关键词: 南设得兰群岛;海洋沉积物岩芯;矿物组合;沉积作用;物质来源

Abstract:

There are more than thirty of detrital minerals in sediments of core S11. Analysis of heavy mineral assemblages reveals that pyroxene and amphibole are the dominant heavy minerals in the sediments. The feldspar and quartz are the dominant light minerals. According to the characteristics of the detrital mineral assemblages in the vertical direction, four types of heavy mineral assemblages can be found: 1) Pyroxene-amphibole-epidote-garnet, 2) Pyroxene-amphiple-epidote-authigenic pyrite, 3) Amphibole-pyroxene-epidote-sheet minerals, 4) Pyoxene-amphibole-epidote-sheet minerals-authigenic pyrtite.And two light mineral assemblges: 1) feldspar-quartz-volcanic glass fragment, and 2) feldspar-quartz were defined. The mineralogical characteristics of sediments show their specific source rocks. On the basis of the different mineral assemblages, the sediments in core S11 consist of four layers from the uppermost part to the lower part as follow: 1) Upper layer of pyroclastic minerals, 0-125cm; 2) Middle layer of pyroclastic minerals, 125-255cm; 3) The layer of pyroclastic minerals (pelagic sands), 255-282cm; 4) Lower layer of pyroclastic minerals, 282-341cm. The source of the pelagic sands was discussed in this paper. The materials of layers 1,2 and 4 have possibly come from intermediate-basic volcanic rocks and volcanic eruptions on the South Shetland Islands. The sediments of layer 3 mainly come from intermediate-acidic igneous rocks on Antarctic Peninsala. Thus they might be formed by turbidite sedimentation.