Geology and Hydrostratigraphy of Guadalupe River State Park and Honey Creek State Natural Area, Kendall and Comal Counties, Texas

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Publication Date

January 2014

Abstract

Hydrogeologic mapping and descriptions of the lithostratigraphy and hydrostratigraphy of Guadalupe River State Park and Honey Creek State Natural Area, Kendall and Comal Counties, Texas, are presented in this first detailed 1:24,000 geologic map, along with proposed names and descriptions of the hydrostratigraphic units in the study area. Variations in the amount and type of porosity of the lithostratigraphic unit, which vary depending on the depositional environment, lithology, structural history and diagenesis support the resulting hydrostratigraphy proposed herein. Rocks exposed in the study area consist of Early Cretaceous sedimentary rocks that are assigned to the Trinity Group. The lithostratigraphy includes the Hammett Shale, Cow Creek Limestone, Hensell Sand Members of the Pearsall Formation, and the lower member of the Glen Rose Limestone. These lithologic units contain shale, grainstone, sandstone, and fossiliferous limestone, alternating and interfingering with mudstone, wackestone, packstone, and grainstone. The Trinity aquifer hydrostratigraphic units shown on the map and described herein are characterized by their porosity types. Porosity types were first determined from an analysis of two boreholes conducted in comparison with 143 geophysical logs from northern Bexar County, Texas. The cores and geophysical log comparison resulted in division of the lower member of the Glen Rose Limestone into six hydrostratigraphic units, designated A through F. Of those six units, only three remain in the study area because of erosion. The proposed naming of these three hydrostratigraphic units is based on topographic or historical features that occur in the outcrop area of those units. Hydrostratigraphic units that correlate with the boundaries of the formation have been given formational names excluding the lithologic modifier. The Doeppenschmidt hydrostratigraphic unit is stratigraphically the highest interval in the study area, characterized by interparticle, moldic, burrowed, bedding plane, fracture, and cav

Keywords

Hydrogeologic, Trinity Group, Hydrostratigraphy

Document Type

Article

Notes

Vol. 3303 (2014-01-01).

Identifier

SFS0073549_00001

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