Significance of weathering Himalayan metasedimentary rocks and leucogranites for the Sr isotope evolution of seawater during the early Miocene

Research Article| September 01, 1995 Significance of weathering Himalayan metasedimentary rocks and leucogranites for the Sr isotope evolution of seawater during the early Miocene Nigel Harris Nigel Harris 1Department of Earth Sciences, Open University, Milton Keynes MK7 6AA, United Kingdom Search for other works by this author on: GSW Google Scholar Author and Article Information Nigel Harris 1Department of Earth Sciences, Open University, Milton Keynes MK7 6AA, United Kingdom Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1995) 23 (9): 795–798. https://doi.org/10.1130/0091-7613(1995)023<0795:SOWHMR>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Nigel Harris; Significance of weathering Himalayan metasedimentary rocks and leucogranites for the Sr isotope evolution of seawater during the early Miocene. Geology 1995;; 23 (9): 795–798. doi: https://doi.org/10.1130/0091-7613(1995)023<0795:SOWHMR>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 Changes in 87Sr/86Sr ratios of seawater may reflect varying rates of chemical weathering or variations in the isotopic compositions of continental rocks undergoing weathering. The unusually high dissolved Sr concentrations and 87Sr/86Sr ratios that characterize the Ganges and Brahmaputra-Tsangpo river systems are a consequence of weathering Early Proterozoic age metasedimentary rocks and anatectic Miocene granites exposed on the southern slopes of the Himalayas. On average, the metasedimentary rocks are characterized by abundances of 87Sr about twice those of the derived granites. The rapid rise in 87Sr/86Sr ratios of seawater during the early Miocene was virtually coincident with metamorphism and anatexis of Himalayan metasedimentary rocks. Model calculations indicate that 50%–75% of the overall change in 87Sr/86Sr ratios for seawater between 20 and 15 Ma could have resulted from exposure of Himalayan metasedimentary rocks to chemical weathering. Rapid, tectonically controlled exhumation of the metasedimentary rocks is required to expose these lithologies by 20–18 Ma, to generate the increase in the 87Sr flux of the trans-Himalayan rivers during the early Miocene. 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.