HIGH RESOLUTION AGE MODEL OF LATE QUATERNARY MOUTH FAN AT PRYDZ TROUGH, EASTERN ANTARCTICA

A precise age model of a marine sediment sequence is essential for paleoceanographic reconstruction. It is critical to find out effective dating methods for sediments in high latitudes of the Southern Ocean as poor preservation of carbonates has limited the application of the widely used oxygen isotope stratigraphic methods. Here, we conducted high resolution magnetic susceptibility (MS) core scanning, X-ray fluorescence (XRF) core scanning and planktonic foram AMS ¹⁴C dating on cores of ANT29/P5-03,ANT30/P1-03,and ANT30/P1-02 collected from Prydz Trough Mouth Fan, East Antarctica during the 29^th and the 30^th Chinese National Antarctic Research Expeditions by R/V Xuelong, and found that Ba_xs is a reliable proxy for the paleo-export productivity of surface waters in the study area, which varies with global and East Antarctic climate at orbital scale. So age model of sediment sequence can be constructed by matching the Ba_xs of the sediment sequence to LR04 oxygen isotope stack²¹. We constructed the age model of ANT30/P1-02 following above method and found that the sedimentation rate of ANT30/P1-02 ranges between 0.15 to 4.76 cm/ka with a mean of 1.18 cm/kyr which is similar to the average sedimentation rate of the upper strata of core ODP1167. The highest sedimentation rate of a whole glacial cycle occurs at deglacial period. Interglacial period has relatively higher average sedimentation rate than glacial period. Correspondingly, strata of deglacial periods have bedding structures. Interglacial sediments are brighter than glacial sediments though both of glacial and interglacial sediments are massive. MS signal of sediment at the study area appears to have arbitrarily responded to the global and the local climate changes. So the strategy to construct age model of marine sediment sequences by correlating the MS signal of sediments to dust concentrations of ice cores are inapplicable at Prydz Bay area.