Sodic-Calcic Family of Alteration in Porphyry Systems of Arizona and Adjacent New Mexico

Research Article| June 01, 2019 Sodic-Calcic Family of Alteration in Porphyry Systems of Arizona and Adjacent New Mexico Simone E. Runyon; Simone E. Runyon 1Department of Geology and Geophysics, University of Wyoming, 1000 E. University Ave., Laramie, Wyoming 82071-2000, USA2Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, D.C., 20015, USA3Lowell Institute for Mineral Resources, Department of Geosciences, University of Arizona, 1040 East Fourth St., Tucson, Arizona 85721-0077, USA †Corresponding author: e-mail, srunyon@uwyo.edu Search for other works by this author on: GSW Google Scholar Phillip A. Nickerson; Phillip A. Nickerson 3Lowell Institute for Mineral Resources, Department of Geosciences, University of Arizona, 1040 East Fourth St., Tucson, Arizona 85721-0077, USA *Present address: Bronco Creek Exploration, Inc., 1815 E. Winsett Street, Tucson, Arizona 85719-6547. Search for other works by this author on: GSW Google Scholar Eric Seedorff; Eric Seedorff 3Lowell Institute for Mineral Resources, Department of Geosciences, University of Arizona, 1040 East Fourth St., Tucson, Arizona 85721-0077, USA Search for other works by this author on: GSW Google Scholar Mark D. Barton; Mark D. Barton 3Lowell Institute for Mineral Resources, Department of Geosciences, University of Arizona, 1040 East Fourth St., Tucson, Arizona 85721-0077, USA Search for other works by this author on: GSW Google Scholar Frank K. Mazdab; Frank K. Mazdab 3Lowell Institute for Mineral Resources, Department of Geosciences, University of Arizona, 1040 East Fourth St., Tucson, Arizona 85721-0077, USA Search for other works by this author on: GSW Google Scholar Pilar Lecumberri-Sánchez; Pilar Lecumberri-Sánchez 4Department of Earth and Atmospheric Science, University of Alberta, Edmonton, Alberta T6G 2E3, Canada Search for other works by this author on: GSW Google Scholar Matthew Steele-MacInnis Matthew Steele-MacInnis 4Department of Earth and Atmospheric Science, University of Alberta, Edmonton, Alberta T6G 2E3, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Simone E. Runyon 1Department of Geology and Geophysics, University of Wyoming, 1000 E. University Ave., Laramie, Wyoming 82071-2000, USA2Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, D.C., 20015, USA3Lowell Institute for Mineral Resources, Department of Geosciences, University of Arizona, 1040 East Fourth St., Tucson, Arizona 85721-0077, USA Phillip A. Nickerson 3Lowell Institute for Mineral Resources, Department of Geosciences, University of Arizona, 1040 East Fourth St., Tucson, Arizona 85721-0077, USA Eric Seedorff 3Lowell Institute for Mineral Resources, Department of Geosciences, University of Arizona, 1040 East Fourth St., Tucson, Arizona 85721-0077, USA Mark D. Barton 3Lowell Institute for Mineral Resources, Department of Geosciences, University of Arizona, 1040 East Fourth St., Tucson, Arizona 85721-0077, USA Frank K. Mazdab 3Lowell Institute for Mineral Resources, Department of Geosciences, University of Arizona, 1040 East Fourth St., Tucson, Arizona 85721-0077, USA Pilar Lecumberri-Sánchez 4Department of Earth and Atmospheric Science, University of Alberta, Edmonton, Alberta T6G 2E3, Canada Matthew Steele-MacInnis 4Department of Earth and Atmospheric Science, University of Alberta, Edmonton, Alberta T6G 2E3, Canada †Corresponding author: e-mail, srunyon@uwyo.edu *Present address: Bronco Creek Exploration, Inc., 1815 E. Winsett Street, Tucson, Arizona 85719-6547. Publisher: Society of Economic Geologists Accepted: 25 Mar 2019 First Online: 24 Jun 2019 Online Issn: 1554-0774 Print Issn: 0361-0128 © 2019 Economic GeologyEconomic Geology Economic Geology (2019) 114 (4): 745–770. https://doi.org/10.5382/econgeo.4661 Article history Accepted: 25 Mar 2019 First Online: 24 Jun 2019 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Simone E. Runyon, Phillip A. Nickerson, Eric Seedorff, Mark D. Barton, Frank K. Mazdab, Pilar Lecumberri-Sánchez, Matthew Steele-MacInnis; Sodic-Calcic Family of Alteration in Porphyry Systems of Arizona and Adjacent New Mexico. Economic Geology 2019;; 114 (4): 745–770. doi: https://doi.org/10.5382/econgeo.4661 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 SocietyEconomic Geology Search Advanced Search Abstract Sodic-calcic alteration has affected numerous districts with Laramide porphyry systems across Arizona and New Mexico. Previously undocumented Na-Ca alteration has been identified at Charleston, Sycamore Canyon, Silver Bell, and the Ninetysix Hills in Arizona and the Central mining district in New Mexico. These new occurrences are compared to sodic-calcic alteration at the Sierrita-Esperanza deposit (Pima district), the Ajo mining district, the Tea Cup pluton (Kelvin-Riverside district), and the Eagle Pass dike swarm in Arizona.Spatial positions, crosscutting relationships, and mineral assemblages and compositions allow for interpretation of the geochemical conditions of formation and implications for associated hydrothermal processes. Diopside- or andradite-grossular solid solution (Ad68-Ad72)–stable assemblages representative of calcic alteration typically occur in deep and/or distal positions but are less commonly exposed. The sodic-calcic and sodic alteration types, however, occur more proximally to the porphyry orebody. Sodic-calcic assemblages containing Na plagioclase (An10-An33)-Ca amphibole ± epidote are focused along granite cupolas near the base of ore-bodies, and these grade into shallower sodic assemblages containing albite (An00-An09)-epidote-chlorite. Mineral composition and fluid inclusion data suggest that Na-Ca plagioclase-bearing assemblages form at higher temperatures (360°–470°C+) than later, lower-temperature albite-epidote assemblages (>250°C). Calculated δD isotope compositions of fluids in equilibrium with Na-Ca alteration minerals span a broad range (–46 to –1‰) and are consistently less negative than magmatic fluids. Where members of the Na-Ca family of alteration assemblages are present in porphyry systems, many lines of evidence—including isotopic compositions of minerals and the geologic alteration zoning patterns—are consistent with an origin by incursion of saline external fluids.Where Na-Ca alteration is present, it is best developed at relatively deep levels of porphyry systems. Several Laramide systems that are well exposed at comparably deep levels lack Na-Ca alteration, probably because sources of saline fluid were absent or hydrologic conditions were unfavorable for the incursion of saline external fluids. Though similar in temperatures, isotopic compositions, mineral assemblages, and zoning patterns, Na-Ca alteration in Laramide systems is volumetrically smaller than in Jurassic systems documented in the western United States, probably because saline external fluids were much less abundant during the Laramide after a tectonically driven excursion in paleoclimate from arid to humid conditions. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.