Boron isotope variations during fractional evaporation of sea water: New constraints on the marine vs. nonmarine debate

Research Article| September 01, 1992 Boron isotope variations during fractional evaporation of sea water: New constraints on the marine vs. nonmarine debate Avner Vengosh; Avner Vengosh 1Research School of Earth Sciences, Australian National University, G.P.O. Box 4, Canberra, ACT 2601 Australia Search for other works by this author on: GSW Google Scholar Abraham Starinsky; Abraham Starinsky 2Department of Geology, Hebrew University, Jerusalem 91904, Israel Search for other works by this author on: GSW Google Scholar Yehoshua Kolodny; Yehoshua Kolodny 2Department of Geology, Hebrew University, Jerusalem 91904, Israel Search for other works by this author on: GSW Google Scholar Allan R. Chivas; Allan R. Chivas 1Research School of Earth Sciences, Australian National University, G.P.O. Box 4, Canberra, ACT 2601 Australia Search for other works by this author on: GSW Google Scholar Menahem Raab Menahem Raab 3Geological Survey of Israel, 30 Malkhe Yisrael Street, Jerusalem 95501, Israel Search for other works by this author on: GSW Google Scholar Author and Article Information Avner Vengosh 1Research School of Earth Sciences, Australian National University, G.P.O. Box 4, Canberra, ACT 2601 Australia Abraham Starinsky 2Department of Geology, Hebrew University, Jerusalem 91904, Israel Yehoshua Kolodny 2Department of Geology, Hebrew University, Jerusalem 91904, Israel Allan R. Chivas 1Research School of Earth Sciences, Australian National University, G.P.O. Box 4, Canberra, ACT 2601 Australia Menahem Raab 3Geological Survey of Israel, 30 Malkhe Yisrael Street, Jerusalem 95501, Israel Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1992) 20 (9): 799–802. https://doi.org/10.1130/0091-7613(1992)020<0799:BIVDFE>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 Avner Vengosh, Abraham Starinsky, Yehoshua Kolodny, Allan R. Chivas, Menahem Raab; Boron isotope variations during fractional evaporation of sea water: New constraints on the marine vs. nonmarine debate. Geology 1992;; 20 (9): 799–802. doi: https://doi.org/10.1130/0091-7613(1992)020<0799:BIVDFE>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 Examination of boron isotopes, elemental B, Br, and Li in brines, and coprecipitated salts during fractional evaporation of sea water shows that Br, Li, and B in the evaporated sea water have lower concentrations than expected, as determined from mass-balance calculations. The deficiency is found beyond a degree of evaporation of ∼30 and is associated with a gradual increase in the δ11B values of the evaporated sea water, from 39‰ to 54.7‰ (relative to standard NBS 951). The high δ11B values of the brines and the relatively lower δ11B values of the coexisting precipitates (MgSO4 and K-MgSO4 salts; δ11B = 11.4‰ to 36.0‰) suggest selective uptake of 10B by the salts. Applying Rayleigh distillation equations, the empirical fractionation factors for the depletion of the salts in 11B are estimated as 30‰ (α = 0.969) for the early stages of precipitation (gypsum and halite range) and 20‰ (α = 0.981) for the late stages (K-MgSO4 minerals). Coprecipitation of B(OH)4- species with the salts, and/or precipitation of Mg-borate minerals with a coordination number of 4 are the proposed mechanisms for boron isotope fractionation during fractional evaporation of sea water. The boron isotope composition of sea water (δ11B = 39‰) is significantly higher than that of continental water (δ11B = -3‰ ±5‰). Our study shows that salt deposits may be depleted in 11B by 20‰ to 30‰ relative to their parent brines. These variations suggest that boron isotopes can be used to determine the origin (marine vs. nonmarine) of brines and ancient evaporitic environments. 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.