Abstract

The Anacacho Formation is an Upper Cretaceous carbonate bank sequence in southwest Texas. The bank sequence and associated lithofacies formed in marine waters located between the waning Cretaceous Seaway to the north and the Gulf of Mexico to the south. In southwest Texas, the Anacacho grew as patchy biostromes on igneous intrusive bathymetric highs or as atoll reef and bank deposits formed on and around seamounts on the Austin sea floor. The igneous activity that created a substratum for skeletal growth occured in the Late Cretaceous during the earliest stages of the Laramide Orogeny.

In a study area located in Kinney and Uvalde Counties, southwest Texas, patchy bank formation took place over an igneous bathymetric high. Skeletal debris shed from the bank facies in Uvalde County was reworked and transported to the southwest in the form of migrating sand waves. These sand waves may have been driven by surface currents generated by dominant northerly wind patterns. As skeletal debris accumulated vertically into the photic zone, a new bank sequence began to form in Kinney County.