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Northeastern (46th Annual) and North-Central (45th Annual) Joint Meeting (20–22 March 2011)

Paper No. 7
Presentation Time: 8:00 AM-12:00 PM

PALEOCLIMATIC AND MINERALOGICAL CHARACTERIZATION OF DOWNCORE VNIR, VIS DSR AND XRF DATA FROM THE NORTHWIND RIDGE AREA IN THE CENTRAL ARCTIC OCEAN


SIRIWARDANA, C.H.E.R.1, ORTIZ, J.D.1, POLYAK, L.2, WITTER, D.L.1 and COUNCIL, E.A.3, (1)Dept of Geology, Kent State University, Kent, OH 44242, (2)Byrd Polar Research Center, Ohio State University, Columbus, OH 43210, (3)Dept of Earth and Environmental Sciences, Wright State University, Dayton, OH 45435, csiriwar@kent.edu

Visible-Near Infrared (VNIR) and Visible (VIS) Diffuse Spectral Reflectance (DSR) spectra and XRF data were studied from sediment core P1-92AR-P25 raised from the Northwind Ridge. With its proximity to the Laurentide Ice Sheet (LIS) margin, and enhanced sediment influx, the Northwind Ridge furnishes high resolution palaeoclimatic records providing insights into the interaction of the Beaufort Gyre and Transpolar Drift circulation patterns. The core is comprised of fine-grained sediments spanning from 0 to 190 ka (depth ~ 500 cm) marking onset of MIS 6 (Polyak et al. 2009).

The study demonstrates cyclic variations in downcore mineralogy. Varimax-rotated Q-mode factor analysis of the down core VNIR data show three mineral assemblages reflecting glacial–interglacial cyclicity. Results reveal that factor 1: smectite+ muscovite +chlorite assemblage (r = 0.83), increases during interglacial periods due to fluvial input and sea-ice drift from Pacific-Siberian sites. This factor is positive correlated with Mn, a proxy for basin ventilation. Factor 2, illite+quartz+geothite assemblage (r = 0.55) increases during glacial periods due to minerals that likely delivered to the site as melt water suspension from the LIS and/or wind activity. However, the relatively low-correlation of this assemblage with its inferred components indicates the influence of additional mineral phase(s) as yet to be determined. Factor 3, a dolomite+calcite+glauconite assemblage (r = 0.87) increases during deglacial times, delivered from the LIS as coarser detrital IRD and melt water pulses discharged along Alaskan slopes.

The results are consistent with XRF Mn and visible DSR data and clay mineral cycles identified by previous studies (Yurco et al. 2010). The downcore mineralogical cyclicity provides a glacial–interglacial portrait of changes in sediment provenance and delivery mechanisms associated with changes in sea level, configurations of Arctic ice sheets and oceanic/atmospheric circulation.

Session No. 8--Booth# 18

Paleoclimatology/Paleoceanography (Posters)
Sunday, 20 March 2011: 8:00 AM-12:00 PM
Grand Ballroom/Urban Room (Omni William Penn Hotel)
Geological Society of America Abstracts with Programs. Vol. 43, No. 1, p.62
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