Browsing by Subject "seismic stratigraphy"
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Item 3-D structural and seismic stratigraphic interpretation of the Guasare-Misoa Interval, VLE 196 Area, Block V, Lamar Field, Lake Maracaibo, Venezuela(Texas A&M University, 2004-09-30) Arzuman, SadunIn this study, the structure, depositional system, and the seismic stratigraphy of the VLE 196 area, Block V in Lamar Field were interpreted using 3-D seismic data and well logs to characterize structural and depositional settings of the Guasare-Misoa interval. To demonstrate structural settings of the study area 3-D seismic data were interpreted. Three main seismic reflectors, which are the Late Eocene unconformity, Guasare, and La Luna formations, were picked. The most dominant structure in the area is the VLE 400 Fault which was interpreted as a left-lateral strike-slip reverse fault due to its behaviors as a reverse fault in cross sections and as a strike-slip fault in strike sections. The VLE 400 Fault subdivides the VLE 196 area into two main structural blocks, a downthrown block in the western part and the upthrown block in the eastern part of the field where the hydrocarbons were trapped. Several en echelon normal and reverse faults were located along the both sides of the area. The main importance of these faults are that they fractured the La Luna source rock and created migration pathways through the reservoir layers of the Misoa Formation. To interpret depositional system of the Guasare-Misoa interval, tops of the C4 and C5 intervals and associated C4 layers were picked based on well logs and lithofacies maps were prepared. The results of this part of the study show that the sandstones of the Misoa Formation are delta front and fluvial/distributary channel facies of delta system. The net sand thickness map of the C4 interval also exhibits southeast northwest contour patterns reflecting depositional axes in the area. Shaly units of the C4 interval interpreted as potential seals and are of variable thickness and extend. Seismic stratigraphic interpretation of the area shows that the four main seismic facies are dominant which mainly represent the recent sediments, "C" sands of the Misoa Formation, underlying Colon and Mito Juan shales, and basement respectively. Some distributary eroded channel fill structures were also observed within the Misoa Formation, but they were not continuous through the area because of the intensive faulting.Item The Seismic Stratigraphy and Sedimentation along the Ninetyeast Ridge(2010-10-12) Eisin, Amy ElizabethThe Ninetyeast Ridge (NER) is a ~5000 km-long aseismic volcanic ridge trending NS in the eastern Indian Ocean basin. It is widely accepted that NER formed from the trace of a single hotspot as the Indian plate moved northward during the Late Cretaceous and Early Cenozoic due to the linear age progression from 43 Myo at the southern end to 77 Myo at the northern end. What is not fully understood is the geologic history of the ridge since its formation. This study examines the stratigraphy and sediment thickness on the ridge using new seismic data to describe the sedimentary history of NER. More than 3700 km of 2D multichannel seismic reflection profiles were collected along NER at seven sites between 5.5 degrees N and 26.1 degrees S during cruise KNOX06RR of the R/V Roger Revelle in 2007. Scientific objectives were to obtain site survey data for proposed drilling and to understand the sedimentary layers, sediment distribution, and geologic history of NER. Seismic survey sites were chosen primarily based on proximity to existing Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) drill holes (Sites 758, 216, 214, and 253) for interpretation and correlation with existing lithologic data. Seismic data were processed (filtered, stacked, and time-migrated) and interpreted using standard seismic stratigraphy principles. Three major horizons were interpreted, correlated with those previously recognized at the DSDP and ODP sites, and traced throughout the seismic data. Seismic data were categorized into three units based on distinct acoustic properties including changes in reflector amplitude, wavelength, continuity, and geometry. Seismic Unit I comprises a succession of pelagic sediments and sedimentary rock draped over Seismic Unit II, which consists of pelagic carbonates mixed with volcaniclastics. Seismic Unit III is volcanic basement. Sediment layer thicknesses and distribution were mapped at each site, and bathymetric data were correlated with seismic data to interpret geologic features. Seismic and core data indicate a common sedimentary history at each site: volcaniclastic-rich sediments deposited during or shortly after ridge formation topped by a thick drape of pelagic sediments. This history likely happened in three stages over the last ~77 My: 1) the initial subaerial or submarine emplacement of the volcanic ridge, 2) the deposition of shallow water sediments and volcaniclastics, and finally 3) the subsidence of the ridge followed by deep water pelagic sediment deposition.