Environmental Interpretation of Lithofacies and Biofacies, Lower Sierra Madre Limestone, West Central Chiapas, Mexico

Diana K. T. Hansen

The Jiquipilas section of the Cretaceous Sierra Madre Limestone, which encompasses the lower part of the formation, was measured northwest of the town of Ocozocuautla in west-central Chiapas, Mexico. The section is 2,140 m thick and is characterized by six lithofacies interpreted to represent supratidal, intertidal platform, restricted inner shelf, open inner shelf, shoal, and open-marine middle shelf environments. Overall, the sequence is submergent, with minor emergent episodes.

Based upon cluster analysis, three biofacies associations were established: offshore middle shelf, nearshore middle shelf, and inner shelf. The lower 2,045 m of the section are dominated by the inner shelf association, while the upper 95 m are dominated by the offshore association. The nearshore middle-shelf association is a minor component throughout the section.

Correlation with a measured section from a previous study resulted in a composite thickness for the Sierra Madre Limestone in west-central Chiapas of 3,355 m. This figure is considerably greater than previously reported thicknesses for the formation. It indicates that sedimentation on the Yucatan carbonate platform during the middle Cretaceous may have approached sediment accumulation rates in modern sedimentary basins.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.