Structural, petrological and geochronological data from Fosdick Mountains, Marie Byrd Land - OPP0944600_MarieByrdLand_FordRanges

Research in the Marie Byrd Land addressed the question of crustal differentiation and stabilization of the continental crust of Marie Byrd Land province in West Antarctica. Through differentiation, a pile of muddy, oceanic sediments, that accumulated in deep troughs in the sea, bordering the Gondwana supercontinent, was transformed into ‘mature’ crust of West Antarctica that is dominated by granite rock. West Antarctica would be emergent above sea level, were it not for the continental ice sheet that has sufficient mass to depress a majority of WANT crust below sea level. Our contribution from West Antarctica is new and informative because the region was situated on the margin of the Gondwana supercontinent, where a vast quantity of clay- and feldspar-rich sedimentary materials had accumulated. Those sediments, we have determined, were extremely suitable for the creation of granite and stabilization of new continental crust. Our work shows that granite-formation and the crustal transformation occurred in two stages: one, approximately 350 million years ago, and the other, very rapid, event at ~ 100 million years ago; a finding that is beginning to be borne out in formerly-contiguous New Zealand and in Australia. Our geochronological and isotope data, and analysis, make it possible to explore the similarities, differences, and correlations among the once-continguous landmasses.

Project results have been disseminated broadly to the scientific community via more than 20 papers at annual scientific meetings, nine or more international peer-reviewed publications, and contributions to an online GIS database.

U-Pb, Sr, Sm-Nd, Hf and O isotope data have been collected over the course of the crustal differentiation project. Few U-Th-He data were also collected, in reconnaissance fashion. These correspond to rock sample collections from the Fosdick Mountains, that are predominantly migmatite gneisses and plutonic rocks, and a suite of granite and greywacke samples from the surrounding Ford Ranges. Sample numbers and descriptions are entered in the System for Earth SAmple Registration (SESAR) registry at http://www.geosamples.org, and can be located in through the online search routine. Geochronology/thermochronology interpretations have been made and whole rock geochemical data were obtained for selected samples. These materials have been submitted and cataloged at the Byrd Polar Research Center / anational rock repository. Geochemical and isotope data have been entered in the PetDB database at EarthChem.org. The resource at http://www.earthchem.org/petdb is searchable by region, placename, and lat lon coordinates.

Researchers who have need of physical material can contact the Polar Rock Repository via http://bprc.osu.edu/rr/loans.php or contact [e-mail] with an explanation and request to acquire more detailed descriptions, isotopic data or sample material for analytical work.