控制碰撞造山带热异常形成的主要因素及其地质作用分析

本文对剥蚀、逆冲断层剪切摩擦和放射性物质富集等因素对造山带热结构和热演化的影响进行了模拟计算以及定量分析,并对热异常与造山带内的若干地质现象之间的关系进行了讨论.在剪切生热模型的计算中考虑了逆冲断层的速度变化及其对热结构的影响,考察了断裂宽度与热结构之间的关系.计算中还考虑了两种热剪切计算模式,即:(1)瞬间推覆就位模式;(2)非瞬间推覆就位模式.从计算与讨论中得出如下认识:造山带后期的剥蚀使整个岩石层加热;剪切摩擦使壳内局部地区升温;放射性物质的富集主要使上部岩石层产生热异常.三者联合作用的结果使岩石层大幅度升温,从而形成造山带内部大范围的与其它地区不同的高温异常以及独特的地质特征.通过计算和讨论,文中认为:重熔型花岗岩和大量的构造岩是造山带内逆断层剪切作用的产物;与逆断层呈平行排列的拉张正断层是造山带在诸因素作用下升温,然后又经剥蚀,物质发生热收缩的结果.在造山带演化后期出现的这种拉张正断层代表造山带解体和向盆地转化的构造面貌.

THE ANALYSIS TO BASAL FACTORS OF THERMAL ANOMALY GENERATION AND ITS GEOLOGICAL FUNCTIONS

The effects of erosion, fault shear rub and radioactive element concentration on the thermal construction and evolution have been modeled, and the relation between thermal anomalies and some geolagical events in orogenic belts has been analysed in the paper. The variation of thrust movement and its effects on geothermal construction have been considered in the modeling, and the relation between the width of faults and the thermal construction in thrust belts is obtained. Auther consideres two models for shear heating: the instantaneous thrust locating model and un-instantaneous thrust locating model. The results are as follows: the erosion of orogenic belts in its post stage heats the crust, thd shear rub warms the local regiones, the concentration of radioactive elements produces thermal anomalies in up-lithosphere. The combination of the geological factors makes the temperature of lithosphere increase and it results in high temperature anomalies and special geological characteristics in wide area of orogenic belt which differ from some other geological regions. Author suggests that the large amount of S type granite and tectonite could be the products of thrust shear, the extension faults paralleled to the thrust faults could be the results of heated orogenic material contraction of cooling due to the erosion. The extension faults in post stages of orogenic developmer represent the tectonic features of orogenic disintegration and transformation to bains.