Skip to main content
Journal cover image

Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates

Publication ,  Journal Article
Vengosh, A; Kolodny, Y; Starinsky, A; Chivas, AR; McCulloch, MT
Published in: Geochimica et Cosmochimica Acta
January 1, 1991

The abundances and isotopic composition of boron in modern, biogenic calcareous skeletons from the Gulf of Elat, Israel, the Great Barrier Reef, Australia, and in deep-sea sediments have been examined by negative thermal-ionization mass spectrometry. The selected species (Foraminifera, Pteropoda, corals, Gastropoda, and Pelecypoda) yield large variations in boron concentration that range from 1 ppm in gastropod shells to 80 ppm in corals. The boron content of the biogenic skeletons is independent of mineralogical composition and is probably related to biological (vital) effects. The δ11B values of the carbonates range from 14.2 to 32.2%. (relative to NBS SRM 951) and overlap with the δ11B values of modern deep-sea carbonate sediments (δ11B = 8.9 to 26.2%.). The variations of δ11B may be controlled by isotopic exchange of boron species in which 10B is preferentially partitioned into the tetrahedral species, and coprecipitation of different proportions of trigonal and tetrahedral species in the calcium carbonates. Carbonates with low δ11B values (~ 15%.) may indicate preferential incorporation of tetrahedral species, whereas the higher δ11B values (~30%.) may indicate 1. (1) uptake of both boron species assuming equilibrium with seawater 2. (2) preferential incorporation of B(OH)4- from in situ high-pH internal fluids of organisms that are isolated from seawater. The B content and δ11B values of deep-sea sediments, Foraminifera tests, and corals are used to estimate the global oceanic sink of elemental boron by calcium carbonate deposition. As a result of enrichment of B in corals, a substantially higher biogenic sink of 6.4 ± 0.9 × 1010 g/yr is calculated for carbonates. This is only slightly lower than the sink for desorbable B in marine sediments (10 × 1010 g/yr) and approximately half that of altered oceanic crust (14 × 1010 g/yr). Thus, carbonates are an important sink for B in the oceans being ~20% of the total sinks. The preferential incorporation of 10B into calcium carbonate results in oceanic 11B-enrichment, estimated as 1.2 ± 0.3 × 1012 per mil · g/yr. The boron-isotope composition of authigenic, well-preserved carbonate skeletons may provide a useful tool to record secular boron-isotope variations in seawater at various times in the geological record. The potential use of boron-isotope geochemistry in skeletons as a tracer for palaeoenvironments is demonstrated in Ostracoda and Foraminifera from the Gulf of Carpentaria, Australia. The δ11B values of glacial-age, buried skeletons (4.0 and 4.9%., respectively) are lower than that of their modern equivalents (17.6 and 13.3%., respectively). This may reflect a "terrestrial" boron-isotope signature of the water in the gulf during the Late Quaternary when it was isolated from the ocean. © 1991.

Duke Scholars

Published In

Geochimica et Cosmochimica Acta

DOI

ISSN

0016-7037

Publication Date

January 1, 1991

Volume

55

Issue

10

Start / End Page

2901 / 2910

Related Subject Headings

  • Geochemistry & Geophysics
  • 3705 Geology
  • 3703 Geochemistry
  • 0406 Physical Geography and Environmental Geoscience
  • 0403 Geology
  • 0402 Geochemistry
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Vengosh, A., Kolodny, Y., Starinsky, A., Chivas, A. R., & McCulloch, M. T. (1991). Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates. Geochimica et Cosmochimica Acta, 55(10), 2901–2910. https://doi.org/10.1016/0016-7037(91)90455-E
Vengosh, A., Y. Kolodny, A. Starinsky, A. R. Chivas, and M. T. McCulloch. “Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates.” Geochimica et Cosmochimica Acta 55, no. 10 (January 1, 1991): 2901–10. https://doi.org/10.1016/0016-7037(91)90455-E.
Vengosh A, Kolodny Y, Starinsky A, Chivas AR, McCulloch MT. Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates. Geochimica et Cosmochimica Acta. 1991 Jan 1;55(10):2901–10.
Vengosh, A., et al. “Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates.” Geochimica et Cosmochimica Acta, vol. 55, no. 10, Jan. 1991, pp. 2901–10. Scopus, doi:10.1016/0016-7037(91)90455-E.
Vengosh A, Kolodny Y, Starinsky A, Chivas AR, McCulloch MT. Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates. Geochimica et Cosmochimica Acta. 1991 Jan 1;55(10):2901–2910.
Journal cover image

Published In

Geochimica et Cosmochimica Acta

DOI

ISSN

0016-7037

Publication Date

January 1, 1991

Volume

55

Issue

10

Start / End Page

2901 / 2910

Related Subject Headings

  • Geochemistry & Geophysics
  • 3705 Geology
  • 3703 Geochemistry
  • 0406 Physical Geography and Environmental Geoscience
  • 0403 Geology
  • 0402 Geochemistry