Boron isotopic composition and concentration in modern marine carbonates

Journal Article · Wed Jan 01 04:00:00 EST 1992 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(92)90151-8· OSTI ID:7278344

Hemming, N G; Hanson, G N ^[1]

---

1. State Univ. of New York, Stony Brook (United States)

The boron isotopic compositions and boron concentrations of selected modern marine carbonates were analyzed by negative thermal ionization mass spectrometry with a 2{sigma} reproducibility of standards and samples better than 0.7{per thousand}. It was found that the boron isotopic compositions of modern marine carbonates fall within a relatively narrow range (+22.1 {plus minus} 3{per thousand} relative to NBS SRM951 boric acid standard) for all samples (biogenic, nonbiogenic, warm water, cold water, aragonitic, or calcitic). This is about 17{per thousand} lighter than seawater. This indicates that mineralogy, temperature, and vital effects are not primary controls on the observed isotopic composition. The narrow range in isotopic composition is no contrast to the wide range in boron concentrations of these samples (10.9-71.4 ppm). The boron isotopic compositions and boron concentrations in modern marine carbonates are consistent with preferential adsorption of the isotopically lighter B(OH){sub 4}{sup 1 {minus}} aqueous species over the B(OH){sub 3} species before incorporation into the carbonate site. Because there is a pH control on the availability of B(OH){sub 4}{sup 1{minus}}, the result is a pH control on the boron abundance in the carbonates. Possible second-order biomineralogic controls on pH may account for boron concentrations in calcareous organisms that produce low pH microenvironments at the site of CaCO{sub 3} precipitation.

• DOE Contract Number: FG02-85ER13416
• OSTI ID: 7278344
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 56:1; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540310 -- Environment
Aquatic-- Basic Studies-- (1990-)
58 GEOSCIENCES
580000* -- Geosciences
ADSORPTION
BORON 10
BORON 11
BORON COMPOUNDS
BORON HYDROXIDES
BORON ISOTOPES
CALCITE
CARBONATE MINERALS
CARBONATE ROCKS
CHEMISTRY
COMPARATIVE EVALUATIONS
DATA
EVALUATION
EXPERIMENTAL DATA
GEOCHEMISTRY
HYDROGEN COMPOUNDS
HYDROXIDES
INFORMATION
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MASS SPECTROSCOPY
MINERALOGY
MINERALS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OXYGEN COMPOUNDS
PH VALUE
QUANTITY RATIO
RESERVOIR TEMPERATURE
ROCKS
SEAWATER
SEDIMENTARY ROCKS
SORPTION
SPECTROSCOPY
STABLE ISOTOPES
WATER