The strontium isotope systematics of the Orange River, Southern Africa

Research Article| December 01, 2000 The strontium isotope systematics of the Orange River, Southern Africa S. de Villiers; S. de Villiers Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ United Kingdom. e-mail: svi199@ese.cam.ac.uk Search for other works by this author on: GSW Google Scholar J.S. Compton; J.S. Compton Department of Geological Sciences, University of Cape Town, Rondebosch 7701 South Africa Search for other works by this author on: GSW Google Scholar M. Lavelle M. Lavelle Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ United Kingdom. British Antarctic Survey, Madingly Road, Cambridge CB3 OET United Kingdom. Search for other works by this author on: GSW Google Scholar Author and Article Information S. de Villiers Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ United Kingdom. e-mail: svi199@ese.cam.ac.uk J.S. Compton Department of Geological Sciences, University of Cape Town, Rondebosch 7701 South Africa M. Lavelle Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ United Kingdom. British Antarctic Survey, Madingly Road, Cambridge CB3 OET United Kingdom. Publisher: Geological Society of South Africa First Online: 07 Mar 2017 Online ISSN: 1996-8590 Print ISSN: 1012-0750 © 2000 Geological Society of South Africa South African Journal of Geology (2000) 103 (3-4): 237–248. https://doi.org/10.2113/1030237 Article history First Online: 07 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation S. de Villiers, J.S. Compton, M. Lavelle; The strontium isotope systematics of the Orange River, Southern Africa. South African Journal of Geology 2000;; 103 (3-4): 237–248. doi: https://doi.org/10.2113/1030237 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 SocietySouth African Journal of Geology Search Advanced Search Abstract The 87Sr/86Sr ratio of Orange River water increases from 0.7081 at its headwaters in the basalt of the Drakensberg mountains, to a value of 0.7126 before its confluence with the Vaal River tributary. The concomitant increase in Sr concentration is from 0.08 to 1.28 μM. The Vaal River, which drains Precambrian and Permian/Triassic rocks, has higher Sr concentrations, from 0.95 to 6.69 μM, and more radiogenic 87Sr/86Sr values, from 0.713 to 0.731. The geochemistry of the dissolved load of the Orange and Vaal rivers corresponds with that of the dominant catchment lithologies: Jurassic basalt, Permian/Triassic Karoo sediments and Proterozoic/Archaean para- and ortho-gneisses/granitoids. Chemical weathering rates in the Orange River system are at least a factor of 3 lower than the global average value of 36 ton/km2/yr. The highest chemical and physical weathering rates occur in the Upper Orange River, associated with high runoff and relief. In the low-relief Vaal River, chemical weathering predominates over physical weathering. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.