Physiological and environmental factors related to carbon isotopic variations in mollusc shell carbonate

Conference · Tue Jan 01 00:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6317300

Krantz, D E; Williams, D F; Jones, D S

The carbon isotopic composition of mollusc shell carbonate has been used as a general environmental indicator in numerous studies, but relatively little is known of the factors which affect within-shell variation. Primary control of delta/sup 13/C values in shell carbonate comes from the dissolved bicarbonate source, particularly as related to marine versus fresh water. Present models explain cyclic variations in the delta/sup 13/C profiles of mollusc shells due to upwelling, phytoplankton productivity and stratification, disequilibrium with rapid shell growth, and infaunal versus epifaunal habitat. Carbon and oxygen isotopic profiles in this study were obtained from specimens of Spisula solidissima (surf clam) and Placopecten magellanicus (sea scallop) collected alive from 14 to 57 m water depths off the Virginia coast. Three main factors appear to affect the delta/sup 13/C profiles in these specimens. Isotopically light values commonly associated with the spring and occasionally the fall correspond with seasonal phytoplankton productivity. A significant negative delta/sup 13/C offset of the infaunal Spisula relative to the epifaunal Placopecten probably relates to the inclusion of isotopically more negative pore-water bicarbonate by Spisula. Additionally, occasional transient spikes in both the delta/sup 18/O and delta/sup 13/C profiles correspond to intrusion of reduced-salinity water.

• Research Organization: Univ. of South Carolina, Columbia (USA)
• OSTI ID: 6317300
• Report Number(s): CONF-8510489-
• Journal Information: Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
EXOSKELETON
BIOGEOCHEMISTRY
CHEMICAL COMPOSITION
MOLLUSCS
CARBON ISOTOPES
CARBONATE MINERALS
ISOTOPE RATIO
OXYGEN ISOTOPES
SEASONAL VARIATIONS
VIRGINIA
ANIMALS
AQUATIC ORGANISMS
BODY
CHEMISTRY
FEDERAL REGION III
GEOCHEMISTRY
INVERTEBRATES
ISOTOPES
MINERALS
NORTH AMERICA
ORGANS
SKELETON
USA
VARIATIONS
580400* - Geochemistry- (-1989)