Subsurface Geology and Paleodepositional Environments of Pleistocene Trend; South High Island and South Galveston Area--a Regional Evaluation: ABSTRACT

Abstract

The Pliocene-Pleistocene producing trend of South Galveston and South High Island areas represents a matured province with excellent data control. Four biostratigraphic working units (upper Pleistocene-Trimosina A, middle Pleistocene--Angulogerina B, lower Pleistocene-Lenticulina I, and upper Pliocene-Valvularia H) were regionally established and interpreted using all nonconfidential electric well logs. These correlations were verified with seismic data. Geophysical verification was possible in the upper and middle Pleistocene, but limited to local areas in the lower Pleistocene. Three major growth-fault systems, which become larger southward and attain as much as 4,000-5,000 ft of growth, were recognized. Salt piercement structures are sparse north of Federal Block HI-49 but increase in number southward. Paleoecological data and lithological information obtained from SP logs indicate that sedimentary sequences steadily prograded south from the Pliocene through Pleistocene, reaching the most southward position during the time of Trimosina A. Deposition of Pliocene-Pleistocene sand sequences occurred primarily in low-energy deltaic and associated environments. Occasional intraslope basinal and deep-water submarine fan type and bodies were also recognized. The morphology and occurrence of deltas were significantly influenced by paleotopography and salt tectonics. End_of_Article - Last_Page 299------------