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Title: Mollusk-isotope records of Plio-Pleistocene marine paleoclimate, U. S. Middle Atlantic Coastal Plain

Stable oxygen and carbon isotope profiles from fossil scallop shells provide detailed paleoenvironmental information for the Pliocene and early Pleistocene of the Middle Atlantic Coastal Plain. Scallop specimens were collected from strata which represent at least five major marine transgressions. Minimum and maximum paleotemperatures were calculated from the {delta}{sup 18}O ranges recorded in each shell profile, after adjusting for changes in seawater {delta}{sup 18}O related to changes in global ice volume. Paleotemperature ranges from each stratigraphic unit were compared with modern conditions on the shelves of the Middle and South Atlantic Bight, and with paleotemperatures estimated by Hazel (1971b, 1988) from the ostracode faunas. The mollusk-isotope records indicate that the marine climate of the Atlantic Shelf was mild temperate during the deposition of the Sunken Meadow Member of the Yorktown Formation in the early Pliocene. The climate became warm temperate during the middle and late Pliocene transgressions which deposited the Rushmere, Morgarts Beach and Moore House Members of the Yorktown Formation and the Chowan River Formation. During the deposition of the James City Formation in the early Pleistocene, temperatures returned to a mild temperate climate similar to that of the modern Virginia Bight shelf. The character of the isotope profilesmore » indicates that hydrographic conditions were generally stable and similar to those of the modern Middle Atlantic Bight. The {delta}{sup 13}C profiles of most of the shells show trends suggestive of spring phytoplankton blooms and summer water-column stratification. Anomalies in several profiles are interpreted as reduced salinity events, probably related to river discharge, which most commonly occur in the spring. There is no convincing evidence in the shell profiles for upwelling.« less
Authors:
 [1]
  1. (Univ. of South Carolina, Columbia (USA))
Publication Date:
OSTI Identifier:
5504776
Resource Type:
Journal Article
Resource Relation:
Journal Name: Palaois; (United States); Journal Volume: 5:4
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; MOLLUSCS; ISOTOPE RATIO; PLEISTOCENE EPOCH; PALEOCLIMATOLOGY; PLIOCENE EPOCH; CARBON 13; CONTINENTAL SHELF; DEPOSITION; EAST COAST; FOSSILS; GEOLOGIC FORMATIONS; GEOLOGIC HISTORY; GEOLOGIC STRATA; MID-ATLANTIC BIGHT; OXYGEN 18; PALEOTEMPERATURE; SALINITY; SAMPLING; SEA LEVEL; SEAWATER; SEDIMENTARY ROCKS; STRATIGRAPHY; USA; ANIMALS; AQUATIC ORGANISMS; ATLANTIC OCEAN; CARBON ISOTOPES; CENOZOIC ERA; CONTINENTAL MARGIN; DEVELOPED COUNTRIES; EVEN-EVEN NUCLEI; EVEN-ODD NUCLEI; GEOLOGIC AGES; GEOLOGIC STRUCTURES; GEOLOGY; HYDROGEN COMPOUNDS; INVERTEBRATES; ISOTOPES; LEVELS; LIGHT NUCLEI; NORTH AMERICA; NUCLEI; OXYGEN COMPOUNDS; OXYGEN ISOTOPES; PALEONTOLOGY; QUATERNARY PERIOD; ROCKS; SEAS; STABLE ISOTOPES; SURFACE WATERS; TERTIARY PERIOD; WATER 580000* -- Geosciences