An X-ray diffraction Approach : Bulk mineral assemblages as provenance indicator of sediments from the Arctic Ocean

Paleoclimate research and climate models demonstrate that the Arctic is very sensitive to climate change and also plays a key role in driving and amplifying global climate variability and sea-level change. Study of the late Quaternary paleoceanography in the Arctic Ocean is of great importance to understand the glacial-interglacial climate changes. As the sediment in the central Arctic Ocean is mostly transported by iceberg and sea-ice, provenance studies can be used to infer the ice-sheet history and the surface circulation pattern. Bulk mineral assemblages are one of the proxies that can be used to identify the source areas of the Arctic sediments. The main aim of this thesis is to study in detail the quantitative X-Ray Diffraction (qXRD) software package RockJock which is used to obtain the bulk mineral assemblages result and the comparison of the two qXRD software packages RockJock and QUAX. In Chapter 4, three different sets of artificial mixtures are used to access the accuracy of RockJock, and the possible sources of errors are proposed. The comparison of RockJock and QUAX is based on the surface sediment samples retrieved from the Siberian shelf seas as well as the central Arctic Ocean. Quartz, feldspars, calcite, dolomite, and the sum of clay minerals show fairly good correlations, while the differences of individual clay minerals are high. In Chapter 5, surface sediment samples, which are used in Chapter 4, were analyzed using RockJock to test the possibility to use bulk mineral assemblages as provenance indicator. It shows that the combination of quartz, Qz/Fsp, dolomite and kaolinite can be used to identify source areas. Sediment input from the Canadian Arctic is generally characterized by high dolomite and Qz/Fsp values. Sediment input from the Eurasian Arctic shelf seas is generally characterized by low dolomite, Qz/Fsp, kaolinite values and high quartz values. Although the contents of amphibole are mostly too small to be quantified, the occurrence of amphibole might be an indicator of sediments from the Siberian shelf seas. In Chapter 6, three sediment cores selected from a transect across the Mendeleev Ridge were used in this thesis to study the provenance of terrigenous sediments from the Central Arctic in order to study the ice sheet history. It shows that the provenance of sediments deposited on the Makarov Basin side of the Mendeleev Ridge is different from that deposited on the Canada Basin side of the Mendeleev Ridge. The IRD events of MIS16, 12, 10, 8 are characterized by high dolomite contents, high quartz/feldspar ratios and low plagioclase contents and may suggest IRD input from the Canadian Archipelago. The IRD events that occur in MIS6, are characterized by high quartz and low dolomite contents, which indicates IRD from the Eurasian sources