Interdune Pond Carbonates, Weber Sandstone (Pennsylvanian-Permian), Northern Utah and Colorado

Abstract

ABSTRACT The eolian Pennsylvanian-Permian Weber Sandstone, predominantly a 300-m-thick, cross-bedded quartz arenite, contains carbonate lenses deposited in interdune ponds. The carbonates are thin (< 60 cm), laterally impersistent (100-1,000 m), and consist chiefly of unfossiliferous, fenestral dolomitic mudstone. An interdune pond origin is supported by a) lenticular, three-dimensional geometry, b) exclusive occurrence along first-order bounding surfaces. c) lateral intertonguing with dry and damp interdune sandstone facies, d) lack of marine fossils, and e) megascopic features indicative of extremely shallow to emergent, hypersaline to brackish conditions (e.g., desiccation and sheet cracks, fenestral fabrics and/or burrow/root tubes, pseudomorphs after anhydrite nodules, algal mat or str matolitic, wrinkled laminations). Weber interdune ponds were probably fed by spring seeps and ground waters derived from deeper aquifers, analogous in some respects to present-day oasis ponds in the Saharan erg of North Africa. Interdune pond carbonates represent a relatively uncommon end member in a broad spectrum of interdune facies.