Geochronology and Paleoenvironmental Changes of Late Pleistocene Sediments in the Ross Sea, Antarctica

Abstract

The palaeoceanographic studies are largely limited by poor carbonate preservation in high-latitude regions. To improve our knowledge in this key area, we studied a sediment core (ANT32-RA05C) in terms of paleomagnetic and 230Th dating and geochemical properties, collected from the continental slope of the Ross Sea, Antarctica. The two major results are as follows: 1) the sedimentation rate based on 230Th isotopes is 1.37 cm/kyr, agreeing well with the correlation of the relative paleomagnetic intensity of the core ANT32-RA05C to changes in Earth’s magnetic intensity and 2) the sediments contain ice-rafted debris (IRD) over 30%, with a considerable contribution of siliceous deposits. Integrating geochronological and geochemical properties of the studied core, a correlation of the regional paleoenvironmental process to the EPICA Dome C (EDC) Antarctic temperature is established, inferring that the IRD input and primary productivity are both enhanced in a warm climate. Moreover, a leading phase of biogenic processes to changes in the ice sheet in the Ross Ice Shelf is observed, highlighting a dominant role of the oceanic circulation in the ice-sheet retreat during the last deglaciation. Overall, the sedimentary record in the Ross Sea documents some key features of the paleoenvironmental processes in the Late Pleistocene, which could be correlated with large-scale changes in Antarctica and thus are worthy of further investigation in the future.

Chronology and Sedimentary Processes in the Western Ross Sea, Antarctica since the Last Glacial Period

“…The correlation between the IRD proxies and magnetic susceptibility may be due to climate driving. Similar to the glacial-interglacial cycles of MS, during cold periods, the Ross Ice Shelf likely extended to the research sites [18,32,33], resulting in more IRDs; meanwhile, the ice-shelf front might be away from the research sites during a warm climate, leading to a decrease in IRD materials.…”

“…Climatic changes in the Southern Ocean and Antarctica are critical in Earth's climate evolution [1][2][3][4][5][6] due to their unique geographical location, environmental processes, and climate characteristics [7][8][9]. The Ross Sea is the second largest bay in the Southern Ocean (72-77 • S, 160 • E-160 • W), and studies on sediments in this key region have attracted great attention in the past [10][11][12][13][14], such as sedimentary processes, ice-shelf dynamics, sea-ice variation, and oceanic currents [15][16][17][18][19][20][21]. For instance, integrating geophysical surveys and multiple cores in the Ross [35].…”