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对福州盆地鳌峰洲残留沼泽沉积540 cm的FZ1钻孔进行了元素地球化学和137Cs以及加速器碳同位素(AMS14C)测年。结果表明:钻孔存在2段不同的沉积环境,下部为洪冲积,上部为沼泽沉积,然而2段各自的沉积环境则相当稳定。137Cs测试在沼泽相稳定沉积出现的3个蓄积峰与北半球的放射性年代标尺可以对比。根据蓄积峰年代和插值后获得的钻孔底部年龄约为公元1950年,与钻孔底部的AMS14C测年基本吻合,该结果表明采用137Cs测年方法定年是可行的。沉积速率研究揭示:20世纪50年代初至60年代中,近代洪冲积在福州盆地断块下沉区沉积速率极快,钻孔下部粉砂质淤泥的沉积速率达到20.9 cm/a;随着闽江下游盆地平原与河流变迁以及心滩的形成,原来的水道快速淤积演变为陆地沼泽环境,沉积速率开始逐步减小:20世纪60―70年代中降为9.9cm/a,70―80年代中继续下降为7.1 cm/a,80年代中之后降为3.1 cm/a。福州盆地中心区的高沉积速率与全新世断块差异性活动存在着密切关系。
Elemental geochemistry and 137Cs and Accelerated Carbon Isotope (AMS14C) dating of 540 cm FZ1 boreholes in the residual marsh of Aofeng Basin in Fuzhou Basin were conducted. The results show that there are two different depositional environments in the boreholes, the lower part is flood alluvial and the upper part is swamp deposition, however, the sedimentary environment of each section is quite stable. The 137Cs test can be compared with the radioactive dating scale in the northern hemisphere for the three accumulation peaks that appear in the swamp stable deposition. According to the accumulation peak age and interpolated bottom drilling age obtained about the year 1950, and the bottom of the drill AMS14C dating roughly consistent with the results show that 137Cs dating dating method is feasible. Sedimentation rate studies revealed that during the early 1950s and 1960s, the depositional rate of the modern flood alluvial deposits in the subsidence area of the Fuzhou basin was extremely high, and the deposition rate of silt in the lower part of the borehole reached 20.9 cm / a. In the lower reaches of the river basin, the plains and rivers changed and the heart-beach formed. The original sedimentation quickly changed into a land swamp environment and the sedimentation rate gradually decreased. From the 1960s to the 1970s, the sedimentation rate dropped to 9.9 cm / a. From 1970s to the 1980s Continued to decline to 7.1 cm / a and dropped to 3.1 cm / a after the mid-1980s. The high sedimentation rate in the central area of Fuzhou basin is closely related to the difference activity of block faults in the Holocene.