|
Diatoms is an important group of marine micropalaeontology ecological distribution and physical and chemical properties of the water, migration, and closely related to water nutrition. Fossil diatoms in sediments implies a large number of ancient marine environment and paleoclimate information, can provide valuable information for global environmental change and climate processes, as well as warm movement plays an important role in the study of ancient oceanography. This thesis is to Quaternary diatoms of the Okinawa Trough sedimentary samples (ie ODP195 voyage 1202B 60 column samples and the District of nine surface samples), analysis, identification and research-based combination foraminiferal oxygen isotope, AMS14C dating and other relevant information, analyze paleoenvironmental and paleogeographic changes in the area since 16ka year, explore ancient Kuroshio in the Okinawa Trough since the Last Glacial changes. The results show that: the basic characteristics of the surface distribution of diatom fossils: reduced along the Kuroshio flows to both sides, showing a low - high - low trend, that is, by the effect of the Kuroshio large area deposition diatom abundance and high by the the Kuroshio effect weak on both sides of the regional sedimentary diatom abundance is low. 2. 1202B Core core diatom species are more abundant, the study identified 81 species and varieties were analyzed and identified, belonging to 32 genera, but only 10 kinds of diatoms basic continuous distribution in the core, and more high content, as well as some of the round sieve alginic often appear, but the percentage content is not high, remaining species only sporadic detection, very low levels. Depending on the type of diatoms in the core content and diatom abundance variation bottom-up divided the three diatom assemblages, I combined with the output layer bit 61.7m to 81.9m, ie 14 000a to 16 000a, shallow littoral and shallow marine depositional environment environment, water environment, the main reason for its poor diatom lack of nutrient salts deposition environment, and by the effect of longshore currents and turbidite deposits, and not any of the Kuroshio The role of marine sedimentary record; II combination with stratigraphic horizon 31m ~ 61.7m, 500a to 14 000a, is a shallow water environment, water environment become darker. By Black's colder climate, and adequate nutrition salts, which with diatom fossils is very rich; the band with groove Melosira columnar Cyclotella the higher levels, and fewer species of tropical ocean tide of weak effect; the Ⅲ combination with stratigraphic horizon between 0 ~ 31m, that is, from 8500 to the present, bathyal and deep-sea environment, rich diatom, overall diatom assemblages characteristic presented environmental characteristics similar to the modern environment, strong Kuroshio effect Kuroshio sedimentary record through the stations.
|