|
|
 |
|||||||||||||||||
|
|||||||||||||||||
 |
|||||||||||||||||
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
,2
1 Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82071
2 Department of Geophysical Sciences and Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637
3 Department of Geology and Geophysics, Rice University, Houston, Texas 77251
The East Humboldt Range of Nevada provides a record of deep-crustal tectonic processes in a classic Cordilleran metamorphic core complex located in the hinterland of the Late Cretaceous to early Tertiary Sevier orogenic belt. New constraints reported here on the metamorphic history of this terrane suggest an overall clockwise pressure-temperature-time (P-T-t) path that began with deep tectonic burial and metamorphism at kyanite + staurolite + garnet grade before Late Cretaceous time (possibly in Late Jurassic time?). Subsequently, higher-temperature Late Cretaceous peak metamorphism overprinted this event, resulting in widespread partial melting and leucogranite injection contemporaneous with emplacement of a large-scale recumbent fold (the Winchell Lake nappe). A new 207Pb*/206Pb* date of 84.8 ± 2.8 Ma on syntectonic leucogranite from the hinge zone of this fold constrains the age of this major phase of tectonism. Metamorphism at this time probably reached the second sillimanite isograd, at least at deep structural levels, with peak P-T conditions of 800 °C and >9 kbar. High-grade conditions persisted during extensional tectonic denudation throughout much of Tertiary time. In conjunction with previously published work, the petrologic and thermobarometric results reported here for the northern East Humboldt Range delineate a steeply decompressional P-T trend that extends from 
9 kbar and 800 °C to 5 kbar and 630 °C. In the light of decompressional reaction textures, microstructural evidence, and previously published thermochronometric results, we interpret this trend as a P-T-t path for Late Cretaceous to Oligocene time. At least 2 kbar of this decompression (equivalent to at least 7 km of denudation) occurred in Late Cretaceous to early Tertiary time. This interpretation supports the idea that tectonic exhumation of deep-crustal rocks in northeastern Nevada began during or immediately after the closing stages of the Sevier orogeny. Finally, the steepness of the proposed P-T-t path implies a thermal evolution from a colder to a much hotter geotherm, a circumstance that probably requires plastic thinning of the lower plate in addition to brittle attenuation and removal of the upper plate during Tertiary extension.
This article has been cited by other articles:
|
|
 |
|
  P. A. Camilleri Growth, behavior, and textural sector zoning of biotite porphyroblasts during regional metamorphism and the implications for interpretation of inclusion trails: Insights from the Pequop Mountains and Wood Hills, Nevada, USA Geosphere, June 1, 2009; 5(3): 215 - 251. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P.F. Rey, C. Teyssier, and D.L. Whitney Extension rates, crustal melting, and core complex dynamics Geology, May 1, 2009; 37(5): 391 - 394. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Druschke, A. D. Hanson, M. L. Wells, T. Rasbury, D. F. Stockli, and G. Gehrels Synconvergent surface-breaking normal faults of Late Cretaceous age within the Sevier hinterland, east-central Nevada Geology, May 1, 2009; 37(5): 447 - 450. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. R. Premo, P. Castineiras, and J. L. Wooden SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: Is this really Archean crust? Geosphere, December 1, 2008; 4(6): 963 - 975. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.C. Fosdick and J.P. Colgan Miocene extension in the East Range, Nevada: A two-stage history of normal faulting in the northern Basin and Range Geological Society of America Bulletin, September 1, 2008; 120(9-10): 1198 - 1213. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. L. Wells and T. D. Hoisch The role of mantle delamination in widespread Late Cretaceous extension and magmatism in the Cordilleran orogen, western United States Geological Society of America Bulletin, May 1, 2008; 120(5-6): 515 - 530. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. D. Henry Ash-flow tuffs and paleovalleys in northeastern Nevada: Implications for Eocene paleogeography and extension in the Sevier hinterland, northern Great Basin Geosphere, February 1, 2008; 4(1): 1 - 35. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. E. Jones Crafford Paleozoic tectonic domains of Nevada: An interpretive discussion to accompany the geologic map of Nevada Geosphere, February 1, 2008; 4(1): 260 - 291. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. A. Sullivan and A. W. Snoke Comparative anatomy of core-complex development in the northeastern Great Basin, U.S.A. Rocky Mountain Geology, July 1, 2007; 42(1): 1 - 29. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.P. PLATT From orogenic hinterlands to Mediterranean-style back-arc basins: a comparative analysis Journal of the Geological Society, March 1, 2007; 164(2): 297 - 311. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. R. Dickinson Geotectonic evolution of the Great Basin Geosphere, December 1, 2006; 2(7): 353 - 368. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. G. DeCelles Late Jurassic to Eocene evolution of the Cordilleran thrust belt and foreland basin system, western U.S.A. Am J Sci, February 1, 2004; 304(2): 105 - 168. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. J. Nutt, C. J. Nutt, and A. H. Hofstra Alligator Ridge District, East-Central Nevada: Carlin-Type Gold Mineralization at Shallow Depths Economic Geology, September 1, 2003; 98(6): 1225 - 1241. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. A. Howard Crustal Structure in the Elko-Carlin Region, Nevada, during Eocene Gold Mineralization: Ruby-East Humboldt Metamorphic Core Complex as a Guide to the Deep Crust Economic Geology, April 1, 2003; 98(2): 249 - 268. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S.-Y. LEE, C. G. BARNES, A. W. SNOKE, K. A. HOWARD, and C. D. FROST Petrogenesis of Mesozoic, Peraluminous Granites in the Lamoille Canyon Area, Ruby Mountains, Nevada, USA J. Petrology, April 1, 2003; 44(4): 713 - 732. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M.A. House, S.A. Bowring, and K.V. Hodges Implications of middle Eocene epizonal plutonism for the unroofing history of the Bitterroot metamorphic core complex, Idaho-Montana Geological Society of America Bulletin, April 1, 2002; 114(4): 448 - 461. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. D. Hoisch, M. L. Wells, and L. M. Hanson Pressure-temperature paths from garnet-zoning: Evidence for multiple episodes of thrust burial in the hinterland of the Sevier orogenic belt American Mineralogist, January 1, 2002; 87(1): 115 - 131. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. G. BARNES, B. R. BURTON, T. C. BURLING, J. E. WRIGHT, and H. R. KARLSSON Petrology and Geochemistry of the Late Eocene Harrison Pass Pluton, Ruby Mountains Core Complex, Northeastern Nevada J. Petrology, May 1, 2001; 42(5): 901 - 929. [Abstract] [Full Text] [PDF]
|
|
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
