The Sediment Flux of the Longmen Shan Foreland Basin During the Late Triassic Epoch and the Uplift and Denudation of the Orogenic Belt
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摘要: 根据钻井资料、地层剖面资料,利用Surfer8.0软件编制出晚三叠世前陆盆地各组段的残留地层等厚图,得出各组段残留地层的沉积总量,并计算出各阶段沉积通量:21.4 t/(m2·Ma)、184.2 t/(m2·Ma)、278.0 t/(m2·Ma)、147.6 t/(m2·Ma)、703.5 t/(m2·Ma)、272.0 t/(m2·Ma)。然后,利用物质平衡法将沉积物回剥至龙门山造山带并进行脱压校正,计算出晚三叠世龙门山造山带剥蚀总厚度为2 514 m,各阶段造山带剥蚀速率分别为:0.009 mm/a、0.114 mm/a、0.133 mm/a、0.094 mm/a、0.423 mm/a和0.133 mm/a。最终,重塑了龙门山造山带晚三叠世的隆升历史:在距今228.0~199.6 Ma的时间内龙门山造山带地壳隆升了约4.3~4.6 km,地表隆升了1.8~2.1 km;并且隆升过程具有明显的阶段性,可划分为初始隆升(228.0~216.5 Ma)、加速隆升(216.5~211.0 Ma)、缓慢隆升(211.0~203.6 Ma)、急剧隆升(203.6~202.7 Ma)和缓慢隆升(202.7~199.6 Ma)五个阶段。Abstract: Based on boreholes and stratigraphic sections, we draw maps about uniformly thick residual formation in the Longmen Shan Foreland Basin with Surfer 8.0 software, work out the total amount of sediment of residual formation, and figure out the sediment flux in each phase: 21.4t/(m2·Ma),184.2t/(m2·Ma),278.0t/(m2·Ma), 147.6t/(m2·Ma),703.5t/(m2·Ma), and 272.0t/(m2·Ma). Then we denude back the sediment to the orogenic belt based on material balance method and carry out depressure correction. We can work out the aggregate thickness denuded is about 2 514 m on Longmen Shan during the late Triassic Epoch, and the speeds of denudation in each phase are: 0.009 mm/a,0.114 mm/a,0.13
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Key words:
- sediment flux
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