STRAIN ANALYSIS OF ROCKS IN THE LANSANG WATERFALL, CHANGWAT TAK, THAILAND

The objectives of this research are to quantify the finite strain of rocks and describe the deformation history of rocks in area of Lansang Waterfall, Tak Thailand where located within the Mae Ping shear zone; an affected area of past India- Asia penetration. By this process the structural geology on this area was accumulated strain inside and responded it in form of deformation. This research quantified the finite strain of rocks on this affected area from deformed minerals and a quantity of finite strain can be described by strain ellipsoid of rock followed by Fry’s method (Fry, 1979).From the strain quantitative analysis of rocks from deformed minerals in area of Lansang Waterfall, Tak Thailand follwed by Fry’s method (Fry, 1979) found that from all 13 rock sample locations, the averaged finite strain ratio of rocks and the angle- value between the longest axes of strain ellipsoid and the deformation boundary ranged between 1.35 to 1.69 and 22°to 41°, respectively. The shape of strain ellipsoid and the relative between that value intense the deformation process that applied and lead structural geology accumulated strain inside and finally deformed which the process of left- lateral simple shear applied on this area on the direction of NW- SE and lead deformation occurred on of Lansang Waterfall, Tak Thailand during the Eocene. Moreover, when compared the result of this research with the further work found that they are corroborated and related to each other.

本研究的目标为量化泰国达府兰桑瀑布区域（该区域位于古印度-亚洲板块碰撞作用影响的湄平剪切带（Mae Ping shear zone）内）的岩石有限应变，并阐明区域岩石的变形演化历史。区域内的构造地质体通过内部应变累积，并以变形的形式体现其对构造作用的响应。本研究依托变形矿物对该受影响区域的岩石有限应变进行量化，有限应变量可通过Fry方法（Fry, 1979）结合岩石应变椭球进行表征。通过采用Fry方法（Fry, 1979）对泰国达府兰桑瀑布区域变形矿物对应的岩石开展应变定量分析，本研究得到如下结果：在全部13个岩石采样点位中，岩石的平均有限应变比，以及应变椭球最长轴与变形边界的夹角分别介于1.35~1.69与22°~41°之间。应变椭球的形态与上述参数的相对关系，可反映研究区所经历的变形作用过程：区域内构造地质体先发生内部应变累积，最终发生变形；该区域在始新世时期遭受北西-南东向的左行简单剪切作用，最终引发兰桑瀑布区域的变形现象。此外，将本研究结果与后续相关研究成果进行对比后发现，二者相互印证且具有内在关联性。