Abstract

The Queen Formation is a complex sequence of carbonates, evaporites, and clastics that was deposited on the back-reef shelves of the Permian Basin during late Permian time. A seven year study of cores of the Queen clastic members shows that they were largely deposited in desert fluvial and deltaic depositional environments during low stands of sea level. This study summarizes the facies characteristics of these depositional environments.

Three fluvial-deltaic facies can be distinguished for the clastic members of the Queen. The first is composed of light to dark gray, fine to very-fine grained sandstones and silty sandstones with cross-beds, ripple cross-laminae, and planar and wavy laminae. This facies forms thin wavy sheets that thicken and thin along linear dip-oriented trends and was deposited in the channels and cross-channel bars of sandy braided streams. The second facies is composed of reddish-brown, very fine to fine-grained sandstones, silty sandstones and siltstones with ripple cross-laminae, planar and wavy laminae, cross-beds, clay drapes, and pedogenetic cutans; as well as some reddish-brown siltstones and silty mudstones with haloturbation structures and evaporite nodules. This facies forms thick sheets and was deposited in poorly channelized fluvial sandflats and adjacent fluvial-dominated continental sabkhas. The third facies is composed of cyclic deposits of poorly stratified and haloturbated silty mudstones that grade into siltstones, silty sandstones, and very fine-grained sandstones characterized by cross-beds, planar and wavy laminae, haloturbation structures, and evaporite nodules. Each cycle forms a thick lobate body that is bounded above and below by thick-bedded evaporites. These cycles were deposited in poorly channelized sheet deltas that gradually filled back-reef lagoon areas.