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Geologic map of the Caetano caldera, Lander and Eureka counties, Nevada

Nevada Bureau of Mines and Geology Map 174

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Abstract

The Eocene (34 Ma) Caetano caldera in north-central Nevada offers an exceptional opportunity to study the physical and petrogenetic evolution of a large (20 km by 10–18 km pre-extensional dimensions) silicic magma chamber, from precursor magmatism to caldera collapse and intrusion of resurgent plutons. Caldera-related rocks shown on this map include two units of crystal-rich intracaldera tuff totaling over 4 km thickness, caldera collapse breccias, tuff dikes that fed the eruption, hydrothermally altered post-eruption rocks, and two generations of resurgent granitic intrusions (John et al., 2008). The map also depicts middle Miocene (about 16–12 Ma) normal faults and synextensional basins that accommodated >100 percent extension and tilted the caldera into a series of ~40° east-dipping blocks, producing exceptional 3-D exposures of the caldera interior (Colgan et al., 2008).


This 1:75,000-scale map is a compilation of published maps and extensive new mapping by the authors (fig. 1), and supersedes a preliminary 1:100,000-scale map published by Colgan et al. (2008) and John et al. (2008). New mapping focused on the margins of the Caetano caldera, the distribution and lithology of rocks within the caldera, and on the Miocene normal faults and sedimentary basins that record Neogene extensional faulting. The definition of geologic units and their distribution within the caldera is based entirely on new mapping, except in the northern Toiyabe Range, where mapping by Gilluly and Gates (1965) was modified with new field observations. The distribution of pre-Cenozoic rocks outside the caldera was largely compiled from existing sources with minor modifications, with the exception of the northeastern caldera margin (west of the Cortez Hills Mine), which was remapped in the course of this work and published as a stand-alone 1:6000-scale map (Moore and Henry, 2010).

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
Other Government Series
Title:
Geologic map of the Caetano caldera, Lander and Eureka counties, Nevada
Series title:
Nevada Bureau of Mines and Geology Map
Series number:
174
Volume
Map no. 174
Year Published:
2011
Language:
English
Publisher:
Nevada Bureau of Mines and Geology
Description:
Text: 10 p.; Plate: 36.0 x 28.0 inches
Number of Pages:
10
Country:
United States
State:
Nevada
County:
Eureka County;Lander County
Other Geospatial:
Caetano Caldera
Datum:
North American Datum 1983
Projection:
Universal Transverse Mercator projection
Scale:
75000
Additional Online Files(Y/N):
Y