川滇交界东部地区汤家坪跨断层形变异常调查
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摘要
2011年以来,四川宁南汤家坪场地出现加速变化重大异常,为此中国地震局组成异常落实工作组开展现场落实,现场调查研究表明:(1)汤家坪场地观测点跨过次级断层,从破碎带中出现的石林现象,其物质组成不是第四系地层,石林陡立变形,方向性较好,与次级断裂的走向一致,应为构造岩受到挤压后变形的结果;(2)汤家坪观测场地各观测点位是稳定的。A点位于次级断层的南西盘上,从地质剖面图看出,桩基础为二迭系下统(P1)石灰岩、页岩、砂岩地层,基岩向下是有根的,整体基础是稳定的;B、C点均位于次级断层的北东盘上,沿公路边位置布置,基础部分是稳定的;(3)根据汤家坪场地1991年以来观测到的短水准、短基线曲线分析,观测结果没有明显的年变或非构造变形现象的干扰,反映了该场地跨越次级断层构造变形的实际变化,场地监测反映了次级断层的构造活动;(4)汤家坪场地A-B和A-C短基线、短水准的近期突出变化主要反映了跨越的次级断层的新活动。
The quick changes of fault slip in the fault-crossing deformation measurement of Tangjiaping site have appeared since 2011.A special term from several unites of CEA went to the field in order to investigate these abnormal changes.Our careful study shows following 4 possible conclusions:(1) the measurement points of site are located in both sides of sub-fault in Tangjiaping.In other words,from field investigation,the measurement site crosses a sub-fault and the geological structure around the observation site are caused by the compressing stress;(2) The point A is located in south-west footwall and has a steady basement with rock of limestone,shale and sandstone of Permian.The point B and C are located in the north-eastern side of the fault and by the side of a road and the basement of the points is stable as well;(3) According to the analyzing the observation data of short leveling and baseline carried out in Tangjiaping since 1991,the layout of the measurement site crosses the fault and the quick abnormal changes of measurement are caused by the activity of this sub-fault.(4) The observation data change of baseline and leveling measurement between A and B,A and C result from the tectonic activity of this sub-fault.
The quick changes of fault slip in the fault-crossing deformation measurement of Tangjiaping site have appeared since 2011.A special term from several unites of CEA went to the field in order to investigate these abnormal changes.Our careful study shows following 4 possible conclusions:(1) the measurement points of site are located in both sides of sub-fault in Tangjiaping.In other words,from field investigation,the measurement site crosses a sub-fault and the geological structure around the observation site are caused by the compressing stress;(2) The point A is located in south-west footwall and has a steady basement with rock of limestone,shale and sandstone of Permian.The point B and C are located in the north-eastern side of the fault and by the side of a road and the basement of the points is stable as well;(3) According to the analyzing the observation data of short leveling and baseline carried out in Tangjiaping since 1991,the layout of the measurement site crosses the fault and the quick abnormal changes of measurement are caused by the activity of this sub-fault.(4) The observation data change of baseline and leveling measurement between A and B,A and C result from the tectonic activity of this sub-fault.
引文
[1]四川省地质局第一区域地质测量队.中华人民共和国区域地质测量报告(米易幅,1:20万).
[2]程式,钱洪,杨永林,朱文庆.宁南汤家坪地壳形变异常的调查研究[J].四川地震,2003,(3):12-16.
[2]程式,钱洪,杨永林,朱文庆.宁南汤家坪地壳形变异常的调查研究[J].四川地震,2003,(3):12-16.