The effect of partial pressure of carbon dioxide on anorthite dissolution.

• UTSUNOMIYA Satoshi

  Mineralogical Institute, The University of Tokyo

• MURAKAMI Takashi

  Mineralogical Institute, The University of Tokyo

• KADOHARA Hiroyuki

  Mineralogical Institute, The University of Tokyo

• TSUKIMURA Katsuhiro

  Geological Survey of Japan

Abstract

The dissolution experiment of anorthite was carried out under different partial pressures of CO₂ (P_CO<SUB>2</SUB>) to understand the role of weathering of Ca and Mg silicates in the removal of CO₂ from the atmosphere in the Precambrian. A newly-developed apparatus can control P_CO<SUB>2</SUB> in a mineral-water reaction vessel and vary P_CO<SUB>2</SUB> and temperatures from 10^−3.5 (the present atmospheric level, PAL) to 5.0 atm and from 40 to 150°C, respectively. The experiments were carried out at 150°C and pH 4.56, varying P_CO<SUB>2</SUB> from 10^−3.5 to 1.2 atm. The dissolution rate of anorthite under high P_CO<SUB>2</SUB> (=1.2 atm) is faster than that under PAL by about 4 times. Calcium and Si dissolve congruently from anorthite under PAL, whereas a Ca/Si ratio in solution is lower under high P_CO<SUB>2</SUB>. Our results suggest that the weathering rates and processes in the Archean are different from the present ones, and that the amount of Ca flux into the Archean ocean is less than that predicted assuming congruent dissolution of anorthite.

Journal

• Mineralogical Journal

  Mineralogical Journal 21 (1), 1-8, 1999

  Japan Association of Mineralogical Sciences

Keywords

• General Earth and Planetary Sciences
• General Environmental Science

Details

• CRID: 1390001206545434496
• NII Article ID: 10008773365
• NII Book ID: AA00739590
• DOI: 10.2465/minerj.21.1
• ISSN: 18814174
• ISSN: 05442540
• Text Lang: en
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed