Stratigraphy and Depositional History of Thousand Pockets Tongue of Page Sandstone and Crystal Creek Member of Carmel Formation (Middle Jurassic), Southwestern Utah: ABSTRACT

Abstract

Between the East Kaibab monocline and Zion National Park in southwestern Utah, gray, cliff-forming, cross-bedded quartz sandstone of the Thousand Pockets Tongue of the Page Sandstone grades northwestward into red, slope-forming, flat-bedded quartz sandstone of the Crystal Creek Member of the Carmel Formation. On the basis of stratigraphic position, both members are considered Bathonian in age. Coastal deposits of the Thousand Pockets Tongue prograded northwestward and interfingered with contemporaneous submarine deposits of the Crystal Creek Member along a northeast-southwest trending shoreline of the Middle Jurassic seaway. The Thousand Pockets Tongue is divided into three parts characterized by distinct sedimentary features and paleoenvironments. The gray lower part contains cross-bedded eolian sandstones (cross-bedded sandstone facies) which grade into evenly laminated and cross-bedded beach sandstones (Round Valley Draw facies). The red middle part is characterized by flat laminations, echinodern fragments, and a distribution which suggest a lagoon/tidal-flat environment. In the gray upper part, cross-bedded sandstones of eolian origin (Paria Canyon facies) grade into evenly laminated and cross-bedded beach sandstones (yellow sandstone ledge facies) and locally enclose red, flat-bedded units deposited in a washover channel-wind-tidal flat complex (red lenticular sandstone facies). The Crystal Creek Me ber is typified by evenly laminated, massive, and cross-bedded units and a lateral facies relation which suggest a lower beach and subtidal environment where storm and tidal currents dominated. Cross-stratification measurements from eolian facies in lower and upper Thousand Pockets Tongue indicate north-northeasterly winds during Bathonian time. The marginal-marine and submarine interpretation of the red beds in the Thousand Pockets Tongue and Crystal Creek Member, respectively, lends support to a diagenetic origin for the red color of these beds. End_of_Article - Last_Page 556------------