Oxygen and carbon isotope disequilibria in Galapagos corals: isotopic thermometry and calcification physiology

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6997034

McConnaughey, T A

Biological carbonate skeletons are built largely from carbon dioxide, which reacts to form carbonate ion within thin extracellular solutions. The light isotopes of carbon and oxygen react faster than the heavy isotopes, depleting the resulting carbonate ions in /sup 13/C and /sup 18/O. Calcium carbonate precipitation occurs sufficiently fast that the skeleton remains out of isotopic equilibrium with surrounding fluids. This explanation for isotopic disequilibrium in biological carbonates was partially simulated in vitro, producing results similar to those seen in non-photosynthetic corals. Photosynthetic corals have higher /sup 13/C//sup 12/C ratios due to the preferential removal of /sup 12/C (as organic carbon) from the reservoir of dissolved inorganic carbon. The oxygen isotopic variations in corals can be used to reconstruct past sea surface temperatures to an accuracy of about 0.5/sup 0/C. The carbon isotopic content of photosynthetic corals provides an indication of cloudiness. Using isotopic data from Galapagos corals, it was possible to construct proxy histories of the El Nino phenomenon. The physiology of skeletogenesis appears to be surprisingly similar in calcium carbonate, calcium phosphate, and silica precipitating systems.

• Research Organization: Washington Univ., Seattle (USA)
• OSTI ID: 6997034
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580500* -- Oceanography-- (1980-1989)
ACCURACY
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON 12
CARBON 13
CARBON COMPOUNDS
CARBON ISOTOPES
CARBONATES
CNIDARIA
CORALS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FORECASTING
HYDROGEN COMPOUNDS
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
NUCLEI
OCEANOGRAPHY
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PALEOCLIMATOLOGY
PALEONTOLOGY
SEAWATER
STABLE ISOTOPES
WATER