Deltaic Sedimentation, Salt Mobilization, and Growth Faulting in Gulf Coast Basin: ABSTRACT

Abstract

Regional facies mapping and analysis of thick, terrigenous wedges, and mapping of principal structural features (salt intrusion and growth faulting) indicate a direct relation between sedimentation and tectonics in the western Gulf basin. Proximal parts of clastic wedges infilling the basin consist of paralic, mainly deltaic, depositional systems; distal parts are made up largely of deep-water, continental-slope deposits. Two kinds of delta systems are characteristic: (1) high-constructive deltas marked by rapid, large-volume deposition; and (2) high-destructive deltas with large sand content and slower rates of accumulation. Distribution of 4 major high-constructive delta systems and associated continental-slope systems is coincident with 4 major salt-diapir fields (including about 90% of the domal salt structures of the basin). Mobilization of deep seated, bedded salt occurred by lateral migration to interdeltaic areas and by distal migration, establishing diapir fields fronting major delta systems and coincident with slope systems. Salt mobilization related to strike-depositional (barrier bar and strandplain) systems was generally as broad salt ridges rather than domes. In high-constructive deltas, growth faulting is facies coincident, forming at the boundary of delta-front sands and thick prodelta muds. As with salt mobilization, the principal tectonic grain of growth faulting developed in connection with the 4 major episodes of high-constructive wedges in the offlap filling of the basin, rejuvenating growth faulting and salt mobilization initiated by the high constructive deltas. Accordingly, direct facies correlation in distribution of growth faulting and salt mobilization occurred. End_of_Article - Last_Page 779------------