| 四川龙门山构造带活动的钟乳石记录 |
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| 关键词:Longmenshan, Sichuan stalactite axis deflection tectonic activity |
| 基金项目:科技部科技支撑计划项目“地震断裂带的应力环境、应变能的分布及其与地震关系”课题(编号: WFSD-007)和中国地质调查局地质调查项目“青藏高原气候变化湖泊沉积记录研究”(编号: 12120113006100) |
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| Activity of the Longmenshan Tectonic Belt in Sichuan: Evidence from Stalactite Record |
| In the Longmenshan structural geology survey within Sichuan Province, the authors found a large number of limestone and calcium cementation conglomerate karst caves along the Longmenshan tectonic belt, which are closely related to the tectonic belt distribution, with some occurring directly in the fault zone. Different from caves in other areas, the stalactites developed at the top of the caves generally assume deflection phenomenon, i.e., the growth direction of the bottom of the stalactite is consistent with the vertical direction; however, the axis of the middle and top part of the stalagmite obviously shows a certain angle deflection in comparison with the vertical direction. These findings provide valuable actual materials for the study of Longmenshan structure activity characterized by the fact that the cave stalactites and stalagmite’s development show obvious deflection and switch caused by fault activities along the Longmenshan tectonic belt. The axis deflection of the stalactite and the AMS14C dating show that the Longmenshan tectonic belt is obviously characterized by cyclical activity. Previous dating revealed that the Longmenshan tectonic belt was in the period of tectonic activity at 21.81 ka (22.85 ka) and 19.3 ka (20.71 ka), which illustrates the structural episodes and cyclic active characteristics whose intervals or spans were 2.14~2.5 ka. The stalactite’s growth process in combination with seismic analysis reveals that the axis deflection resulted from the sustainable activities of Longmenshan tectonic belt in the period when deflection interface happened and during the fault activity period, and the activities led to a series of associated earthquakes in this period of structural activities. |
| SHAO Zhao-gang,MENG Xian-gang,HAN Jian-en,WANG Jin,YU Jia,HE Cheng-guang,QUAN Kai,CHEN Qi-guang.2014.Activity of the Longmenshan Tectonic Belt in Sichuan: Evidence from Stalactite Record[J].Acta Geoscientica Sinica,35(1):25-30. |
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