Unusually Cu-rich magmas associated with giant porphyry copper deposits: Evidence from Bingham, Utah

Abstract

Research Article| January 01, 2006 Unusually Cu-rich magmas associated with giant porphyry copper deposits: Evidence from Bingham, Utah Daniel P. Core; Daniel P. Core 1 Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48019, USA Search for other works by this author on: GSW Google Scholar Stephen E. Kesler; Stephen E. Kesler 1 Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48019, USA Search for other works by this author on: GSW Google Scholar Eric J. Essene Eric J. Essene 1 Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48019, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Daniel P. Core 1 Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48019, USA Stephen E. Kesler 1 Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48019, USA Eric J. Essene 1 Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48019, USA Publisher: Geological Society of America Received: 23 Apr 2005 Revision Received: 08 Sep 2005 Accepted: 18 Sep 2005 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2006) 34 (1): 41–44. https://doi.org/10.1130/G21813.1 Article history Received: 23 Apr 2005 Revision Received: 08 Sep 2005 Accepted: 18 Sep 2005 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Daniel P. Core, Stephen E. Kesler, Eric J. Essene; Unusually Cu-rich magmas associated with giant porphyry copper deposits: Evidence from Bingham, Utah. Geology 2006;; 34 (1): 41–44. doi: https://doi.org/10.1130/G21813.1 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 Mass-balance constraints indicate that formation of giant porphyry copper deposits (PCDs) requires either highly efficient collection of Cu from large volumes of magma or unusually Cu-rich parent magmas. Support for the second of these possibilities has been discovered in the form of mafic enclaves with abundant bornite and chalcopyrite in the Last Chance stock, one of the parent intrusions of the giant Bingham PCD, Utah, United States. Mineral assemblages and compositions indicate that the Last Chance enclaves are autoliths consisting of phases that crystallized from the intrusion, and that the intrusion was unusually enriched in Cu. One possible mechanism for generating Cu-rich magmas is fractional crystallization during pyrrhotite undersaturated conditions. The high fO2 conditions observed for the Last Chance stock may have allowed such an evolution. Alternatively, if the magma has not undergone significant fractionation, early crystallization of chalcopyrite and bornite from the magma would indicate that the lower-crustal source region for the magma probably contained Cu-Fe sulfides. Possible Cu-rich source regions are a subcrustal mafic intrusion with sulfide cumulates, or a deeply buried metamorphic terrane containing Cu deposits such as those in the Curaca Valley (Brazil) or Okiep (South Africa). Heterogeneous distribution of Cu-Fe sulfides in an Okiep-type source terrane would produce local PCDs such as Bingham, or large accumulations of Cu-Fe sulfides, possibly in the form of cumulates in subcrustal intrusions at convergent margins, could produce giant PCD provinces such as those in Indonesia, Papua New Guinea, and central Chile. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.