ABSTRACT

The existence and importance of horizontal salt movement and structuring on the Louisiana shelf is well defined by drilling, improved seismic technology and new understanding of salt tectonics. In this paper, we describe the extensive salt sheet provinces of the Louisiana shelf, and discuss related salt emplacement destruction, timing, associated depositional environments, and their significance for subsalt exploration.

On the northwestern Louisiana inner shelf and onshore coastal area, extensive salt sheets were extruded periodically into overlying sediments and coalesced into extensive salt canopies on the sediment-starved slope from late Eocene to early Miocene. These salt canopies were destroyed by prograding Oligocene and Miocene deltaic sediments, leaving extensive salt welds linking isolated shale ridges and salt remnants, and a large family of faults developed above the detachment. In the South Addition of the Louisiana OCS, the structural framework of the Plio-Pleistocene section exhibits a similar but more complex style along the shelf. Zones with extensive salt welds and detached large basinward-dipping families of faults dominate most of the area. They are separated by zones with isolated salt sheets and related small randomly-orientated faults. This pattern suggests uneven slope environments or, alternatively, sediment starvation and feasting during the emplacement of salt sheets from late Miocene to early Pliocene.

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