Bio- and lithostratigraphy of the transitional interval of the Cherry Canyon and Bell Canyon Formations (Guadalupian, Middle Permian), southwestern Delaware Mountains, West Texas
Johnathon L. Bogacz¹, Michael J. Sweatt², and Merlynd K. Nestell³
¹Department of Earth and Environmental Sciences, The University of Texas at Arlington, Arlington, TX 76019 [email protected]
²XTO Energy, 810 Houston St., Fort Worth, TX 76102 [email protected]
³Department of Earth and Environmental Sciences, The University of Texas at Arlington, Arlington, TX 76019 [email protected]
A continuous, well exposed 162 m stratigraphic section of the upper part of the Cherry Canyon Formation and lower part of the overlying Bell Canyon Formation was measured and described from the southwestern tip of the Delaware Mountains in Culberson County 40 km northeast (approximately 31.36N, 104.60W) of Van Horn. The section is composed of beds of siltstone, very fine sandstone, and limestone. Siltstone and sandstone are usually fossil poor and have carbonate cement, but also have rare lag deposits comprised of mostly fusulinids of the genus Parafusulina. The limestone beds range from fine grained mudstone/wackestone to coarse conglomerate (thick debris flows) with clasts containing radiolarians, foraminifers, crinoids, bryozoans, rugose corals, sponges, and brachiopods. Three distinct debris flows can be mapped along the local ridges in the general area of the section; in order of oldest to youngest: the FR bed, C-debris, and B-debris. The FR bed is a fusulinid (Parafusulina) rich wackestone to packstone that varies laterally up to a few meters thick and is located roughly 40 m from the base of the measured section. The C-debris is located about 75 m from the base of the section and is variable in thickness up to 7 m thick. The megaconglomerate B-debris near the top of the section is 3.5 m thick but varies laterally in the area up to 10 m thick and can be traced more or less continuously to a well-known section of upper Hegler and lower Pinery limestone age equivalent strata exposed in a road cut about 50 km on TX FM 2185 northeast of Van Horn. Beds directly below the B-debris contain the fusulinid Polydiexodina, which is also found in the Hegler, Pinery, Radar, and McCombs limestone members of the Bell Canyon Formation in the Guadalupe Mountains region. The significance of this section is that it represents an age equivalent continuous section of the upper part of the Cherry Canyon Formation into the lower part of the Bell Canyon Formation in the southern part of the Delaware basin that can be correlated to strata present in the Guadalupe Mountains area. The purpose of the study of this section and other sections in the southernmost Delaware Mountains area is to define the bio- and lithostratigraphic nature of the contact between the Cherry Canyon and the Bell Canyon Formations.
AAPG Search and Discovery Article #90164©2013 AAPG Southwest Section Meeting, Fredericksburg, Texas, April 6-10, 2013