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Abstract: Preliminary Evaluation of Antler Orogenic Effects in the Snake Mountains, Northeastern Nevada

Michael J. McFarlane

The Roberts fountains allochthon (RMA) in the Snake Mountains is typical of the RMA in other regions of Nevada in age and lithology of rock units. It is emplaced over an autochthon comparable to that typically beneath the RMA in other areas, though more diverse in formations and structural complexity.

Stratigraphic and structural units of the RMA in the Snake Mountains are of typical deep marine "western facies" RMA lithologies of Ordovician, Silurian, and Devonian age, with Mississippian (probably Kinderhookian) foreland basin units of sandy turbidites within mudstones present near the base. Overlying the allochthon is a widespread basal conglomerate upon an erosional surface. The conglomerate is possibly late Pennsylvanian (with age under evaluation), and clearly postdates thrust faulting and associated deformation within the RMA. The age of pre-Mesozoic thrust faulting and erosion manifested in this range must be Mississippian to middle Pennsylvanian in age.

Folds in the RMA indicate two populations of thrust motion, one from the northwest, one from the north. These directions are more commonly from the north than is typical in other locations of the RMA. The allochthon contains foreland-dipping duplexes. The autochthon has been deformed more than is typical in other regions of Nevada. The Eureka Quartzite has been thrust faulted within the autochthon, and occurs in large-scale folds. Duplexing may be present in the autochthon, and account for the autochthon in present topographic highs.

AAPG Search and Discovery Article #90959©1995 AAPG Rocky Mountain Section Meeting, Reno, Nevada