Geologic framework, hydrostratigraphy, and ichnology of the Blanco, Payton, and Rough Hollow 7.5-minute quadrangles, Blanco, Comal, Hays, and Kendall Counties, Texas

Abstract

For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit http://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit http://store.usgs.gov.Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.Suggested citation: Clark, A.K., Golab, J.A., and Morris, R.R., 2016, Geologic framework, hydrostratigraphy, and ichnology of the Blanco, Payton, and Rough Hollow 7.5-minute quadrangles, Blanco, Comal, Hays, and Kendall Counties, Texas (ver. 1.1, September 20, 2016) AcknowledgmentsThis study was completed on both public and private lands, and the authors would like to extend their thanks to the landowners and managers in Blanco, Comal, Hays, and Kendall Counties who provided access to their property, which greatly improved the completeness and accuracy of this study. Geologic AbstractThis report presents the geologic framework, hydrostratigraphy, and ichnology of the Trinity and Edwards Groups in the Blanco, Payton, and Rough Hollow 7.5-minute quadrangles in Blanco, Comal, Hays, and Kendall Counties, Texas.

Bioturbation-influenced fluid pathways within a carbonate platform system: The Lower Cretaceous (Aptian–Albian) Glen Rose Limestone

“…Ichnologic assessment is important in aquifer and reservoir characterization,however, most studies have been conducted in siliciclastic units (e.g., Keswani and Pemberton, 2007;Tonkin et al, 2010;Gingras et al, 2012). Bioturbation commonly decreases porosity and permeability in both siliciclastic and carbonate aquifers that contain significant intergranular flow (e.g., Gingras et al, 2004;.Karstic aquifers such as the Edwards and Trinity Groups; however, cannot transmit significant quantities of fluid through interparticle porosityand rely on bioturbation to create porosity and lateral fluid pathways (e.g., Mathews, 1967;Gingras et al, 1999;Cunningham and Sukop, 2011;Baniak et al 2013;Golab et al, 2015).Although previous authors have conducted ichnological assessment of some carbonate hydrocarbon reservoirs (e.g., Gingras et al, 1999Gingras et al, , 2004La Croix et al, 2011;Baniak et al, 2013), thebiogenic aspect of karstic aquifers has been overlooked in the literature (Cunningham et al, 2009;Sukop, 2011, 2012;Golab et al, 2015;Clark et al, 2016). The GRL is a dual-permeability system and absent fracture and karstic porosity, ichnofossils with coarse-grained infill are the primary fluid pathways throughout most strata and are a significant factor in directing water between major faults and karstic features.…”