Carbonate Cycles: Lower Pennsylvanian Marble Falls Formation, Mason and Kimble Counties, Texas: ABSTRACT

Abstract

Samples from detailed measured sections were successfully classified by using Folk's descriptive limestone classification. Later in the investigation genetic rock categories (facies) that reflect ecologic environments were recognized and classified separately. The nine facies are shown in the following table. Table A transgressive facies tract can be identified, comprising four depositional areas: (1) nearshore and tidal flat, bearing the mottled facies; (2) middle shelf composed either totally of the churned dark fragmental facies or of Ivanovia banks with the churned dark fragmental facies to landward and the light fragmental facies to seaward; (3) shelf edge with algal banks or knolls, the tubular alga facies in deeper or protected areas, the Komia facies in turbulent or shallow areas; (4) seaward slope bearing the laminated dark fragmental facies grading seaward to the shale facies. The regressive facies tract begins with the seaward migration of the mottled facies and the lateral expansion of the Komia facies. It culminates on the shelf with the mottled facies and Chaetetes facies which developed on a surface of bypassing, and on the slope by deposition of debris transported from the Komia facies. Cycles have four phases: (1) minor transgression with shale at the base overlain by a poorly developed regressive facies tract; (2) slight regression with a poorly developed regressive facies tract; (3) major transgression with well developed transgressive facies tract; (4) major regression with well developed regressive facies tract. End_of_Article - Last_Page 376------------