Late Pleistocene Geologic History of Texas Outer Continental Shelf and Upper Continental Slope: 4. Character of the Sediments

Integrated high-resolution seismic and core data from the Texas outer continental shelf and upper continental slope were used to reconstruct the late Pleistocene geologic history of the area. Paleoclimatic fluctuations, determined with foraminifers and correlated with the aid of seismic data, indicate that the late Pleistocene-Holocene sequence represents five cool/warm fluctuations Correlation of these fluctuations with the generalized paleotemperature curve generated from oxygen isotope data serves as a basis for placing both paleoclimatic and sedimentary events into a time framework. Seismic profiles over core sites allow the dating of seismic reflecting horizons and extension of the chronologic framework over most of the area. Two major phases of shelf-edge outbuilding occurred during the late Pleistocene. Both phases began with the development of shelf-margin deltas during lowstands of sea level. The deposition of these shallow-water clays and sandy clays within the shelf-slope transition zone was accompanied by active growth faulting. Large slide masses are present on the adjacent continental slope where the progradation of shelf-margin deltas extended beyond the previously existing shelf break. Active gas generation appears to be associated with the slide masses and greatly alters the seismic character of the surrounding sediments.