M. Lefticariu

Northern Illinois University, Department of Geology and Environmental Geosciences, DeKalb, IL

ABSTRACT: Diagenetic Processes in the Impact Breccia and Tertiary Sedimentary Carbonates of Northwestern Yucatan Peninsula, Mexico

Northwestern Yucatan Peninsula, Mexico is a very gently sloping carbonate platform underlain by porous and permeable limestones and dolostones. It possesses an aquifer system characterized by the presence of a freshwater lens with a significant throughput underlain by an extensive seawater intrusion. The northwestern part of the peninsula also contains the Chicxulub Impact Crater, which acted as a subsiding sedimentary basin during most of the Cenozoic Era. The surface expression of this crater created by a Late Maastrichtian major bolide impact is the Ring of Cenotes, which may represent a karstified ring. The cenote ring and Ticul Fault are the main fluid-driving structures of northwestern Yucatan (Perry et al., 1995a; Hildebrand et al., 1995; Connors et al., 1996; Perry and Velazquez- Oliman, 1996; Pope et al.,

1996; Shatrpon, 1997 Socki and; Sanchez, 1999; Kinsland et al., 2000).

Extensive data on stable isotope and major ion in groundwater as well as biostratigraphic data are available. The present paper presents a few results of the mineralogic and stable isotope studies done on core samples from inside the cenote ring-defined crater outside the crater (UNAM 5, 6, 7, 8 and Cenotillo wells) and zones close the crater to rim (UNAM 2 and Huhi wells) . All the things mentioned above make northwestern Yucatan Peninsula to be an ideal place to study low temperature diagenetic processes, the dolomite problem and structural control exerted on sedimentation and diagenesis by an impact crater.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado