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Episodic caldera volcanism in the Miocene southwestern Nevada volcanic field: Revised stratigraphic framework, 40Ar/39Ar geochronology, and implications for magmatism and extension

1994; Geological Society of America; Volume: 106; Issue: 10 Linguagem: Inglês

10.1130/0016-7606(1994)106 2.3.co;2

1943-2674

David A. Sawyer, Robert J. Fleck, Marvin A. Lanphere, R. Warren, D.E. Broxton, Mark R. Hudson,

Evolution and Paleontology Studies

Research Article| October 01, 1994 Episodic caldera volcanism in the Miocene southwestern Nevada volcanic field: Revised stratigraphic framework, 40Ar/39Ar geochronology, and implications for magmatism and extension DAVID A. SAWYER; DAVID A. SAWYER 1U.S. Geological Survey, M.S. 913, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar R. J. FLECK; R. J. FLECK 2U.S. Geological Survey, M.S. 937, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar M. A. LANPHERE; M. A. LANPHERE 2U.S. Geological Survey, M.S. 937, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar R. G. WARREN; R. G. WARREN 3EES-1, M.S. D462, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Search for other works by this author on: GSW Google Scholar D. E. BROXTON; D. E. BROXTON 3EES-1, M.S. D462, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Search for other works by this author on: GSW Google Scholar MARK R. HUDSON MARK R. HUDSON 1U.S. Geological Survey, M.S. 913, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar Author and Article Information DAVID A. SAWYER 1U.S. Geological Survey, M.S. 913, Denver, Colorado 80225 R. J. FLECK 2U.S. Geological Survey, M.S. 937, 345 Middlefield Road, Menlo Park, California 94025 M. A. LANPHERE 2U.S. Geological Survey, M.S. 937, 345 Middlefield Road, Menlo Park, California 94025 R. G. WARREN 3EES-1, M.S. D462, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 D. E. BROXTON 3EES-1, M.S. D462, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 MARK R. HUDSON 1U.S. Geological Survey, M.S. 913, Denver, Colorado 80225 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1994) 106 (10): 1304–1318. https://doi.org/10.1130/0016-7606(1994)106 2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation DAVID A. SAWYER, R. J. FLECK, M. A. LANPHERE, R. G. WARREN, D. E. BROXTON, MARK R. HUDSON; Episodic caldera volcanism in the Miocene southwestern Nevada volcanic field: Revised stratigraphic framework, 40Ar/39Ar geochronology, and implications for magmatism and extension. GSA Bulletin 1994;; 106 (10): 1304–1318. doi: https://doi.org/10.1130/0016-7606(1994)106 2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The middle Miocene southwestern Nevada volcanic field (SWNVF) is a classic example of a silicic multicaldera volcanic field in the Great Basin. More than six major calderas formed between >15 and 7.5 Ma. The central SWNVF caldera cluster consists of the overlapping Silent Canyon caldera complex, the Claim Canyon caldera, and the Timber Mountain caldera complex, active from 14 to 11.5 Ma and centered on topographic Timber Mountain. Locations of calderas older than the Claim Canyon caldera source of the Tiva Canyon Tuff are uncertain except where verified by drilling. Younger peralkaline calderas (Black Mountain and Stonewall Mountain) formed northwest of the central SWNVF caldera cluster. We summarize major revisions of the SWNVF stratigraphy that provide for correlation of lava flows and small-volume tuffs with the widespread outflow sheets of the SWNVF.New laser fusion 40Ar/39Ar isotopic ages are used to refine and revise the timing of eruptive activity in the SWNVF. The use of high-sensitivity mass spectrometry allowed analysis of submilligram-sized samples with analytical uncertainties of ∼0.3% (1σ), permitting resolution of age differences as small as 0.07 Ma. These results confirm the revised stratigraphic succession and document a pattern of episodic volcanism in the SWNVF. Major caldera episodes (Belted Range, Crater Flat, Paintbrush, Timber Mountain, and Thirsty Canyon Groups) erupted widespread ash-flow sheets within 100-300 k.y. time spans, and pre- and post-caldera lavas erupted within 100-300 k.y. of the associated ash flows. Peak volcanism in the SWNVF occurred during eruption of the Paintbrush and Timber Mountain Groups, when over 4500 km3 of metaluminous magma was erupted in two episodes within 1.35 m.y., separated by a 750 k.y. magmatic gap. Peralkaline and metaluminous magmatism in the SWNVF overlapped in time and space. The peralkaline Tub Spring and Grouse Canyon Tuffs erupted early, and the peralkaline Thirsty Canyon Group tuffs and Stonewall Flat Tuff erupted late in the history of the SWNVF, flanking the central, volumetrically dominant peak of metaluminous volcanism. Magma chemistry transitional between peralkaline and metaluminous magmas is indicated by petrographic and chemical data, particularly in the overlapping Grouse Canyon and Area 20 calderas of the Silent Canyon caldera complex.Volcanism in the SWNVF coincided with the Miocene peak of extensional deformation in adjoining parts of the Great Basin. Although regional extension was concurrent with volcanism, it was at a minimum in the central area of the SWNVF, where synvolcanic faulting was dominated by intra-caldera deformation. Significant stratal tilting and paleomagnetically determined dextral shear affected the southwestern margin of the SWNVF between the Paint-brush and Timber Mountain caldera episodes. Larger magnitude detachment faulting in the Bullfrog Hills, southwest of the central SWNVF caldera cluster, followed the climactic Timber Mountain caldera episode. Postvolcanic normal faulting was substantial to the north, east, and south of the central SWNVF caldera cluster, but the central area of peak volcanic activity remained relatively unextended in postvolcanic time. Volcanism and extension in the SWNVF area were broadly concurrent, but SWNVF area were broadly concurrent, but in detail they were episodic in time and not coincident in space First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.