Distribution Of Carbonate In Sediments And The Paleo-oceanographic Significance Of Carbonate In The West Arctic Ocean

Arctic area as a driver and adjustor of global climate, it reflects sensitively to climatic change. It will be significant to do paleo-oceanographic research in Arctic, which could be very helpful to the prediction of future global climate change. Carbonate content is a mature and effective index for paleo-oceanography, but carbonate contents are commonly low in Arctic and so the study value is rebated largely. So the main aim of this thesis is to identify how much the paleo-oceanographic value of carbonate index is in the West Arctic Ocean. I used volumetric method to get carbonate contents of samples, and cited the age frames of cores from advisor Gao. This thesis mainly discussed distribution of carbonate contents, dissolution and deposit of carbonate, including analysis of carbonate compensating depth, paleoclimate and paleoproductivity analysis of carbonate. I concluded the following results:⑴The carbonate content of surface sediments are widely low, with a range from 0.22% to 13.22%, and average is 3.48%, but the high content only appear in several surface sediments at about 2000m water depth area. The carbonate content of surface sediments have a significantly correlation with water depth;⑵Carbonate content along vertical are generally low, but several peak values appear among generally low background;⑶Carbonate accumulation speed at C9 and R11 vary between 0.008g·cm-2·a-1 to 0.016g·cm-2·a-1 and 0.009g·cm-2·a-1 ~ 0.017g·cm-2·a-1 from 5 meter behind surface, respectively;⑷The lysocline is 1800m~2000m and the CCD in study area is about 3500m, according to the fitting curve between carbonate content at all surface sediment samples and water depths;⑸Peak values of carbonate content generally appear at alternant periods of oxygen isotope, but there are some exceptions. The peak value in MIS6 is especially distinct. I presume a inferior warming event occurred. The fluctuation of carbonate content curve don't reflect harmoniously with glacial-interglacial, so the paleo-oceanographic value of carbonate index is not significant in the West Arctic Ocean;⑹Because severe dissolution of carbonate and restraint from siliceous life matter exist in Chukchi study area, layers of peak carbonate content may indicate high paleoproductivity.