CHANGES IN ELEMENTAL AND PB ISOTOPIC COMPOSITIONS IN EPICA DOME C ICE CORE: CLIMATIC IMPLICATION DURING THE PAST 800,000 YEARS

Abstract

Trace elements (V, Cr, Mn, Fe, Co, Cu, Zn, As, Rb, Sr, Mo, Cd, Sb, Ba, Tl, Pb, Bi, Th and U) and Pb isotopic compositions have been determined in various sections from the EPICA (European Project for Ice Coring in Antarctica) deep ice core, covering the period from ~573 kyr BP to ~800 kyr BP, by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) and thermal ionization mass spectrometry (TIMS). Our study allows us to extend the previous Antarctic records of trace elements and Pb isotopes back to ~800 kyr BP (e.g., 1, 2). The records show well defined variations of trace element concentrations in relation to climate conditions with lower values during the interglacial periods and much higher values during the coldest periods of the last eight climatic cycles. Crustal enrichment factors indicate that the contribution from the main natural sources of atmospheric trace elements differ from one element to another and between each climatic period. The situation is also observed to be different during the interglacial periods before and after the Mid-Brunhes Event (MBE, ~430 kyr BP), suggesting that the main factors influencing the flux and sources of trace elements over the Antarctic plateau is closely linked with a progressive coupling of the climate of Antarctic and lower latitudes. The isotopic signature of Pb supports that changes in the provenance of dust from Potential Source Areas to Antarctica have occurred during the interglacial periods before and after the MBE.