建平地区三座庙序列侵入岩侵位机制讨论

ON THE EMPLACEMENT MECHANISM OF INTRUSIVE ROCKS IN SANZHUOMIAO SEQUENCE, JIANPING AREA

通过野外对三座庙序列侵入岩的岩体平面与剖面形态、岩体的内部构造、岩石与围岩的构造型式、接触带的度形特征等宏观地质特征的研究,推测岩体侵入位机制为强力挤入方式定位,即气球膨张式。笔者运用岩石的有限应变测量原理和方法,结合岩组分析及流变学、现代变形理论,对三座庙序列的侵入岩岩石做了有限应变测量和岩组分析工作,所得定量资料为确定岩体的浸位机制提供了理论依据。三种岩石有限应变测量,即:算术平均法、长短轴法、Rf/φ曲线法的富林指数k值均在0<k<1区间,应变型式属整体压扁型。显微矿物变形分析表明,矿物受到压性应力作用,进而判断岩体侵位机制为气球膨胀式。这种定性分析与定量测量分析相结合的研究成果所得结论是可信的。

Field studies on the macro-geological characteristics, which are the rock-body form on plane and section; the internal structures of the rock bodies; structural pattern of the rocks and its country rocks; deformed features of contact zones, indicate that the emplacement mechanism is to be strongly squeezing or balloon expansion-style location. The quantitative data of finite-strain measuring and the petrofabric analysing on the intrusive rocks provide the theoretical basis for discussing the emplacement mechanism. The Flinn exponent k of three finite-strain measuring methods: arithmetic mean method, majorand minor-axis method and Rf/ψ curve method are all in the range from 0 to 1. The strain pattern is of bulk flattening type. The analysis on the deformation of micro-minerals show that the minerals are subjected to compression stress, so the emplacement mechanism of the rock body is inferred to be balloon expansion type. The conclusion obtained from the qualitative analysis and quantitatively measuring analysis is reliable.