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North-Central Section - 46th Annual Meeting (23–24 April 2012)

Paper No. 2
Presentation Time: 9:20 AM

DOWNCORE CA-P-I SIGNATURES DISCRIMINATE TEMPORAL AND GEOGRAPHIC VARIATIONS IN LATE PLEISTOCENE CARBONATE PROVENANCE IN THE ARCTIC OCEAN


SIRIWARDANA, C.H.E.R.1, ORTIZ, J.D.2, POLYAK, L.3, COUNCIL, E.A.4, GRIFFITH, E.M.1 and DARBY, D.A.5, (1)Department of Geology, Kent State University, Kent, OH 44242, (2)Dept of Geology, Kent State University, Kent, OH 44242, (3)Byrd Polar Research Center, Ohio State University, Columbus, OH 43210, (4)Dept. of Earth and Environmental Sciences, Wright State University, Dayton, OH 45435, (5)Department of Ocean, Earth, & Atmospheric Sciences, Old Dominion University, 4600 Elkhorn Ave, Norfolk, VA 23529-0276, csiriwar@kent.edu

Patterns of detrital carbonate sedimentation in the Arctic Ocean reveal a specific paleoclimatic linkage with the Laurentide Ice Sheet. Detrital carbonates are mainly derived from erosion of the Laurentide ice sheet, entering the Arctic along the Canadian Arctic Archipelago via the Beaufort Gyre (BG), in contrast to carbonate-poor Eurasian sources indicative of Transpolar Drift (TPD) circulation.

The characteristics of detrital carbonate in Arctic sediment has been studied using downcore Ca, P and I data measured by X-Ray Fluorescence (XRF) from 13 Healy-Oden TransArctic Expediton (HOTRAX) cores. Analysis of Ca vs. P and Ca vs. I cross-plots from each HOTRAX core document distinct linear relationships with slopes that can be used to differentiate between their geographic locations. These cross plots indicate a low Ca vs. P and Ca vs. I values during interglacial intervals, as opposed to high values during glacial intervals. The slope of the Ca-P-I relationship varies in response to the core’s proximity to the source region. Variation of Ca-P-I ratios from fossil marine biota do not play a significant role in determining these regional patterns as detrital carbonate IRD dominates due to poor biogenic carbonate preservation.

The downcore distribution of carbonate pulses can be used as an effective tool to map temporal and geographic variations of BG and TPD circulations. Downcore Ca/P and Ca/I molar ratios, which reflect temporal paleoclimatic changes, identify all known carbonate pulses of deglacial IRD origin providing insights into the relative importance of the TPD and BG at each location with time. Pleistocene sedimentation in the Eurasian Basin exhibits fewer carbonate spikes (>100 Ca/I or 1 Ca/P molar ratios), occurring frequently during recent glaciations characteristic of the lower abundance of Laurentide materials delivered to the Eurasian basin by a weakened BG and stronger TPD.

P and I distributions in the Canada basin practically mimic that of Ca, but Ca/P, Ca/I ratios could potentially improve our understanding of Laurentide-sourced sediments in the Eurasian basin. Analysis of the composition of Canadian source rocks and core sediments will help to pinpoint the specific location of the source region in the North American craton.

Session No. 22

T16. Climate Change: Past, Present and Future
Tuesday, 24 April 2012: 9:00 AM-12:00 PM
Room 202 (Dayton Convention Center)
Geological Society of America Abstracts with Programs. Vol. 44, No. 5, p.63
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