156 Structural Geology (Posters) II: Deformation Processes

LATE PALEOZOIC FOLDING AND THRUST FAULTING IN THE NORTHERN HOT CREEK RANGE, NYE COUNTY, NEVADA

Paper number: 156-19
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

The northern Hot Creek Range in central Nevada exposes Paleozoic rocks that have been deformed by at least two contractional events. Our mapping, structural analysis, and biostratigraphic dating of Paleozoic rocks have revealed: (1) new information concerning the style, order and timing of the contraction, (2) definitive pre-Early Triassic contraction, and (3) a previously undescribed mid-Mississippian limestone.

Two thrust faults, one east-directed and the other northwest-directed, place older Paleozoic rocks over Pennsylvanian rocks. Superposed mesoscopic folds indicate that east-directed thrusting was the earliest deformation event. F1 folds are related to the east-directed thrust; it places an Ordovician-Mississippian thrust plate over an unnamed Pennsylvanian limestone. F2 folds are related to a northwest-directed thrust that places Devonian Nevada Group over the same Pennsylvanian limestone. Low-angle extensional faults and high-angle normal faults complicate these map relationships.

The Ordovician-Mississippian thrust plate is unconformably overlain by an Early Triassic (Griesbachian) sandstone that also overlies the Pennsylvanian rocks of the footwall. This relationship requires pre-Early Triassic emplacement of the Ordovician-Mississippian thrust plate. The hinterland-directed thrust plate also appears to be unconformably overlain by the same Early Triassic sandstone, but critical contact relations are obscured by cover.

The existence of a mid-Mississippian (Osagean-Meramecian) limestone is unusual in this region. Rocks of that age in Nevada are usually siliciclastic or else they are nonexistent (i.e., represented by an unconformity). Mid-Mississippian deformation has been recently recognized throughout much of central Nevada.

A similar deformation history, consisting of foreland-vergent followed by hinterland-vergent folding and thrusting has been documented on the Nevada Test Site which lies ~200 km south of the northern Hot Creek Range.