Origin of Silt in the Permian Phosphoria Formation

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

ABSTRACT Origin of Siltstone Facies in the Permian Phosphoria Formation Alan Carroll EAR-0106898 Silty marine mudrocks represent one of the most volumetrically important sedimentary rock types, but their genesis remains very poorly understood. The proposed study will investigate siltstone facies contained within the Permian Phosphoria Formation in the western U.S. A regional sedimentologic and stratigraphic investigation will be conducted to assess the importance of suspension settling versus other depositional processes, and to examine the relationship of siltstone and other facies to changing sea level. Oxygen isotopic analyses of different quartz grain size fractions will be used to constrain their temperature of crystallization and thus their origin (reworked versus primary quartz). Finally, grain size distributions from siltstone and other silty facies will be measured at a number of widely distributed sites. These measurements, combined with high-resolution stratigraphic studies, will be used to examine grainsize trends across the Phosphoria sea.