关键词: 南极;乔治王岛;冰芯;火山喷发;记录

Abstract:

Careful mineral and structural analyses have revealed the characteristics of volcanic ash in the 9 horizons of a 80.2m ice core from Collins Ice Cap,King George Island,Antarctica. Under the assumption of steady state,Dansgaard Johnsen flow model was employed to date the core. The volcanic eruptive sequence established for South Shetland Islands region since A.D.1650 shows that 7 volcanic eruptive cycles could be distinguished during the past 340 years,as covered by the ice core. It seems that during the period of 1875-1925 there were frequent volcanic activities,with perhaps many eruptions at the Deception Island. The years between A.D.1650 to A.D.1800 appeared to be a quiet period,followed by an unsteady century in volcanic action. The past century is basically a tranquil era except for two turbulent epochs at the beginning of the century and in the 1950-70s. Many of the volcanic eruptions in the ice core sequence are found in the previously reported records for this region. A few of that are not in the records should be further investigated. The absence of 1967-1970 eruptive trace in the core suggests that the volcanic eruptions obtained by present study could still be the minimum number of the actual eruptions,although the general outline was exhibited by present study.