Amy L. Weislogel¹, Timothy F. Lawton¹
(1) Institute of Tectonic Studies, New Mexico State University, Las Cruces, NM

Abstract: Salt diapir influence on local sedimentation patterns, Maastrichtian Muerto Formation, northeastern Mexico

Evolution of El Gordo evaporite diapir locally controlled the depositional systems, lithofacies relationships and sequence stratigraphy of the Maastrichtian Muerto Formation in La Popa basin. Sedimentation patterns of the Muerto Formation adjacent to the diapir were influenced by local subsidence driven by salt withdrawal and local bathymetric shallowing due to diapiric rise. The Muerto Formation represents the first, coarse synorogenic foredeep deposits of 5.4km of basin-fill strata in the Sierra Madrean foreland basin system. Throughout the foreland, this thick succession (~600m) of marine and deltaic strata forms part of an eastward progradational system which in the vicinity of El Gordo diapir conformably overlies deep water mudstone of the Parras Shale and is conformably overlain by the Porterillos Formation.

Three lithofacies assemblages form upward-coarsening progradational parasequences, which exhibit dramatic lateral shallowing and thinning toward the diapir. A diapir-proximal lithofacies assemblage is composed of primarily high-energy shoreface, foreshore and tidal lithofacies, with a minimum thickness of 67m. An intermediate lithofacies assemblage includes ~275m of subordinate offshore and prodelta to deltaic distributary bar lithofacies, and dominant shoreface, restricted marine, and tidal channel complex lithofacies. The intermediate lithofacies assemblage contains the greatest abundance of sandy, bioclastic coral-, gastropod- and oyster-bearing carbonate deposits. A diapir-distal lithofacies assemblage consists of ~350m primarily offshore, shoreface, and restricted marine lithofacies with a subordinate tidal-channel complex lithofacies.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana