Geophysical and Geological Investigation of Buried Triassic(?) Rift Basin in Coastal Plain of South Carolina
William A. Smith, Pradeep Talwani, Donald J. Colquhoun
The recognition and interest in the eastern United States Triassic rift basins as potential exploration frontier areas for hydrocarbons have effected a systematic process to define the configurational extent and limit of the structural development of the basins.
Of particular interest in South Carolina is a large southwest-northeast-trending Triassic(?) graben, which is located beneath 0.5-1.0 km of coastal plain sediments. The gross configuration of the basin has initially been recognized from interpretation of aeromagnetic and gravity maps. Initial findings indicate that the basin is approximately 20-50 km wide and that the boundary or flank structures are not well constrained or understood.
We have conducted an extensive study of the northern boundary and flank of the southwest-northeast-trending Triassic basin, to ameliorate the disposition of the boundary structures. This study uses data from a detailed gravity survey, which consists of approximately 3,100 stations with spacing on the order of 1.0-1.5 km, six refraction lines, detailed aeromagnetic data, seismicity studies, shallow borehole stratigraphy data, and geomorphic features.
Geophysical data reveal a series of northwest- and northeast-trending features, which we interpreted as indicative of a complexly faulted basement with en echelon faults and smaller grabens (subbasins?) proximal to the large southwest-northeast-trending rift basin. Shallow stratigraphic borehole data, surficial geomorphic feature trends (rivers and streams), and channel characteristics also indicate correlation with the geophysical and interpretative geologic features.
The multifaceted study of the flank of this rift basin indicates significantly enhanced boundary or flank structures, which are essential for a feasible exploration of this rift basin in South Carolina.
AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.