关键词: 冰芯,层位,密度,柯林斯冰帽,南极

Abstract:

It was proven by the stratigraphy of two ice cores from Collins Ice Cap that the summit of Main dome(with elevation of 700m or so) belongs to warm infiltration zone,while that of Small dome(with elevation of 250m or so)to infiltration zone.A certain dating information could be found from the distribution of snow and ice layers along the ice core. The curve of density against depth for the ice core from the summit of Main dome showed regular variation corresponding to the distibution of melt features in stratigraphic record.The annual layers was roughly determined consequently.It was estimated that the accumulation rate in snow thickness at the summit of Main dome was 3-3.5m,which was about 1650-1925kg/m 2·a in water equivaleat and 2.0m/a in mean ice thickness equivalent.The transition depth of snow to ice there was 38-39m, above it density increased gradually downward,but at rather high rate below that depth, due to appearance of water table, reaching 900kg/m 3 in 5-6m interval.The density data of the ice core from the summit of Small dome showed the fluctuation between 800 and 900kg/m 3 except that of the very surface part, in which the snow and ice interleaved frequently and dust layers existed.These suggested that the accmulation rate at the summit of Small dome was about 0.7m/a in ice equivalent and the transition depth of snow to ice is 7-8m,covering about 10 year's mass cumulated.Very thick volcanic deposition layers were discovered at the depth below 40m in the ice core from the the summit of Samll dome.