The Li isotope response to mountain uplift

Abstract

Research Article| January 01, 2015 The Li isotope response to mountain uplift Philip A.E. Pogge von Strandmann; Philip A.E. Pogge von Strandmann 1Institute of Earth and Planetary Sciences, University College London and Birkbeck College, University of London, Gower Street, London WC1E 6BT, UK Search for other works by this author on: GSW Google Scholar Gideon M. Henderson Gideon M. Henderson 2Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK Search for other works by this author on: GSW Google Scholar Author and Article Information Philip A.E. Pogge von Strandmann 1Institute of Earth and Planetary Sciences, University College London and Birkbeck College, University of London, Gower Street, London WC1E 6BT, UK Gideon M. Henderson 2Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK Publisher: Geological Society of America Received: 08 Aug 2014 Revision Received: 23 Oct 2014 Accepted: 29 Oct 2014 First Online: 09 Mar 2017 Online Issn: 1943-2682 Print Issn: 0091-7613 © 2014 Geological Society of America Geology (2015) 43 (1): 67–70. https://doi.org/10.1130/G36162.1 Article history Received: 08 Aug 2014 Revision Received: 23 Oct 2014 Accepted: 29 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 Philip A.E. Pogge von Strandmann, Gideon M. Henderson; The Li isotope response to mountain uplift. Geology 2015;; 43 (1): 67–70. doi: https://doi.org/10.1130/G36162.1 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 Silicate weathering is a key process by which CO2 is removed from the atmosphere. It has been proposed that mountain uplift caused an increase in silicate weathering, and led to the long-term Cenozoic cooling trend, although this hypothesis remains controversial. Lithium isotopes are tracers of silicate weathering processes, and may allow this hypothesis to be tested. Recent studies have demonstrated that the Li isotope ratio in seawater increased during the period of Himalayan uplift (starting ca. 45 Ma), but the relationship between uplift and the Li isotope ratio of river waters has not been tested. Here we examine Li isotope ratios in rivers draining catchments with variable uplift rates from South Island, New Zealand. A negative trend between δ7Li and uplift shows that areas of rapid uplift have low δ7Li, whereas flatter floodplain areas have high δ7Li. Combined with U activity ratios, the data suggest that primary silicates are transported to floodplains, where δ7Li and (234U/238U) are driven to high values due to preferential uptake of 6Li by secondary minerals and long fluid-mineral contact times that enrich waters in 234U. In contrast, in mountainous areas, fresh primary mineral surfaces are continuously provided, driving δ7Li and (234U/238U) low. This trend is opposite to that expected if the increase in Cenozoic δ7Li in the oceans is driven directly by mountain uplift. These data suggest that the increase in seawater δ7Li reflects the formation of floodplains and the increased formation of secondary minerals, rather than weathering of mountain belts. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.