北冰洋西部表层沉积物矿物学特征及其物质来源

摘要

Mineralogical analysis was performed on bulk sediments from 79 surface samples using the X-ray diffraction (XRD)method.The results,in combination with data on ocean currents and the geological background,have been used to investigate the sources of the mineral assemblages.Mineral assemblages and distribution indicate that material sources in the study area are complicated:(1 )Feldspar is abundant in the sediments of the Chukchi Sea near the Bering Strait,and the source is material from the Anadyr River carried by the Anadyr Current.The sedi-ments on the western side of the Chukchi Sea are also rich in feldspar,and compared with other areas,which are also rich in hornblende,which is the result of the Anadyr Current and the Siberian Coastal Current carrying material from Siberia,where some volcanic and sedimentary rocks are present.The sediments in the eastern Chukchi Sea are rich in quartz,the sources of which are sediments from the Yukon River and the Kuskokwim River carried by the Alaska Coastal Current.The sediments in the northern Chukchi Sea are rich in quartz and carbonates,the sources of which are sediments from the Mackenzie River.(2)In the sediments of the southern and central parts of the Canada Basin,calcite and dolomite levels are very low,mainly because of the small impact of the Beaufort Gyre,which carries carbonates from the Canadian Arctic Archipelago.And compared with other area,the content of mica is also high,so the Laptev Sea is the main sediment source for the southern and central parts of the Canada Basin.In the other deep sea areas,calcite and dolomite levels are very high,because of the sediments carried by the Beaufort gyre from the Canadian Arctic Archipelago (Banks Island and Victoria Island).The Siberian Laptev Sea also provides small amounts of sediment.In addition,the Atlantic mid-water contributes some fine-grained ma-terial to the entire deep sea of the western Arctic Ocean.%对北冰洋西部79个表层沉积物样品进行了全岩X射线衍射矿物组成分析，结合洋流和地质背景，探讨各矿物分区的物质来源。矿物组合分区表明研究区物质来源变化较为复杂：（1）在楚科奇海的中部靠近白令海峡处长石含量很高，主要是阿纳德尔流携带的来自阿纳德尔河的沉积物；在楚科奇海的西侧的长石含量也较高，且与其他矿物组合分区相比，角闪石含量较高，这是因为受阿纳德尔流和东西伯利亚沿岸流的双重影响，沉积物来自西伯利亚陆地的一些高含长石的火山岩及沉积岩等。在楚科奇海的东侧，石英含量很高，来源为阿拉斯加沿岸流携带的育空河及卡斯奎姆河的沉积物。在阿拉斯加北部，碳酸盐岩和石英含量高，这与马更些河搬运的沉积物有关；（2）北冰洋西部深水区中加拿大海盆的南端和中部方解石和白云石的含量较低，说明受波弗特环流携带的加拿大北极群岛的碳酸盐影响相对较小，且与其他矿物组合分区相比，云母含量最高，说明沉积物主要来源为来自拉普捷夫海的海冰沉积物；此外，一些黏土级细粒物质可能由大西洋中层水携带而来。深水区的其他海域以方解石和白云石含量高为特点，主要受波弗特环流的影响，来源主要为加拿大北极群岛的班克斯岛和维多利亚岛；此外，还受来自西伯利亚陆架，主要是拉普捷夫海沉积物的影响。