Upper Cretaceous to Lower Tertiary evaporite diapirs and evacuation structures exposed in La Popa Basin, northeast Mexico, controlled depositional patterns of sediment that accumulated adjacent to the rising salt masses. The superb exposures in La Popa Basin provide an excellent, accessible outcrop analog with which to test and calibrate salt-tectonic models derived from scaled laboratory and computer models or high-resolution seismic and well log studies of subsurface salt bodies ubiquitous in the Gulf of Mexico and other areas of petroleum exploration such as the Caspian Sea and offshore West Africa.

Strata interpreted as diapiric growth deposits flanking the diapirs display depositional thinning toward the diapir, abrupt lateral facies changes, and intense local deformation. Growth strata deformed by uplift of the rising evaporite masses were subsequently locally truncated by erosion associated with diapiric flaring or the movement of salt glaciers that repeatedly advanced and retreated over the seafloor surface. Advancement of the glaciers provided a mechanism of deforming and completely overturning underlying strata. Retreat of the glaciers corresponded to formation of erosional (locally angular) unconformities overlain by conglomeratic debris derived from failure of sediment mantling the salt glaciers. Repetition of this process resulted in the formation of progressive unconformities and growth strata analogous to those described in the proximal portions of fold and thrust terranes. However, this distinctive growth stratal geometry and unconformity bounded repetition of facies is primarily the result of halokinetic processes forming "halokinetic sequences." Periods of salt flaring and glacier development apparently correspond to periods of slow sedimentation during regional maximum flooding events.

Two types of salt bodies are recognized in La Popa Basin, small scale (<2 km diameter) salt stocks with subcircular cross sections and large scale (>10 km long) arcuate salt walls. One of the largest salt bodes, referred to as La Popa structure, displays an evolution from salt wall diapiric rise to late-stage salt evacuation and formation of a counter-regional salt weld. Sediment dispersal patterns adjacent to this structure show drainage patterns roughly paralleling the structure and sediment ponding in the axis of withdrawal basins formed adjacent to the structure.

End_of_Record - Last_Page 13---------------