Provenance and temporal variability of ice rafted debris in the Indian sector of the Southern Ocean during the last 22,000 years

Abstract

Ice rafted debris (IRD) records were studied in two sediment cores (SK200/22a and SK200/27) from the sub-Antarctic and Polar frontal regime of the Indian sector of Southern Ocean for their distribution and provenance during the last 22,000 years. The IRD fraction consists of quartz and lithic grains, with the lithic grains dominated by volcaniclastic materials. IRD content was high at marine isotope stage 2 but decreased dramatically to near absence at the Termination 1 and the Holocene. The concentration of IRD at glacial section of the core SK200/27 was nearly twice that of SK200/22a. Moreover, IRD were more abundant at the last glacial maxima (LGM) in SK200/27 with its peak abundance proceeding by nearly two millennia than at SK200/22a. It appears that an intensification of Antarctic glaciation combined with a northward migration of the Polar Front during LGM promoted high IRD flux at SK200/27 and subsequent deglacial warming have influenced the IRD supply at SK200/22a. Quartz and lithic grains may have derived from two different sources, the former transported from the Antarctic mainland, while the latter from the islands of volcanic origin from Southern Ocean. Sea-ice, influenced by the Antarctic Circumpolar Current is suggested to be a dominant mechanism for the distribution of lithic IRD in the region.

First records of winter sea ice concentration in the southwest Pacific sector of the Southern Ocean

“…The paleo winter sea ice estimates for cores (a) SO136‐111 and (b) E27‐23 (solid blue lines) are plotted against the sea‐surface temperature record from (c) De Deckker et al []. The Scotia Sea sediment flux reported by Weber et al [] is shown in Figure d and the Indian Ocean IRD record of Manoj et al [] is shown in Figure e (brown lines). The TALDICE δ 18 O record from Stenni et al [] is shown in Figure f (purple line).…”

“…Locations for the TALDICE and EPICA Dome C ice cores and marine sediment cores SO136-111, E27-23 (from the southwest Pacific), TN057-13PC4, PS2090/1094, and PS1654/1093 (from the Atlantic) are also indicated. (Cores SK200/27 [Manoj et al, 2013] and MD07-3134 [Weber et al, 2014], used to examine IBRD records, are identified.) Paleoceanography 10.1002/2014PA002764 FERRY ET AL.…”

“…The Antarctic Cold Reversal (ACR) refers to a period of climatic cooling between 14.5 and 12.5 kyr B.P., which interrupted the transition from the Last Glacial Maximum into deglacial conditions [Stenni et al, 2001;Divine et al, 2010]. The ACR has been previously identified from variations to ice rafted debris [Manoj et al, 2013;Weber et al, 2014] (Figures 6d and 6e), δ 18 O data from the TALDICE ice core [Stenni et al, 2010] (Figure 6f), opal flux records within the south Atlantic [Anderson et al, 2009] and from diatom assemblages within lake sediments of southern South America [Recasens et al, 2015]. Regionally, SST's south of Australia suggest cooling due to the decreasing influence of the Leeuwin Current at 14.5 and 11.8 kyr B.P.…”

Palaeoclimatic records from Antarctica and Southern Ocean: A review of Indian contributions

“…The ice core proxy based reconstruction revealed significant changes in Southern Hemispheric climate during the past several hundreds of years (Naik et al, 2010 a, b;Thamban et al, 2011 a,b;Thamban et al, 2013). The study revealed utility of shallow ice cores in reconstructing the past changes in major climatic modes like the El Niño Southern Oscillation (ENSO) and Southern Annular mode (SAM) (Naik et al, 2010 a).…”

“…The early results suggested that shallow ice cores are indeed useful for regional climate reconstruction through a careful selection of core sites and a focussed study of proxy parameters (Nijampurkar et al, 2002;Thamban et al, 2006;Laluraj et al, 2009). The annually dated highresolution (annual) ice core studies revealed the utility of ice records to reconstruct the natural environmental processes as well as the polar and extra-tropical climatic teleconnections during the past hundreds of years (Naik et al, 2010 a,b;Thamban et al, 2011 a,b;Thamban et al, 2013;Antony et al, 2012;Laluraj et al, 2011;Laluraj et al, 2014;PAGES 2k Consortium, 2013;Rahaman et al, 2016). The increased focus on the well-dated ice cores from high accumulation regions of coastal Antarctica have improved our understanding on the recent climate variability in Antarctica and forcing mechanisms.…”