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100 Ma timing paradox of Archean gold, Abitibi greenstone belt (Canada): New evidence from U-Pb and Pb-Pb evaporation ages of hydrothermal zircons

1994; Geological Society of America; Volume: 22; Issue: 12 Linguagem: Inglês

10.1130/0091-7613(1994)022 2.3.co;2

1943-2682

Robert Kerrich, T. Kurtis Kyser,

Geomagnetism and Paleomagnetism Studies

Research Article| December 01, 1994 100 Ma timing paradox of Archean gold, Abitibi greenstone belt (Canada): New evidence from U-Pb and Pb-Pb evaporation ages of hydrothermal zircons Robert Kerrich; Robert Kerrich 1Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 0W0, Canada Search for other works by this author on: GSW Google Scholar T. Kurtis Kyser T. Kurtis Kyser 1Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 0W0, Canada Search for other works by this author on: GSW Google Scholar Geology (1994) 22 (12): 1131–1134. https://doi.org/10.1130/0091-7613(1994)022 2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Robert Kerrich, T. Kurtis Kyser; 100 Ma timing paradox of Archean gold, Abitibi greenstone belt (Canada): New evidence from U-Pb and Pb-Pb evaporation ages of hydrothermal zircons. Geology 1994;; 22 (12): 1131–1134. doi: https://doi.org/10.1130/0091-7613(1994)022 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 SocietyGeology Search Advanced Search Abstract Abundant hydrothermal zircon occurs within quartz-tourma-line veins at four gold deposits in the Val d"Or district of the Archean Abitibi greenstone belt, Canada. Host rocks to the gold-bearing veins are characterized by pronounced metasomatic enrichment of Zr, Hf, Y, and rare earth elements. Hydrothermal zircons contain inclusions of quartz, tourmaline, scheelite, pyrite, and gold. In hydrothermal zircons and quartz, primary low-salinity H2-CO2, fluid inclusions coexist with CO2-rich inclusions, indicating CO2, unmixing and gold precipitation at 260 to 380 °C and ∼2 kbar. The zircons have 207Pb/206Pb evaporation ages of 2683 ±20 to 2703 ±4 Ma, close to a concordant U-Pb age of 2693 ±2 Ma, both commensurate with previous SHRIMP ages for the zircons. The same vein systems have U-Pb ages on rutile and titanite, Sm-Nd dates on scheelite, and 40Ar/39Ar ages on muscovite that scatter between 2630 to 2579 Ma; these ages gave rise to a "late gold" model.In the Archean Superior province, vein gold deposits are related in space and time to terrane boundary structures which mark the diachronous accretion of allochthonous tectonostratigraphic terranes from south to north from 2720 to 2680 Ma. Consequently, the vein zircon ages of ∼2690 to 2680 Ma at Val d"Or represent the primary mineralizing event, consistent with its late kinematic timing throughout the Superior Province and with Late Archean supercontinent assembly globally, whereas the young scattered ages record the time of secondary fluid events associated with reactivation of the structures, resetting some isotopic systems below their conventional blocking temperature. 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.