冲绳海槽中部距今近70ka以来的孢粉记录及物源探讨

研究钻孔DGKS-9602位于冲绳海槽中部,岩芯长度为931 cm,钻孔年代覆盖了氧同位素1～4阶段,年代可追溯至距今73 ka.孢粉分析结果证明,孢粉带与氧同位素阶段有较好的对应关系,其中松属花粉与蒿属花粉比值(P/A)与海平面变化曲线相互吻合.应用非相似性类比法将钻孔孢粉样品与陆地表土孢粉样品进行欧氏距离计算,从而...

Pollen records from the middle Okinawa Trough and the terrigenous pollen source analysis for 70 ka BP

Core DGKS-9602 is located in the middle Okinawa Through.The total length of the core is 931 cm and 88 samples were collected from the core.the core age appears to cover marine isotope stages (MIS) 1~4, with the oldest age at upproximatedly 73 ka BP. A pollen analysis from the core indicates that there is a strong relationship between pollen zones and oxgyen isotope stages.The curve of ratio between Pinus and Artemisia (P/A) is concordance with sea-level change of the region. Fossil pollen and modern surface pollen were used to calculate the Euclidean distance by non-similarity analogy and to estimate the pollen source areas, which made it possible for further study on the changes of the terrigenous matter source regions under different sea-level conditions.The results show that during MIS 4 the main source of pollen is the north region of the Okinawa Through, which is dominated by coniferous forest. At the MIS 3 stage, the sea-level is relatively high, and the eastern China (the Middle and Lower Changjiang River) and Kyushu may be the main source areas during this period where the mountain conifers mix with some broad-leaved plants dominated the forests.During MIS 2, the sea level declined dramatically, that is 'coincided with P/A ratio by dropping sharply to <1.The pollen analogue study shows that the pollen grains at last glacial maximum (MIS 2) may be mostly derived from the vicinal continental shelf plains in a short transport distance where the vegetation is predominated by grassland and wetland.Regarding to the Holocene, the result indicates a wide and diverse source areas, including the Changjiang River and the Huanghe River in China, as well as the water current of Kuroshio flowing from tropical regions.