Copper deposition by fluid cooling in intrusion-centered systems: New insights from the Bingham porphyry ore deposit, Utah

Abstract

Research Article| March 01, 2004 Copper deposition by fluid cooling in intrusion-centered systems: New insights from the Bingham porphyry ore deposit, Utah P.B. Redmond; P.B. Redmond 1 Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA Search for other works by this author on: GSW Google Scholar M.T. Einaudi; M.T. Einaudi 1 Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA Search for other works by this author on: GSW Google Scholar E.E. Inan; E.E. Inan 1 Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA Search for other works by this author on: GSW Google Scholar M.R. Landtwing; M.R. Landtwing 2 Isotope Geology and Mineral Resources, Department of Earth Sciences, ETH Zürich, Switzerland Search for other works by this author on: GSW Google Scholar C.A. Heinrich C.A. Heinrich 2 Isotope Geology and Mineral Resources, Department of Earth Sciences, ETH Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Author and Article Information P.B. Redmond 1 Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA M.T. Einaudi 1 Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA E.E. Inan 1 Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA M.R. Landtwing 2 Isotope Geology and Mineral Resources, Department of Earth Sciences, ETH Zürich, Switzerland C.A. Heinrich 2 Isotope Geology and Mineral Resources, Department of Earth Sciences, ETH Zürich, Switzerland Publisher: Geological Society of America Received: 02 Jul 2003 Revision Received: 01 Nov 2003 Accepted: 12 Nov 2003 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2004) 32 (3): 217–220. https://doi.org/10.1130/G19986.1 Article history Received: 02 Jul 2003 Revision Received: 01 Nov 2003 Accepted: 12 Nov 2003 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation P.B. Redmond, M.T. Einaudi, E.E. Inan, M.R. Landtwing, C.A. Heinrich; Copper deposition by fluid cooling in intrusion-centered systems: New insights from the Bingham porphyry ore deposit, Utah. Geology 2004;; 32 (3): 217–220. doi: https://doi.org/10.1130/G19986.1 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 SocietyGeology Search Advanced Search Abstract Quartz veins in porphyry copper deposits record the physiochemical evolution of fluids in subvolcanic magmatic-hydrothermal systems. We have combined cathodoluminescence (CL) petrography with fluid-inclusion microthermometry to unravel the growth history of individual quartz veins and to link this history to copper ore formation at Bingham, Utah. Early barren quartz veins with K-feldspar + biotite (potassic) alteration selvages occur throughout the 2 km vertical exposure of quartz monzonite porphyry stock. At depths of 500 m to at least 1350 m below the orebody, fluid inclusions in these barren veins trapped a single-phase CO2-bearing fluid containing ∼2–12 wt% NaClequiv. Within and to depths of 500 m below the orebody, early quartz veins contain abundant hypersaline liquid (38–50 wt% NaClequiv) and vapor-rich inclusions trapped together at temperatures of 560–350 °C and pressures of 550–140 bar, consistent with fluctuations between lithostatic and hydrostatic pressure at paleodepths of 1.4 to 2.1 km. CL petrography shows that bornite and chalcopyrite were deposited together with a later generation of quartz and K-feldspar in microscopic fractures and dissolution vugs in early barren quartz veins and wall rock. This late quartz contains hypersaline liquid (36–46 wt% NaClequiv) and vapor-rich inclusions trapped at 380–330 °C and at 160–120 bar hydrostatic pressure. We conclude that a single-phase magmatic-hydrothermal fluid underwent phase separation to hypersaline liquid (or brine) and vapor ∼500 m below the base of the orebody at a paleodepth of ∼2.5 km. Brine and vapor continued to ascend and formed multiple generations of barren quartz veins with potassic selvages. Thermal decline to temperatures below 400 °C was the main driving force for copper-iron sulfide deposition, given the lack of evidence of mixing of brines with low-salinity waters, the lack of correspondence of the ore zone with the initiation of phase separation, and no change in wall-rock alteration style. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.