the Rocky Mountain thrust belt of Montana, exposes structures that call for a re-evaluation of the deformation history at this locale. The unconformity separates Late Mississippian Madison Group carbonate (~340 Ma) from the …
-
Determination of Heterogeneity by High-Resolution Seismic Reservoir Characterization in the Heavy Oil Temblor Reservoir of Coalinga Field, California
… in southwestern corner below the Top Temblor unconformity shifts towards ESE-SE with depth, and runs nearly parallel to the Top Temblor unconformity. It cuts across the Valv unconformity in central part creating a channel incision, and follows the Buttonbed unconformity towards the north. The …
-
Geometric and hydrodynamic modelling of fluid-structural relationships in the southeastern Athabasca Basin, Saskatchewan, Canada, with implications for uranium ore genesis
The high-grade unconformity-related uranium deposits in the Athabasca Basin in northern Saskatchewan, Canada, generally show close spatial relationships with reactivated basement faults. However, the nature of this relationship has not been well understood. This thesis aims to address this problem …
-
Integrating apatite (U-Th)/He and fission track dating for a comprehensive thermochronological analysis: refining the uplift history of the Teton Range
… that doming of the Precambrian-Paleozoic unconformity occurred prior to ~50 Ma. However, by ~15 Ma, rapid cooling of the Mount Moran section essentially "flattened" the unconformity. Thus, the modern domed shape is a result of displacement across the Teton fault, allowing the unconformity …
-
A Potential Long-lived Upper Cretaceous Paleodrainage System In The U.s. Southwestern Georgia-southeastern Alabama Region
<p>The Gulf Coastal Plain unconformity separates crystalline basement of the Appalachian core from sedimentary units of the Coastal Plain. In the Columbus, Georgia region, basement rocks of the Uchee terrane are typically overlain by sands and gravels of the Tuscaloosa Formation. Sediments within …
-
The integration of petrologic and isotopic data from the Boulder Conglomerate to determine the age of the Navan orebody, Ireland
… Beds Ore, is truncated by the fault-generated unconformity and is reworked as clasts and matrix into the basal Boulder Conglomerate. Matrix-deficient breccia beds deposited on the unconformity possess mineralisation as cement to interclast porosity. This cement is contiguous with replacement …
-
Fluid Evolution and Structural Control on Uranium Deposits in Successor Basins in Northern Canada and Northern Australia
… at ca. 1.62 Ga corresponding to the timing of unconformity-type U mineralization in the overlying Athabasca Basin. The main breccia-type U mineralizing event that affected all deposits in the Beaverlodge area formed at ca. 1.85 Ma from metamorphic fluids at ca. 330oC linked to metasomatism …
-
Eocene to Miocene geology of southwest Viti Levu, Fiji
… mid-Oligocene. They are overlain with 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, …
Page 1 of 7