Fluvial and Deltaic Facies and Environments of the Late Permian Back-Reef Shelves of the Permian Basin of Texas and New Mexico

Abstract

The Artesia Group is a sequence of carbonates, evaporites, and clastics that was deposited across the back-reef shelves of the Permian Basin during late Permian time. There has been some controversy over the depositional environments of the clastic members of the Artesia Group and the role of sea level fluctuations in their accumulation. However, the results of a regional core study of the Queen Formation of the Artesia Group indicate that they were largely deposited in desert fluvial and deltaic environments during low-stands of sea level. Three fluvial-deltaic facies are recognized within the clastic members of the Queen. The first consists of medium to very find sandstones and silty sandstones with cross-beds, ripple cross-laminae, and planar and wavy laminae. This facies forms wavy sheets that thicken and thin along linear trends, and was deposited in sandy braided streams. The second facies consists of very find to fine sandstones, silty sandstones, and siltstones with ripple cross-laminae, planar and wavy laminae, cross-beds, clay drapes and pedogenetic cutans, as well as siltstones and silty mudstones with haloturbation structures and evaporite nodules. This facies forms thick planar sheets, and was deposited in fluvial sandflats and adjacent fluvial-dominated continental sabkhas. The third facies consists ofmore » cyclic deposits of haloturbated silty mudstones that grade into siltstones and very fine sandstones with crossbeds, planar and wavy laminae, haloturbation structures and evaporite nodules. Each cycle forms a lobate body that is bounded by carbonates or evaporites and which was deposited in sheet deltas that formed along the landward margins of a back-reef lagoon.« less