Accession Number : ADA307935

Title :   Development and Application of the Mollusc Arctica Islandica as a Paleoceanographic Tool for the North Atlantic Ocean.

Descriptive Note : Doctoral thesis,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s) : Weidman, Christopher R.

PDF Url : ADA307935

Report Date : SEP 1995

Pagination or Media Count : 207

Abstract : The 14C and 180 composition of the annually banded, carbonate shell of the long-lived (+100 years) mollusc Arctica islandica are shown to be practical for reconstructing long term, high-resolution, DIC 14C and bottom temperature time histories for the continental shelves of the northern North Atlantic Ocean. However, its I3C composition is shown not to be a good recorder of ambient DIC 13C, and likely is controlled by physiology. Four shell-derived 14C time histories are reconstructed for the high-latitude North Atlantic Ocean. These records show significant spatial and temporal differences in the evolution of surface 14C between subpolar and subtropical regions, which are attributed to regional differences in mixed-layer depth and the presence of deepwater sources. A shell-derived 109-year record (1875-1983) of bottom temperatures has been reconstructed for a location near the former Nantucket Lightship (400N, 690W). The detrended annual temperature anomalies of this record show significant positive correlation with regional bottom, sea surface and air temperature anomalies. However, the shell-derived record describes a century-long cooling (approx. 10C) in contrast to a century-long warming of regional sea surface temperatures of equal magnitude. This long term divergence between surface and bottom conditions is attributed to increased seasonal stratification.

Descriptors :   *OCEAN SURFACE, *SHELLS(STRUCTURAL FORMS), *CONTINENTAL SHELVES, *SEA WATER, *OCEANOGRAPHY, *CARBONATES, *PALEOCLIMATOLOGY, CONTROL, ANOMALIES, SOURCES, TEMPERATURE, ATMOSPHERIC TEMPERATURE, TIME, CORRELATION, SEASONAL VARIATIONS, HISTORY, ISOTOPES, MARINE BIOLOGY, PHYSIOLOGY, CLIMATOLOGY, SURFACE TEMPERATURE, HIGH LATITUDES, STRATIFICATION, NORTH ATLANTIC OCEAN, DEEP WATER, BOTTOM, ISOTOPE EFFECT, CORAL, RADIOCARBON DATING.

Subject Categories : Ecology
      Inorganic Chemistry
      Physical and Dynamic Oceanography
      Structural Engineering and Building Technology

Distribution Statement : APPROVED FOR PUBLIC RELEASE