Journal Article Distribution of detrital minerals and sediment color in western Arctic Ocean and northern Bering Sea sediments: Changes in the provenance of western Arctic Ocean sediments since the last glacial period

10 ( 4 )  , pp.519 - 531 , 2016-12
ISSN:18739652
Description
This paper describes the distribution of detrital minerals and sediment color in the surface sediments of the western Arctic Ocean and the northern Bering Sea and investigates the relationship between mineral composition and sediment provenance. This relationship was used to determine the provenance of western Arctic Ocean sediments deposited during the last glacial period. Sediment color is governed by water depth, diagenesis, and mineral composition. An a*–b* diagram was used to trace color change during diagenesis in the Arctic Ocean sediments. The mineral composition of surface sediments is governed by grain size and provenance. The feldspar/quartz ratio of the sediments studied was higher on the Siberian side than on the North American side of the western Arctic Ocean. The (chlorite + kaolinite)/illite and chlorite/illite ratios were high in the Bering Sea but decrease northwards in the Chukchi Sea. Thus, these ratios are useful for provenance studies in the Chukchi Sea area as indices of the Beaufort Gyre circulation and the Bering Strait inflow. The sediments deposited during the last glacial period have a lower feldspar/quartz ratio and a higher dolomite intensity than Holocene sediments on the Chukchi Plateau, suggesting a greater contribution of North American grains during the last glacial period.
本研究では、西部北極海および北部ベーリング海の表層堆積物の砕屑鉱物と色の分布を記載し、鉱物組成と堆積物供給源の関係を検討した。さらに、この関係にもとづき最終氷期の西部北極海堆積物の供給源を推定した。堆積物の色は水深、続成作用、鉱物組成を反映している。a*−b*図は北極海堆積物の色の続成変化をみるのに役立つ。鉱物組成は粒径と供給源に依存している。長石/石英比は西部北極海のシベリア側で高く、北米側で低い。緑泥石/イライト比はベーリング海で高く、チュクチ海を北に向かうと低くなる。したがって、これらの比はチュクチ海におけるボーフォート循環とベーリング海峡通過流の指標として用いることが可能である。チュクチ海台における最終氷期の堆積物は完新世のものに比べて長石/石英比が低く、ドロマイト量が多く、北米起源粒子が多かったことが示された。

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