GEOLEX

Summary of Citation: Gilbert

Publication:
Ferguson, H.G., Muller, S.W. and Cathcart, S.H., 1953, Geology
   of the Coaldale quadrangle, Nevada: U.S. Geological Survey
   Geologic Quadrangle Map, GQ-23, 1 sheet, scale 1:125,000

Usage in Publication:
Gilbert andesite*

Modifications:	Geologic Province:	Dominant Lithology:
Named	Great Basin province	Andesite Basalt Volcaniclastics

Summary:
Type locality designated as exposures in southern part of Gilbert district, Monte Cristo Range [Esmeralda Co] southwestern NV. Consists of flows and agglomerates, dominantly andesitic but also containing basalt which cover crest of Monte Cristo Range. Contains typically dark porphyritic lava, few flows of hornblende andesite, hypersthene and olivine basalt, and locally sandstone, conglomerate and fanglomerate between flows. Is between 500 and 1000 ft thick. Unconformably overlies rhyolite. Age is Pliocene.

Summary of Citation: Gilbert

Publication:
Ferguson, H.G. and Cathcart, S.H., 1954, Geology of the Round
   Mountain quadrangle, Nevada: U.S. Geological Survey Geologic
   Quadrangle Map, GQ-40, 1 sheet, scale 1:125,000

Usage in Publication:
Gilbert andesite*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits Age modified	Great Basin province

Summary:
Small outcrops mapped in valley of Peavine Creek, Toiyabe Range, Round Mountain 30' quad, NV. Described as andesitic flows unconformable on and intrusive into Esmeralda formation. Unconformably underlies Toyabe [Toiyabe] quartz latite (new). Age given as Pliocene.

Summary of Citation: Gilbert

Publication:
Ferguson, H.G., Muller, S.W. and Cathcart, S.H., 1954, Geology
   of the Mina quadrangle, Nevada: U.S. Geological Survey Geologic
   Quadrangle Map, GQ-45, 1 sheet, scale 1:125,000

Usage in Publication:
Gilbert andesite*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits	Great Basin province

Summary:
Mapped in Mina 30' quad, Mineral Co, NV. Described as andesite flows grading to basalt, with much andesitic breccia and agglomerate. Correlated with Gilbert andesite of Coaldale quad on basis of lithology and relation to underlying rhyolite where present. Age given as Pliocene(?).

Summary of Citation: Gilbert

Publication:
Silberman, M.L., Bonham, H.F., Jr., Garside, L.J. and Osborne,
   D.H., 1975, New K-Ar ages of volcanic and plutonic rocks and
   ore deposits in western Nevada: Isochron/West, no. 13, p.
   13-21

Usage in Publication:
Gilbert Andesite*

Modifications:	Geologic Province:	Dominant Lithology:
Isotopic dating Age modified	Great Basin province

Summary:
K-Ar ages on sample of Gilbert Andesite (porphyritic biotite-pyroxene andesite) collected at sec.9 T3N R38E, 37 deg 07' 58"N, 117 deg 42' 29"W, Esmeralda Co, NV, yielded 15.1 +/-0.5 Ma on biotite and 13.6 +/-0.4 Ma on plagioclase. Age is at least in part middle Miocene based on time scale of Berggren (1972).

Summary of Citation: Gilbert

Publication:
Kleinhampl, F.J. and Ziony, J.I., 1985, Geology of northern Nye
   County, Nevada: Nevada Bureau of Mines and Geology Bulletin,
   no. 99A, 172 p., (incl. geologic map, scale 1:250,000)

Usage in Publication:
Gilbert Andesite*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits	Great Basin province

Summary:
Gilbert Andesite as used by Ferguson and Cathcart (1954) in southern Toiyabe Range is mapped with andesitic rocks on map of northern Nye Co, NV. However unit here "is probably much older than and unrelated to the type Gilbert Andesite." Occurs as dikes and flows and a possible vent complex in southern Toiyabe Range. Also shown on map in southern Monitor Range.

Summary of Citation: Gilbert

Publication:
Shawe, D.R., 1987, Stratigraphic nomenclature of volcanic rocks
   near Manhattan, southern Toquima Range, Nye County, Nevada,
   IN Stratigraphic notes, 1985-86: U.S. Geological Survey
   Bulletin, 1775-A, p. A1-A8

Usage in Publication:
Gilbert Andesite*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits Isotopic dating	Great Basin province

Summary:
Gilbert Andesite geographically restricted from Manhattan district in southern Toquima Range. Rocks previously mapped as such are now designated the Crone Gulch Andesite (new). Rocks in the Manhattan area are from different volcanic source and are older (latest Oligocene or earliest Miocene; K-Ar (plagioclase) and fission-track (apatite) age of about 22 Ma, Shawe and others, in press). Gilbert Andesite is middle Miocene (15.1 +/-0.6 Ma K-Ar age).