KMS Institute of Mountain Hazards and Environment,CAS
|Alternative Title||THE RECENT PROGRESS OF NEOTECTONIC RESEARCH IN PANZHIHUA-XICHANG REGION|
攀西地区(攀枝花-西昌地区的简称)处于青藏高原东南部的边缘地带，属横断山系东部北段的雅窘江下游流域，并跨越金沙江与大渡河流域的一部分。20世纪40 年代提出的前寒武纪“康滇地轴”与70 年代提出的中生代“攀枝花－西昌裂谷带”即指该区。它是我国西南部的一个重要地质构造单元，控制着中国南部东西两大构造域的发展。在晚新生代，该区又随着青藏高原的隆起，成为横断山系块断带这一新大地构造单元的重要成分。该区是发展中的综合冶金工业基地，其新构造问题，就不仅是涉及古裂谷封闭后的演化与横断山系形成的学术问题，更是直接关系地质灾害危险区划与大型建设项目的工程地质评价的基础地质问题。有关这一问题的基本资料，笔者等已在“雅若江下游新构造研究报告”(1983.12) 和《攀西地区新构造》(1988) 作了总结。本文根据近年的若干新资料，就新构造期的下限、李明久－桐子林断裂带的活动性与新构造运动的灾害地质效应作补充论证。
The paper has discussed problems as follows:
the geological hazards and neotectonic controlling to the hazards. Xigeda Formation of the lower Pleistocene are unconformably overlying on the Eogene or pre-Cenozoic in the southwest of Sichuan. The paleocrust of weathering of laterite type (panzhihua Red Earth) was developed along the unconformity. The paleocrust of weathering which belongs to Pliocene is a buried paleoplanation surface. Panzhihua Red Earth existed in widely area indicates a paleoplanation period corresponding Gilbert epoch of paleomagnetic chronological scale. Xigeda Formation was deposited in graben basin which came iQto being by block - movement after paleoplanation period. In other words , the period of paleoplanation is the neoteconic period corresponding the Gauss-Brunhes epoch.
The deformation of Quaternary and landforms of neotectonis show there were five activities in Limingjiu faults during the neotectonic period , three times since the upper Pleistocene and the last one was during the middle Holocene. Two epicentres (M=5. 5) located at the faults show that it is a earthquake faults. The faults divided into two branches of east fault and west fault through the only candidate dam area of TongziIin hydroelectric station. By data of vertical ground deformation measurement , the rate of 1 mm/y for the west fault (through the right dam shoulder) and 3. 02 mm/y for the east fault (through the left dam shoulder outside 400 m) , the recent activity of the faults is confirmed. For the dam of Tongzilin hydroelectric station is located on the active faults , author resuggest to give up building the dam here.
Hengduan Mountain System concl uded the region of Panzhihua-Xichang region belongs to orogenic zone of neotectonics. The geological hazards , such as earthquakes , faillings, landslides and debris f1ows , are not only high intensity but also high frequency. The pattern of geological hazards is controlled by neotectonis. The distribution and intensity of geological hazards and geological conditions of gravitational hazards are also controlled by neotectonics. The Hengduan Mountain System is uplifting now. It is premise of geological hazards division and calculation to know this controlling effcts.
|陈富斌. 攀西地区新构造分析. 横断山系新构造研究. 成都:成都地图出版社,1992:46-55.|
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