Geochronology of Cenozoic rocks in the Bodie Hills, California and Nevada
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- Document: Report (4.5 MB pdf)
- Appendix 1 (709 kB xlsx) Analytical results of CO2-laser-fusion and resistance-furnace incremental heating 40Ar/39Ar age determinations for samples of the Bodie Hills volcanic field.
- Appendix 3 (26 kB xlsx) Analytical results of CO2-laser incremental heating 40Ar/39Ar experiments (Denver lab, Cosca) for samples of the Bodie Hills volcanic field.
- Appendix 2 (101 kB xlsx) Analytical results of furnace incremental heating 40Ar/39Ar experiments (Denver lab, Snee) for samples of the Bodie Hills volcanic field.
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The purpose of this report is to present geochronologic data for unaltered volcanic rocks, hydrothermally altered volcanic rocks, and mineral deposits of the Miocene Bodie Hills and Pliocene to Pleistocene Aurora volcanic fields of east-central California and west-central Nevada. Most of the data presented here were derived from samples collected between 2000–13, but some of the geochronologic data, compiled from a variety of sources, pertain to samples collected during prior investigations. New data presented here (tables 1 and 2; Appendixes 1–3) were acquired in three U.S. Geological Survey (USGS) 40Ar/39Ar labs by three different geochronologists: Robert J. Fleck (Menlo Park, CA), Lawrence W. Snee (Denver, CO), and Michael A. Cosca (Denver, CO). Analytical methods and data derived from each of these labs are presented separately.
The middle to late Miocene Bodie Hills volcanic field (BHVF) is a large (>700 km2), long-lived (~9 million years [m.y.]), episodic eruptive complex (John and others, 2012) in the southern segment of the ancestral Cascades arc (du Bray and others, written commun., 2015) north of Mono Lake and east of Bridgeport, California (fig. 1). The field is near the west edge of the Walker Lane and the northwest edge of the Mina deflection where structures related to these shear zones may have localized magmatism. The Walker Lane (fig. 1) is a broad, northwest-striking zone of right-lateral shear that accommodates right-lateral motion between the Pacific and North America plates; the Mina deflection constitutes a 60-km-long right step in the Walker Lane (Faulds and Henry, 2008; Oldow, 1992, 2003; Stewart, 1988). The Bodie Hills volcanic field includes at least 31 volcanic rock units erupted from 21 significant volcanic eruptive centers.
Four trachyandesite stratovolcanoes developed along the margins of the volcanic field and numerous silicic trachyandesite to rhyolite flow dome complexes erupted more centrally. Volcanism in the Bodie Hills volcanic field peaked at two periods, ~15.0 to 12.6 million years before present (Ma) and ~9.9 to 8.0 Ma, which were dominated by emplacement of large stratovolcanoes and large silicic trachyandesite-dacite lava domes, respectively. A final period of small-volume silicic dome emplacement began in the western part of the volcanic field at ~6 Ma and culminated at ~5.5 Ma (John and others, 2012).
|Publication Subtype||USGS Numbered Series|
|Title||Geochronology of Cenozoic rocks in the Bodie Hills, California and Nevada|
|Series title||Data Series|
|Publisher||U.S. Geological Survey|
|Publisher location||Reston, VA|
|Contributing office(s)||Geology, Minerals, Energy, and Geophysics Science Center|
|Description||Report: iii, 26 p.; 3 Appendixes|
|Other Geospatial||Bodie Hills|
|Online Only (Y/N)||Y|
|Additional Online Files (Y/N)||Y|
|Google Analytic Metrics||Metrics page|