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Chemostratigraphy of the Pennsylvanian-Permian Section in the Midland Basin of West Texas with Focus on the Wolfcamp Formation: Developing a Stronger Mudrock Correlation and Paleo-depositional Understanding

Cortez, Milton *1
(1) Geology, University of Texas at Arlington, Bedford, TX.

The purpose of this research is to develop a chemostratigraphy dataset for West Texas Midland Basin drill cores that preserve the late Pennsylvanian to early Permian strata. Interpretation of the dataset will help to refine well-to-well correlation and to better understand well-log results, and the spatial variability in depositional environments around the basin. Furthermore, chemostratigraphic data may also prove valuable for assessing post-depositional signatures that may vary across the basin. Ultimately, it is anticipated that a well-defined chemostratigraphy will be developed from Atokan-age clastics up through the lower Permian-age Upper Spraberry Formation.

Preliminary handheld energy-dispersive x-ray fluorescence (HH-ED-XRF) results will be shown from the Atoka, Strawn, Pennsylvanian, Dean, and Spraberry Formations. The following elements have been analyzed: Mg, Al, S, Si, P, K, Ti, Ca, Mn, Fe. Trace metal results will also be shown. Powder samples for a sub-set of intervals were analyzed for TIC and TOC, as well as stable carbon and nitrogen isotopes of organic matter. Samples taken from sandstone beds were not analyzed due to low concentrations of carbon and lack of a calibration for the XRF. Thin sections will be taken at numerous intervals in order to observe petrographic characteristics of mudrocks having high TOC values. A comparison of geochemical and well-log data will be presented. The ultimate goal of this research is to correlate sedimentary stratigraphic trends and assumptions to chemostratigraphic findings in order to refine our overall knowledge of the Midland Basin.


AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California