Cyclostratigraphy and Sequence Stratigraphy of the Lower Cretaceous Cupido Formation, Northeastern Mexico

Maya Elrick

The Lower Cretaceous (Barremian-Aptian) Cupido Formation of northeastern Mexico represents the southern extension of a major, rimmed carbonate platform that bordered the Gulf of Mexico during lower-middle Cretaceous time. The Cupido Formation (Sligo Formation equivalent in the U.S.) forms a major progradational package (700-900 m thick) of basinal mudstone, shelf-margin talus, shelf-margin biostromes, back-margin pack/grainstone, lagoonal wackestone, and peritidal facies. Stratigraphic sections measured along the platform interior and back-margin region are composed of meter-scale, upward-shallowing cycles (or parasequences). Platform interior facies contain peritidal and subtidal cycles; peritidal cycles are characterized by bioturbated pelletal-skeletal packstone or pel id-skeletal pack/grainstone (shallow subtidal facies) overlain by thick to thin laminites (intertidal/supratidal facies) which may be capped by solution breccias. Common subtidal cycles are composed of thin, nodular-bedded, pellet-skeletal packstone overlain by coarse peloid-skeletal pack/grainstone. Bank-margin cycles are typically composed of coarse peloid grainstone-dominated peritidal and subtidal cycles and are interbedded with weak to noncyclic peloid grainstone intervals.

Large-scale transgressive-regressive facies trends, cycle stacking patterns (changes in cycle thickness and predominance of cycle subfacies), and subaerial exposure features define up to seven depositional sequences and their internal systems tracts. Both conformable (type 2) and unconformable (type 1) sequence boundaries/zones are recognized on the basis of cycle stacking patterns and significant subaerial exposure features, respectively.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995