ABSTRACT: Late Mississippian Episodic Sedimentation in the Antler Foreland Basin, East-Central Nevada

PERRY, ANDREW J., and JAMES H. TREXLER, JR., University of Nevada at Reno, Reno, NV

Cycle sedimentation in the upper section of the Antler foreland basin is similar in nature and age to the cyclothems of the eastern United States. The evolution of the Antler foreland basin is documented by the stratigraphy present in the Diamond Range, east-central Nevada. The Newark Valley sequence there consists of the upper part of the Ely Limestone. These strata were deposited in the Late Mississippian and Early Pennsylvanian during the waning stages of the Antler orogeny. Paleoenvironmental analysis of the lower Newark Valley sequence suggests alluvial and marine carbonate sedimentation in a semi-arid paleoclimate. Environmentally diagnostic features include red beds with developed calcrete horizons, mud cracks, and preserved channel and overbank relationships. The dominantly si iciclastic lower part of the Newark Valley sequence records three transgressive intervals beginning in the middle Chesterian and continuing to the Morrowan. Each interval involves an established alluvial setting shifting to a predominantly carbonate setting. The final interval includes the pronounced transition from siliciclastic deposition to carbonate deposition at the Mississippian-Pennsylvanian boundary. These sedimentary cycles can be attributed to several causes including: channel avulsion and lobe switching, climatic changes, sporadic

tectonic activity, and eustatic sea level changes, or the combinations of these factors. Overall, the cyclic sedimentary record from the Late Mississippian Antler foreland setting suggests possible similarities with other cyclical sequences of similar age.

AAPG Search and Discovery Article #91016©1992 AAPG-SEPM-SEG-EMD Pacific Section Meeting, Sacramento, California, April 27-May 1, 1992 (2009)