Xenolithic evidence for Proterozoic crustal evolution beneath the Colorado Plateau

Research Article| April 01, 1999 Xenolithic evidence for Proterozoic crustal evolution beneath the Colorado Plateau Jane Selverstone; Jane Selverstone 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131-1116 Search for other works by this author on: GSW Google Scholar Aurora Pun; Aurora Pun 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131-1116 Search for other works by this author on: GSW Google Scholar Kent C. Condie Kent C. Condie 2Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801 Search for other works by this author on: GSW Google Scholar Author and Article Information Jane Selverstone 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131-1116 Aurora Pun 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131-1116 Kent C. Condie 2Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1999) 111 (4): 590–606. https://doi.org/10.1130/0016-7606(1999)111<0590:XEFPCE>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 MailTo Tools Icon Tools Get Permissions Search Site Citation Jane Selverstone, Aurora Pun, Kent C. Condie; Xenolithic evidence for Proterozoic crustal evolution beneath the Colorado Plateau. GSA Bulletin 1999;; 111 (4): 590–606. doi: https://doi.org/10.1130/0016-7606(1999)111<0590:XEFPCE>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 Tertiary diatremes of the Navajo volcanic field brought a wide variety of Proterozoic xenoliths to the surface of the Colorado Plateau. Examination of crustal xenoliths from the Navajo volcanic field diatremes permits reconstruction of Proterozoic pressure-temperature (P-T) histories beneath the Colorado Plateau. Diatremes from the northwest part of the Navajo volcanic field carry the greatest variety of xenoliths, including metasedimentary rocks, amphibolites, felsic gneisses, mafic granulites, and crustally derived eclogites; these rock types show variable degrees of hydrous alteration and evidence for complex reaction histories. In contrast, diatremes from the southeast part of the Navajo volcanic field contain primarily mafic and felsic granulites that show fewer reaction textures and less alteration; metasedimentary and eclogitic xenoliths are absent in these diatremes. The P-T paths from the northwest xenoliths are counterclockwise and reach temperatures as high as 850 °C and pressures equal to or greater than 10 kbar. Later hydrous alteration occurred around 500 °C and 8–12 kbar. Xenoliths from the southeast diatremes preserve little evidence of their P-T evolution, but paths involve heating and/or decompression. The differing rock types, P-T paths, and alteration histories of the northwest and southeast populations suggest that Proterozoic tectonism juxtaposed two distinct crustal blocks beneath the Colorado Plateau. Previous workers have postulated that the boundary between the Proterozoic Yavapai and Mazatzal provinces occurs in the region; our data support the existence of a northeast-trending boundary beneath the Four Corners area. If the eclogitic metamorphism and hydrous alteration are Proterozoic in age, their restricted occurrence beneath the northwest part of the plateau suggests that subduction was northwest dipping during Proterozoic accretion of the Mazatzal province onto North America. This content is PDF only. Please click on the PDF icon to access. 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.