Detecting the extent of ca. 1.1 Ga Midcontinent Rift plume heating using U-Pb thermochronology of the lower crust

Abstract

Research Article| September 11, 2018 Detecting the extent of ca. 1.1 Ga Midcontinent Rift plume heating using U-Pb thermochronology of the lower crust Graham Harper Edwards; Graham Harper Edwards 1Department of Earth and Planetary Sciences, University of California Santa Cruz, 1156 High Street, EMS A232, Santa Cruz, California 95064, USA Search for other works by this author on: GSW Google Scholar Terrence Blackburn Terrence Blackburn 1Department of Earth and Planetary Sciences, University of California Santa Cruz, 1156 High Street, EMS A232, Santa Cruz, California 95064, USA Search for other works by this author on: GSW Google Scholar Geology (2018) 46 (10): 911–914. https://doi.org/10.1130/G45150.1 Article history received: 13 May 2018 rev-recd: 06 Aug 2018 accepted: 08 Aug 2018 first online: 07 Sep 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Graham Harper Edwards, Terrence Blackburn; Detecting the extent of ca. 1.1 Ga Midcontinent Rift plume heating using U-Pb thermochronology of the lower crust. Geology 2018;; 46 (10): 911–914. doi: https://doi.org/10.1130/G45150.1 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 The occurrence of mantle plumes in the geologic past is hypothesized to be marked by voluminous basaltic volcanism and topographic and gravitational anomalies. Missing from these identifying characteristics is a direct measurement of the elevated mantle temperatures associated with an upwelling channel from the deep mantle. To assess the extent of plume heating in the 1.1 Ga Midcontinent Rift System (North America), we present U-Pb thermochronologic evidence for a ca. 1.1 Ga sublithosphere heat source near Attawapiskat, Canada, >600 km from the inferred plume center. Apatite and rutile U-Pb cooling dates from middle to lower crustal xenoliths exhumed in the Jurassic Victor kimberlite record a thermal history >2.5 b.y. in duration. Shallow amphibolite and gabbro yield Archean to Paleoproterozoic dates with high U-Pb discordance, consistent with middle crust cooling prior to 1.1 Ga. Deeper garnet-bearing samples yield younger dates with low U-Pb discordance. Replicating these data with models reveals a thermal history in which the extent of heating corresponds with sample depth, an observation consistent with heating from below. Thermochronologic data are best fit by model simulations in which the Attawapiskat lithosphere experienced a ca. 1.1 Ga heating event triggered by partial lithosphere removal and mantle temperatures >200 °C in excess of that of ambient mantle, consistent with a model of ∼100 m.y. plume head residence beneath the Attawapiskat region. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.