From Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
For more information, please contact the author.

AAPG Annual Convention, Calgary, Alberta, Canada, June 19–22, 2005

Deepwater Facies Architecture and Evolution of Middle and Lower Miocene Minibasins in the Onshore Salina Basin, Southeastern Mexico

William A. Ambrose, Renaud Bouroullec, Khaled Fouad, Rebecca Jones, Edgar H. Guevara, Emilio Garciacaro, Alejandro Alberto Sosa Patron, Jaime Patiño Ruiz, and Juan de Guadalupe Cárdenas López

Abstract:

Lower Neogene minibasins in the onshore part of the Salina Basin in southeastern Mexico were associated with episodic, northward salt mobilization and withdrawal. These minibasins are penetrated by few wells and are relatively unexplored. They are characterized by cyclic deposition of upper-slope turbidites and debris-flow deposits sourced from the Chiapas Fold Belt to the south.

Middle Miocene sandy slope-channel facies in the Ogarrio area are 10- to 15-m, upward-fining successions of porous, fine- to medium-grained, crossbedded and plane-bedded sandstone with subangular clay clasts and poorly sorted organic fragments at the base. These channel deposits are flanked by thin (<5-cm scale), rippled and laminated, low-porosity, very fine grained sandstones interbedded with burrowed siltstone.

The sparsely drilled lower Miocene minibasin fill is interpreted to contain numerous intrabasin unconformities that underlie dim-amplitude, 70- to 120-m, chaotic seismic facies. These chaotic zones are interpreted to be muddy debris-flow and slump deposits, similar in seismic character and geometry to those of Pliocene strata in the Auger minibasin in offshore Louisiana. These lower Miocene chaotic zones are overlain by relatively thin, bright-amplitude, single-cycle zones, typically 20 to 40 m thick. These bright-amplitude zones, extremely continuous, are interpreted to represent potentially sandy turbidite lobe and sheet deposits. The overall minibasin fill is relatively dim amplitude updip to the south, whereas bright amplitudes are more common downdip northward, indicating a muddy bypass slope system grading into sandier, ponded turbidite facies into the basin.