Tectonic Controls on Distribution of Antler Foreland Clastic Sediments, East-Central Nevada

James H. Trexler, Jr., Steven P. Nitchman

The Devonian-Mississippian Antler foreland sediments of east-central Nevada (Chainman and Diamond Peak Formations) comprise at least three sequences, each reflecting different distribution mechanisms, and each deformed and eroded before the next was deposited: (1) the Diamond Range sequence was deposited on a submarine fan, which prograded to shallow marine and deltaic conditions, (2) the transgressive Newark Valley sequence was deposited in braided fluvial to nearshore marine conditions, and (3) the transgressive Green Springs sequence was deposited on an intertidal to subtidal marine shelf. The sequence boundaries are expressed as low-angle unconformities.

The Diamond Range sequence is interpreted as the earliest foreland basin fill, derived from the Antler highland to the west, and distal to the (now missing) Antler molasse. The sequence includes the Chainman Shale and most of the Diamond Peak Formation west of Newark Valley.

The Newark Valley and Green Springs sequences document foreland deformation and eastward thrust migration. The Newark Valley sequence represents a fluvial to shallow-marine orogenic-axis redistribution of Diamond Ranges sediments, and comprises the lower Diamond Peak Formation east of the Diamond Range.

The Green Springs sequence overlies the Newark Valley sequence and forms a relatively thin veneer of sediments cannibalized from the older sequences and in places shed westward from a low relief source approximately 50 km east of the original foreland. The Green Springs sequence was deposited during the waning stages of orogenic uplift, and comprises the upper Diamond Peak Formation and in part the lower Ely Limestone.

AAPG Search and Discovery Article #91024©1989 AAPG Pacific Section, May 10-12, 1989, Palm Springs, California.