Isotopic studies of the late Archean plutonic rocks of the Wind River Range, Wyoming

Research Article| July 01, 1985 Isotopic studies of the late Archean plutonic rocks of the Wind River Range, Wyoming J. S. STUCKLESS; J. S. STUCKLESS 1U.S. Geological Survey, Box 25046, MS 963, Denver Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar C. E. HEDGE; C. E. HEDGE 1U.S. Geological Survey, Box 25046, MS 963, Denver Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar R. G. WORL; R. G. WORL 1U.S. Geological Survey, Box 25046, MS 963, Denver Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar K. R. SIMMONS; K. R. SIMMONS 1U.S. Geological Survey, Box 25046, MS 963, Denver Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar I. T. NKOMO; I. T. NKOMO 1U.S. Geological Survey, Box 25046, MS 963, Denver Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar D. B. WENNER D. B. WENNER 2Department of Geology, University of Georgia, Athens, Georgia 30602 Search for other works by this author on: GSW Google Scholar Author and Article Information J. S. STUCKLESS 1U.S. Geological Survey, Box 25046, MS 963, Denver Federal Center, Denver, Colorado 80225 C. E. HEDGE 1U.S. Geological Survey, Box 25046, MS 963, Denver Federal Center, Denver, Colorado 80225 R. G. WORL 1U.S. Geological Survey, Box 25046, MS 963, Denver Federal Center, Denver, Colorado 80225 K. R. SIMMONS 1U.S. Geological Survey, Box 25046, MS 963, Denver Federal Center, Denver, Colorado 80225 I. T. NKOMO 1U.S. Geological Survey, Box 25046, MS 963, Denver Federal Center, Denver, Colorado 80225 D. B. WENNER 2Department of Geology, University of Georgia, Athens, Georgia 30602 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1985) 96 (7): 850–860. https://doi.org/10.1130/0016-7606(1985)96<850:ISOTLA>2.0.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 J. S. STUCKLESS, C. E. HEDGE, R. G. WORL, K. R. SIMMONS, I. T. NKOMO, D. B. WENNER; Isotopic studies of the late Archean plutonic rocks of the Wind River Range, Wyoming. GSA Bulletin 1985;; 96 (7): 850–860. doi: https://doi.org/10.1130/0016-7606(1985)96<850:ISOTLA>2.0.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 Isotopic studies of the Rb-Sr and U-Th-Pb systems in whole-rock samples and the U-Pb systematics for zircons document the existence of two late Arehean intrusive events in the Wind River Range. All of the systems examined indicate an age of ∼2,630 ± 20 m.y. for the Louis Lake batholith. Apparent ages for the Bears Ears pluton range from 2,504 ± 40 m.y. to 2,575 ± 50 m.y. The scatter in apparent ages for the Bears Ears pluton does not appear to be primarily the result of disturbance by postintrusive events, but it may be explained by an isotopically inhomogenous magma at the time of intrusion.Data for a few samples indicate that the Wind River Range was affected locally by a postmagmatic hydrothermal event that was approximately Tertiary in age. This event lowered δ18O values and disturbed parent-daughter relationships in most of the isotopic systems investigated, but it was recent enough that there is no demonstrable effect in the Pb-Pb system.The Bears Ears pluton has some chemical and petrologic features that are similar to those reported for the granites in the Granite Mountains to the east. These granites are spatially associated with low-temperature uranium deposits of Tertiary age and have been shown to have lost large amounts of uranium during the early to middle Tertiary. U-Pb systematics indicate, however, that the low to moderate uranium contents and highly variable Th/U values noted for the Bears Ears pluton are best interpreted as being primary features. If uranium was lost after magma generation, the loss most likely occurred at the time of intrusion. Such a loss could account for uraniferous Precambrian pegmatites southwest of the main part of the Range.The two intrusive units apparently were derived from different protoliths that were formed during early to middle Archean. Initial isotopic ratios and petrochemistry for the Louis Lake batholith are consistent with an early Archean trondhjemitic to tonalitic source. The protolith for the Bears Ears pluton must have been more evolved and somewhat younger. Inconsistencies as to the degree of evolution of this protolith, as inferred from isotopic and trace-element data, suggest that the protolith may have been subjected to high-grade meta-morphism that caused loss of Rb and U prior to generation of the magma. 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.