冲绳海槽晚更新世以来沉积速率的时空差异及其控制因素

SPATIAL AND TEMPORAL VARIATION OF THE SEDIMENTATION RATES IN OKINAWA TROUGH SINCE THE LATE PLEISTOCENE AND THEIR CONTROLLING FACTORS

收集和分析了冲绳海槽内不同区域的33个站位柱状样的测年资料,计算了不同时段的沉积速率。结果表明,冲绳海槽内晚更新世以来的沉积速率有较大的时空差异,在空间上,由北向南有沉积速率增加的趋势,而靠近海槽西坡的站位沉积速率要大于东坡;在时间上,晚更新世期间的沉积速率要明显大于全新世。冲绳海槽内不同区域和不同时段沉积速率的差异反映了海槽内沉积环境和物质来源的复杂性,这种差异性主要是由不同区域沉积作用和物源供应变化的结果引起,末次冰消期以来的古海洋环境的变化、黑潮的摆动等因素也起到一定的作用,而事件沉积(如火山—热液作用和浊流沉积)的影响也不容忽视。

By using the collected chronological data of 33 sediment cores from Okinawa Trough,the sedimentation rates（SR） in different chronological sections of these cores were calculated.The results show very large spatial-temporal variations of the sedimentation rates in the trough.Spatially,there is an increasing trend of the SR from the north to the south,and the SR is much larger in the western slope of the trough than that in the eastern slope.Temporally,the SR increased greatly from late Pleistocene to Holocene.Owing to the result that the sediment in the trough was mainly composed of the terrigenous detritus,we suggest that the variability of the SRs in different parts and different chronological sections in the Okinawa Trough just reflected the complexity of the sedimentation environment and material origins,and mainly resulted from the variation of the sedimentation processes and sediment budget in different sites and ages.Meanwhile,the paleoceanological changes,the shifts of the Kuroshio Currents since the last deglaciation in this area also played an important role in this variation of the SRs.However,the event sedimentation,such as the volcanic event,and turbidites can also take great effect on the sediment accumulation in Okinawa Trough,thus,the effect of event sedimentation could not be less-estimated.