北冰洋西部表层沉积物重矿物特征

CHARACTERISTICS OF HEAVY MINERALS IN THE SURFACE SEDIMENTS OF THE WESTERN ARCTIC OCEAN

对中国首次(1999年)和第二次(2003年)北极科学考察在楚科奇海及邻近的北冰洋深水区采取的47站表层沉积物进行了碎屑重矿物鉴定分析。结果表明北冰洋西部表层沉积物中重矿物以抗风化能力较弱的绿帘石、紫苏辉石和普通角闪石为优势矿物,钛铁矿、石榴子石、磷灰石和赤铁矿为特征矿物。矿物组合分区表明研究区物质来源和水动力变化较为复杂:白令海峡以南沉积物中重矿物含量高,水动力强;白令海峡以北的洋流变化与所经区域沉积物重矿物种类和含量变化相一致,即楚科奇海中部沉积物富集紫苏辉石、钛铁矿和石榴子石,物质来源可能与楚科奇山原相关,而在阿拉斯加沿岸沉积物中富集绿帘石和紫苏辉石,与阿拉斯加沿岸流携带物质相关;楚科奇海北部深水区碎屑矿物沉积速率低且矿物多有蚀变。

The composition, assemblage and distribution characteristics of heavy minerals in 47 surface sediment samples from the Chukchi Sea and the adjacent Arctic Ocean were identified. The sediments were collected during the first and second Chinese National Arctic Research Expeditions, in 1999 and 2003. The results show that the heavy minerals in the surface sediments of the western Arctic Ocean are mainly epidote, hypersthene and hornblende with a low resistance to weathering, and ilmenite, garnet, apatite and hematite are characteristic minerals. The mineral assemblages and distribution indicate that the material sources and the hydrodynamic conditions in the study area are complicated. The content of heavy minerals is higher in the southern part of the Bering Strait, indicating strong hydrodynamic action. The sediments in the central Chukchi Sea are enriched in hypersthene, ilmenite and garnet, the source of which may have been the Chukchi plateau, whereas in Alaska coastal sediments enriched in epidote and hypersthene may be related to the Alaska Coastal Current. The clastic mineral deposition rate in the northern Chukchi Sea deep water is low and there has been much mineral alteration.