Delta Front-Delta Plain Fades of the Pennsylvanian Haymond Formation, Northeastern Marathon Basin, Texas

Abstract

The sandstone beds of the middle and upper parts of the Haymond Formation cropping out on the Allison Ranch, Marathon Basin, west Texas, are divisible into several genetic categories based mainly on the external morphology, arrangement and boundary relations with adjoining rocks, nature of bedding, fossil, and quartz content. The two major genetic types are sheet sands of the delta front and multiple braided distributary channel sands of the overlying delta plain facies. That the delta front was subjected to higher physical energy than the delta plain is suggested by the relatively high quartz content which increases in the more seaward facies. The stratigraphic position of these delta front and delta plain sandstones of the middle and upper Haymond overlying the prodelta sediments of the lower Haymond reflects deltaic progradation in the Marathon area during Middle Pennsylvanian time.