Mineralogical, geochemical and magnetic signatures of surface sediments from the Canadian Beaufort Shelf and Amundsen Gulf (Canadian Arctic)

Mineralogical, geochemical, magnetic, and siliciclastic grain-size signatures of 34 surface sediment samples from the Mackenzie-Beaufort Sea Slope and Amundsen Gulf were studied in order to better constrain the redox status, detrital particle provenance, and sediment dynamics in the western Canadian Arctic. Redox-sensitive elements (Mn, Fe, V, Cr, Zn) indicate that modern sedimentary deposition within the Mackenzie-Beaufort Sea Slope and Amundsen Gulf took place under oxic bottom-water conditions, with more turbulent mixing conditions and thus a well-oxygenated water column prevailing within the Amundsen Gulf. The analytical data obtained, combined with multivariate statistical (notably, principal component and fuzzy c-means clustering analyses) and spatial analyses, allowed the division of the study area into four provinces with distinct sedimentary compositions: (1) the Mackenzie Trough-Canadian Beaufort Shelf with high phyllosilicate-Fe oxide-magnetite and Al-K-Ti-Fe-Cr-V-Zn-P contents; (2) Southwestern Banks Island, characterized by high dolomite-K-feldspar and Ca-Mg-LOI contents; (3) the Central Amundsen Gulf, a transitional zone typified by intermediate phyllosilicate-magnetite-K-feldspar-dolomite and Al-K-Ti-Fe-Mn-V-Zn-Sr-Ca-Mg-LOI contents; and (4) mud volcanoes on the Canadian Beaufort Shelf distinguished by poorly sorted coarse-silt with high quartz-plagioclase-authigenic carbonate and Si-Zr contents, as well as high magnetic susceptibility. Our results also confirm that the present-day sedimentary dynamics on the Canadian Beaufort Shelf is mainly controlled by sediment supply from the Mackenzie River. Overall, these insights provide a basis for future studies using mineralogical, geochemical, and magnetic signatures of Canadian Arctic sediments in order to reconstruct past variations in sediment inputs and transport pathways related to late Quaternary climate and oceanographic changes.针对加拿大北极西部麦肯齐-博福特海坡与阿蒙森湾的34个表层沉积物样品，本研究对其矿物学、地球化学、磁学及硅质碎屑粒度特征展开分析，以期更精准地限定该区域的氧化还原状态、碎屑物源与沉积动力过程。氧化还原敏感元素（Mn、Fe、V、Cr、Zn）的分析结果显示，麦肯齐-博福特海坡与阿蒙森湾的现代沉积作用均发生于有氧底水环境之中；其中阿蒙森湾混合作用更为强烈，水体整体处于充分氧化状态。所获得的分析数据，结合多元统计分析（尤其是主成分分析与模糊C均值聚类分析）及空间分析方法，将研究区划分为4个沉积组成特征迥异的单元：（1）麦肯齐海槽-加拿大博福特陆架区：以高含量层状硅酸盐-铁氧化物-磁铁矿以及Al-K-Ti-Fe-Cr-V-Zn-P组分为特征；（2）班克斯岛西南区：以高含量白云石-钾长石以及Ca-Mg-烧失量（Loss on Ignition，LOI）组分为特征；（3）阿蒙森湾中部过渡带：以中等含量的层状硅酸盐-磁铁矿-钾长石-白云石以及Al-K-Ti-Fe-Mn-V-Zn-Sr-Ca-Mg-烧失量（LOI）组分为典型特征；（4）加拿大博福特陆架泥火山区：以分选较差的粗粉砂为特征，且石英-斜长石-自生碳酸盐以及Si-Zr组分含量较高，同时磁化率值偏高。本研究结果同时证实，加拿大博福特陆架现今的沉积动力过程主要受麦肯齐河沉积物供给的调控。综上，本研究的认识可为未来利用加拿大北极沉积物的矿物学、地球化学与磁学特征，重建与晚第四纪气候及海洋变化相关的沉积物输入与搬运路径的历史演变提供研究基础。