Quaternary Depositional Episodes, Western Spitsbergen, Norway: Aminostratigraphy and Glacial History

Abstract

Quaternary events interpreted from deposits along the central west coast of Spitsbergen are subdivided and correlated by amino acid enantiomeric ratios in enclosed molluscan fossils. Deposition is characterized by relatively short episodes of rapid sedimentation associated with glacial activity and high relative sea level. Depositional episodes are separated by relatively longer periods of subaerial exposure and pedogenesis. At least 5 major depositional episodes, each terminated by an emergence cycle, are identified by characteristic isoleucine epimerization ratios (aIle/Ile) in Mya truncata and Hiatella arctica. Absolute age limitations are derived by calibrating the aIle/Ile ratios against radiometrically dated samples and diagnostic faunal communities. Glacial activity and sea-level change are inferred from the facies relationships within each depositional episode. The findings place constaints on the timing and extent of Spitsbergen/Barents Sea glacial events. The 18 ka 1000 yr BP open-ocean .delta.18O minimum is not associated with extensive glacierization of the Forlandsund region of western Spitsbergen, nor did outlet glaciers of the postulated Barents Sea ice sheet reach the study area in the last 10,000 yr or more.