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See the Theses and Dissertations Index: Dissertation abstracts published prior to may be found through Dissertations and Theses: Charles Kerans pages, 64 references The Albian Glen Rose Formation has been well known as a shallow shelf carbonate with common patch reef development along the interface between the Comanche Shelf and the Maverick Basin.
Stratigraphic analysis of 75 well logs and 7 seismic stratal slices formed the basic data for interpreting the Lower Glen Rose sequence framework and paleogeographic setting.
Buildups in unit 2 change from transgressive isolated buildups into a flat biostrome during progressive onlap. Unit 3 buildups record a landward shift relative to the biostrome of unit 2, as shown on well logs and are coincident with the sequence 7 MFS.
The third and uppermost buildup level is found in unit 4, in the late highstand of sequence 7. This unit shows a distinct seaward shift Theses and dissertations abstracts the patch reefs, relative to unit 3, consistent with the highstand interpretation.
Detailed examination of facies in the two cores available for study indicates that the patch reefs formed during shoaling of the shelf. The patch reefs are proven hydrocarbon reservoirs with gas potential concentrated in units 2 and 4. Geomorphometric analysis based on seismic stratal slices of more than 30 buildups from unit 4 determined that these are domal features with a distinct NNW-SSE elongation and steeper SW flanks.
Asymmetry of the patch reefs may be the result of NW-directed far-field paleo-currents and NNE-directed, wind-driven paleo-waves.
Independently of the size scale, the elongation axis of buildups is 1. The University of Texas at Austin, Supervisors: Stoffa and Kirk D. McIntosh pages, 73 references There is a dramatic variation in geochemical sediment tracer signal along the Central American volcanic arc.
Two contradicting theories, one supporting sediment accretion and the other subduction erosion, have been suggested as possible explanations for these variations. My goal in this dissertation is to use seismic images of the lower slope off Nicaragua and Costa Rica to study the influence of subducting plate structure on sediment dynamics.
I am particularly interested in documenting the efficiency of sediment subduction, its along strike variation, and to see if it corresponds with the geochemical anomalies. Although high quality seismic data was acquired offshore Nicaragua, it remained difficult to image the lower slope in detail with conventional processing techniques.
Several characteristics of this geologic environment pose seismic imaging problems: In this environment the common midpoint gathers do not represent a collection of true common subsurface reflection points.
An accurate velocity model is required to get a good PSDM image. Therefore one of the most important aspects of PSDM is velocity analysis. Over the last few decades, residual migration velocity analysis RMVA has been an area of active research.
Previous work on RMVA in the depth-offset domain required top down layer stripping migration in order to derive the interval velocities directly, hence making it very computationally intensive. Here I propose a new technique in which for each common image gather CIG we first create a table of offset-ray parameters-depth x-p-z using a local 1D assumption.
Then I calculate the residual migration depth corrections in the p-z domain and finally map these depth corrections back to the x-z domain using the x-p-z table.
Since I calculate the residual migration depth corrections in the p-z domain, the interval velocities are derived directly by top down residual migration.EBSCO Open Dissertations is a collaboration between EBSCO and BiblioLabs to increase traffic and discoverability of ETD research.
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