关键词: 南极,布兰斯菲尔德海峡,硅藻氧同位素,地层学

Abstract:

Fiftyone diatom samples taken from the piston core PC10 in the Bransfield Strait of West Antarctica were engaged in oxygen isotope analysis. Among them 49 samples yielded relatively good results and 2 samples showed unsatisfied results due to insufficient diatom for analysis need.The δ 18 O values of 49 samples range from 35.32 to 24.30‰(SMOW).Not only the values are systematically lower,but also the spread in δ 18 O is larger than those for late Quaterary diatom reported by other researchers. It is most likely that they were caused by a slightly higher zeolite,quartz and albite in parts of sample identified by X ray diffraction analysis. However the comprehensive study on sedimentary proxies,especially on the correlation analysis between δ 18 O values and diatom (amorphous) contents show evidentially that the impurities within samples have not changed essentially the information of ecological environment reflected by δ 18 O values. The diatom based recults reveal that the 753cm long sediments of core PC10 printed the deposition of this area during the last 112.5 kaB.P.,representing oxygen isotope stages 1-5 and including one incomplete glacial/interglacial cycle and postglacial period. The sedimentary rate in interglacials seem a little higher than that in glacial,owing to the more terrigenous supply by ice rafting during the interglacial stages.