Title: Geologic map of the Soldier Peak quadrangle, Elko County, Nevada
Author: Arthur W. Snoke, Keith A. Howard, and Seth Dee
Year: 2022
Series: Map 191
Version:
Format: 1 sheet: 31 x 35 inches, cross sections, color; text: 31 pages, color
Scale: 1:24,000
The Soldier Peak quadrangle exposes evidence of a complex structural and metamorphic history involving a long stratigraphic record that ranges from the Neoproterozoic to the Holocene. The quadrangle exposes major elements of the architecture of the Ruby Mountains metamorphic core complex in the northern Ruby Mountains and East Humboldt Range. Mapped stratigraphic units ranging from Neoproterozoic to Upper Devonian are metamorphosed to amphibolite facies and intruded by myriad granitic to gabbroic bodies of Cretaceous to Oligocene age. The metamorphosed stratigraphic units trace out large recumbent folds in the infrastructure of the complex. An Oligocene to Miocene mylonitic shear zone, hundreds of meters thick, overprints the upper part of the complex. The Ruby Mountains–East Humboldt detachment-fault zone in turn is superposed on the mylonitic shear zone. The detachment-fault zone includes fault slices of the upper part of the stratigraphic sequence (Ordovician to Devonian), metamorphosed to greenschist facies and commonly brittlely faulted. A plexus of higher low-angle-fault slices of unmetamorphosed Upper Devonian to Permian formations defines the upper plate of the detachment fault and forms the upper tier of the core complex.
Pleistocene glacial moraine deposits are present in the mountains, and alluvial-fan and glacial-outwash deposits occur in Lamoille Valley west of the mountains. Vitric fallout ash originally correlated to the 2.1-Ma Huckleberry Ridge Tuff in the Yellowstone Plateau volcanic field occurs low in the exposed alluvial basin sequence. A new 40Ar/39Ar date on sanidine yielded an age of 2.35±0.07 Ma, somewhat older than the Huckleberry Ridge Tuff. Normal faults bounding the west side of the Ruby Mountains show offset as young as late Pleistocene and project toward seismically imaged subsurface listric faults.
This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G20AC00390, 2020.
Suggested citation:
Snoke, A.W., Howard, K.A., and Dee, S., 2022, Geologic map of the Soldier Peak quadrangle, Elko County, Nevada: Nevada Bureau of Mines and Geology Map 191, scale 1:24,000, 31 p.
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