Development of a High Precision Chronostratigraphic Framework to Connect Antarctic Glacial and Climatic History with Global Proxy Records

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This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports development of a basic chronostratigraphic framework for microfossils from the Southern Ocean and Antarctic continental shelf. Chronostratigraphic data from the Antarctic shelf and Southern Ocean have advanced to the point where a substantial update and integration is required to realize their full potential in age resolution and to meet the demands of future drilling initiatives (as embodied in ANDRILL and SHALDRIL). Questions to be addressed by ANDRILL and SHALDRIL are pertinent today and critical to understand the mechanism and pace of significant changes in the Antarctic ice sheets. Antarctica is integrally linked to the global system through vertical and horizontal ocean circulation, albedo reflectivity, glacioeustatic control on paleogeography of coastal regions, and atmospheric exchange. In order to understand how the ice sheet has responded to, and influenced, the global climate system, it is vital that we possess the best tools for time resolution and long distance correlation of geological, and particularly paleontological, data. Application of graphic correlation to these data will enable the development of a powerful chronostratigraphic tool, the Composite Standard Reference Section (CSRS), which can manage diverse and complex stratigraphic datasets with relative ease, and have strong application across the subtropical to Antarctic latitudinal gradient. The work supported by this grant will develop a high precision chronostratigraphy and provide the means to apply this single integrated system to the diverse types of data generated by Antarctic drilling. The principal aim is to serve the ANDRILL and SHALDRIL scientific community by constructing a stratigraphic framework that will provide a conduit for information transfer between the high and low latitudes.An experienced team of biostratigraphers is committed to revisiting some of the important sedimentary sections retrieved over the past 30 years and updating them into a modern taxonomic and chronostratigraphic database. In addition, the results of parallel, on-going studies of Southern Ocean radiolarians and foraminifers by Chris Hollis and James Crampton of New Zealand will be integrated into the database. The broad chronostratigraphic synthesis we propose for Antarctic and Southern Ocean records is mirrored in the Atlantic Ocean by SYNATLAN, which offers promise to carry our synthesis and Antarctic paleoclimatic information within and beyond the equatorial Atlantic Ocean. The CHRONOS project will serve to integrate this and other global databases. This project will develop a Composite Standard Reference Section (CSRS) for the Indian sector of the Southern Ocean along a latitudinal transect. Diatom, calcareous nannofossil, palynomorph and foraminiferal biostratigraphic events will form the main body of the data. Selected input of other stratigraphic data (magnetostratigraphy, chemostratigraphy, tephrochronology) will enhance the chronostratigraphic precision. The robustness of the CSRS as a chronostratigraphic model will be tested against the records from selected sites in the Atlantic sector of the Southern Ocean. Once tested and refined, this CSRS will then serve as a template for the temporal placement of Antarctic shelf records derived largely from the Ross Sea. This approach will result in improvement in chronostratigraphic resolution, will link distinct biogeographic provinces into one network of sequential events, will propose numerous new species to remedy the plethora of informal diatom names, and will provide a common reference scheme for communication between scientists working on diverse data sets and in different parts of the world. All of these outcomes will facilitate the training of new scientists.