Reactivation of Fault Movement, Tepetate Fault Zone, South-Central Louisiana: ABSTRACT

The Tepetate fault zone consists of a series of faults trending east-west along the northern margin of the South Louisiana salt dome basin. The fault is known to be currently active in the Baton Rouge area, where it has fractured and displaced pavement and foundations. Detailed subsurface mapping of the fault zone in an area of Pointe Coupee Parish to the west reveals that there have been two distinct periods of growth faulting, separated by a long period of inactivity. The first period of fault activity occurred during the time from Wilcox (or earlier) to Frio deposition. There then followed a period of quiescence characterized by deposition of nearly 8,000 ft (2,400 m) of fluvial sands and shales, primarily of Miocene age. In more recent times, probably Pleistocene, the fault has been reactivated, and up to 40 ft (12 m) of additional displacement has occurred in the area studied. Of concern is the fact that a site near this fault has been proposed for the surface and subsurface disposal of hazardous wastes. Recognition of the interruption and reactivation of growth faulting in south Louisiana is of considerable importance with regard to problems of regional structural evolution, fluid migration, and the siting of surface and subsurface waste-disposal facilities. Because of difficulties in subsurface correlation, faults of small displacement in fluvial sequences can easily be overlooked. Further detailed study, however, is warranted. End_of_Article - Last_Page 1431------------