Sea ice extent and seasonality for the Early Pliocene northern Weddell Sea

Abstract

17Growth increment analysis coupled with stable isotopic data (δ 18 O/δ 13 C) from Early Pliocene (ca 4.7 Ma) 18Austrochlamys anderssoni from shallow marine sediments of the Cockburn Island Formation, northern

The PRISM (Pliocene palaeoclimate) reconstruction: time for a paradigm shift

“…Studies of Pliocene marine environmental conditions reconstructed from ontogenetic profiles of oxygen isotopic composition (δ 18 O) have been gradually emerging [93][94][95][96], and this approach has recently been supplemented by the use of evidence from microgrowth increments [97][98][99]. These applications of ontogenetic time-series data from mineralized tissue (sclerochronology) allow for reconstruction of annual seafloor temperature range, absolute seafloor temperatures, reconstructed surface water temperature and, by inference, sea ice extent [97][98][99]. In addition, carbon isotope (δ 13 C) profiles may provide an indication of seasonal phytoplankton dynamics.…”

“…Breakthroughs in drilling methods by ANtarctic DRILLing project (ANDRILL) have allowed access to marine successions deep under the ice shelves that provide proximal and nearly continuous records of dynamic ice sheet conditions [116]. Multiple proxy data from ANDRILL are being incorporated into PRISM, providing a unique high-resolution framework into which bryozoan-and mollusc-derived palaeoclimate records of seasonal variability from the Antarctic Peninsula [98,103] can be incorporated. These shortterm, seasonally resolved data will help provide a new understanding of temporal and spatial variability of the Antarctic cryosphere and its concomitant effects on the global climate system.…”

Fossil proxies of near-shore sea surface temperatures and seasonality from the late Neogene Antarctic shelf

“…Proxies for bivalves (e.g. A. anderssoni in Williams et al (2010) or indirectly using species tolerances (e.g. dolphin fossils in Quilty et al (1990), suggest that there was a reduction in sea ice during warmer intervals.…”

“…There are no modern detailed studies of meltwater flux around James Ross Island, from which the most extensive Neogene fossil assemblages are derived. By contrast, meltwater fluxes are well constrained for surface water in the western Antarctic Peninsula region in Marguerite Bay at 68°S Williams et al 2010). The north end of Marguerite Bay is covered by winter sea ice for several months, which provides a useful comparison for seasonal meltwater fluxes from sea ice and glacial sources into the modern James Ross Island area, despite different geographical settings.…”

“…Though the stratigraphic record of the source deposits and of the fossil materials themselves are often fragmentary, we have compared these with reconstructed sea temperatures for several time intervals in the late Neogene (e.g. Ciesielski and Weaver 1974;Clark et al 2010;Williams et al 2010). We also assess peak summer temperatures and sea ice extent during warm climate intervals in the late Neogene.…”