REEQUILIBRATION PROCESSES IN MAGNETITE FROM IRON SKARN DEPOSITS

Abstract

Research Article| January 01, 2015 REEQUILIBRATION PROCESSES IN MAGNETITE FROM IRON SKARN DEPOSITS* Hao Hu; Hao Hu 1State Key Laboratory of Geological Processes and Mineral Resources, and Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar David Lentz; David Lentz 2Department of Earth Sciences, University of New Brunswick, Fredericton, NB E3B 5A3, Canada Search for other works by this author on: GSW Google Scholar Jian-Wei Li; Jian-Wei Li † 1State Key Laboratory of Geological Processes and Mineral Resources, and Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China †Corresponding author: e-mail, jwli@cug.edu.cn Search for other works by this author on: GSW Google Scholar Travis McCarron; Travis McCarron 2Department of Earth Sciences, University of New Brunswick, Fredericton, NB E3B 5A3, Canada Search for other works by this author on: GSW Google Scholar Xing-Fu Zhao; Xing-Fu Zhao 1State Key Laboratory of Geological Processes and Mineral Resources, and Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Douglas Hall Douglas Hall 3Microscopy and Microanalytical Facilities, University of New Brunswick, Fredericton, NB E3B 5A3, Canada Search for other works by this author on: GSW Google Scholar Economic Geology (2015) 110 (1): 1–8. https://doi.org/10.2113/econgeo.110.1.1 Article history received: 07 Aug 2014 accepted: 06 Oct 2014 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Hao Hu, David Lentz, Jian-Wei Li, Travis McCarron, Xing-Fu Zhao, Douglas Hall; REEQUILIBRATION PROCESSES IN MAGNETITE FROM IRON SKARN DEPOSITS. Economic Geology 2015;; 110 (1): 1–8. doi: https://doi.org/10.2113/econgeo.110.1.1 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 SocietyEconomic Geology Search Advanced Search Abstract Textural and compositional data for magnetite from nine iron skarn deposits in Canada, Romania, and China show that most samples have reequilibrated by dissolution and reprecipitation, oxy-exsolution, and/or recrystallization. The dissolution and reprecipitation processes are most extensive and are present in most magnetite samples examined, whereas the oxy-exsolution occurs only in high-Ti magnetite, forming exsolution lamellae of Fe-Ti-Al oxides. Electron microprobe analysis indicates that the reequilibration processes have significantly modified the minor and trace element compositions of magnetite, notably Si, Mg, Ca, Al, Mn, and Ti, whereas oxy-exsolution is effective in decreasing the Ti content of high-Ti magnetite. Many analyses of magnetite grains from the skarn deposits plot variably in the banded iron formations (BIF), iron oxide–copper-gold (IOCG), or porphyry Cu fields using the Ti + V versus Ca + Al + Mn discrimination diagram. This pattern suggests that trace element data for magnetite that has unusual composition and/or reequilibrated cannot be reliably used as a petrogenetic indicator. Mixing of externally derived saline fluids with Fe-rich magmatic-hydrothermal solutions, an increase in temperature, and local decreasing pressure and fO2 are considered the most important causes for the dissolution and reprecipitation, or recrystallization, of the magnetite; increasing fO2 and decreasing temperature may facilitate oxy-exsolution of Fe-Ti-Al oxides in high-Ti magnetite. Results presented here highlight the importance of detailed textural characterization prior to in situ chemical analysis of magnetite grains so that mineral compositions can be properly evaluated in terms of the genesis and evolution of iron skarn deposits. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.