Oxygen Isotope Profiles in Firn Cores from Mizuho Plateau, Antarctica

Abstract

Oxygen isotope, gross β-radioactivity and stratigraphic determinations were done on firn cores from Mizuho Plateau, Antarctica. Factors controlling oxygen isotope variations in firn were discussed. From the results of gross β-activity measurements, it is obvious that the cycle in oxygen isotope profile is once a year in some areas due to the seasonal variation in oxygen isotopic composition of snowfall. In other areas, the cycle is not once a year. The following two factors are considered to affect strongly oxygen isotope variations in firn, from the results of direct stake measurements of snow accumulation and observations of surface conditions of the ice sheet. 1) changes in time of erosion, deposition and none on snow surface, 2) subsequent movement of water vapor in firn.