Petrography and geochemistry of dolomites in the lower Cretaceous Edwards Formation, Taylor County, Texas

Date

2001-05

Journal Title

Journal ISSN

Volume Title

Publisher

Texas Tech University

Abstract

The Lower Cretaceous (Edwards) Mulberry Canyon Section is located in Taylor County, Texas and consists of two tidal flat-capped parasequences that contain three stages of dolomite. Of the three stages of dolomite present, previous work has established the probable environment and conditions for the formation of the first stage of dolomite, however, the environment and conditions for the other two stages has not been conclusively established. The first stage is fine-grained (<10}am), matrix-selective, oftenlaminated dolomite that has replaced the micrite in unfossiliferous mudstones (tidal flats). The second stage is fine-grained (<10nm), matrix-selective dolomite that has replaced the micrite in fossiliferous subtidal wackestones/packstones. The third stage is coarsegrained (10-240}am) dolomite that is filling or partially filling fossil-moidic porosity along with equant calcite in the fossiliferous subtidal wackestones/packstones. The purpose of this study is to use petrographic (petrography, scanning electron microscopy, and x-ray diffraction) and geochemical (major element, trace element, and isotopic) analyses to: (1) establish the depositional history of the Mulberry Canyon Section, (2) document the three stages of dolomite present in the section, and (3) establish the environment and conditions of dolomitization for each stage present in the Mulberry Canyon Section.

Description

Citation