[关键词]
[摘要]
峨眉山为一断块山,因其宏伟、秀丽而著称,但峨眉断块山是如何形成的,缺乏系统深入的研究。论文基于1:25 000万工程地质测绘,较为系统地研究了峨眉山地质构造形迹及构造叠加特征,认为峨眉山抬升始于古近纪晚期,喜山运动第一幕(始新世中期末)峨眉山受青藏高原隆升的影响,在北西西-南东东向区域应力场作用下,形成北北东向褶皱及北东向断层,并上升成为剥蚀区;。上新世以来,在近东西向区域压应力场作用下,钝锥形大峨山断块沿北东向峨眉山断层及北缘的北西向边界断裂不断向东强力楔入,断块前缘早期的北北东向构造受推挤,地层走向及倾向出现明显偏转:锥顶前方龙门洞-报国寺一带地层由早期的北北东走向倾南东的中生代地层转为南北走向,地层出现倒转(西倾),而远离断块端部的地层仍然为正常产状;。与此同时,锥顶北侧尖尖石背斜发生移褶,形成北西向褶皱和断层;,而断块南侧峨眉山断层发生逆冲兼走滑活动。第四纪以来峨眉山间歇性强烈抬升,经历至少10次强烈抬升事件,逐渐形成现今地貌。新生代以来,峨眉山断层两盘地层水平位错累计达4 km,垂直位错累计达6 km
[Key word]
[Abstract]
The Mt. Emei is a faulty block mountain, it is famous for the great and beautiful, but how it was formed? There is no systematically studied. Based on the engineering mapping of 1:25000 scale, the paper systematically studies the geological structure feature and structural superimposed folds, some research results can be concluded: The uplift of Mt. Emei began in the end of the Eocene, i.e. , during the Himalayan movement of the first epoch, under the pressure of NWW-NEE regional geo-stress, the NNE strike folds and NE faults have been formed, it uplifted and became the erosion area. Since the Neocene, under the nearly EW regional pressure geo-stress field, the blunt cone Daeshan faulty block was wedging eastward, the early NNE strike strata of the block frontier bent anti-clockwise, the strike of the strata in the frontier area (Longmendong–Baoguosi ) became SN, the strata dip westward; the Jianjianshi anticline bending eastward in north boundary of the block, forming NW strike tectonic superposition, while the outer area far from the block frontier, the attitudes of the strata are normal; The Emeishan fault slips in east boundary, Since the Quaternary, The intensive intermittent uplift,10 uplifting events happened and the relief gradually formed. Since the Cenozoic, uplifting distance of the Emeishan fault is about 6000m, the strike slip distance is 4000m.
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[基金项目]
国家自然科学基金:深切河谷强震作用下谷坡地震动响应监测研究(41072231),中国地调局项目:“汶川地震地质灾害调查评价”-川西深切河谷斜坡地震动评价技术研究(1212010914010)