铜陵凤凰山岩体接触带构造变形特征

CHARACTERISTICS OF CONTACT STRUCTURAL DEFORMATION OF FENGHUANGSHAN PLUTON IN TONGLING, ANHUI PROVINCE

通过对凤凰山岩体接触带的变质与变形特征、显微构造及变形缩短量的计算 ,分析了凤凰山岩体侵位与接触带变形及区域变形的关系。通过接触带变质矿物变形特征的研究 ,揭示了热变质作用与侵位变形的同时性 ;接触带构造变形研究表明 ,岩体周围发育的流变褶皱、韧性剪切带、压溶缝合线等与岩体左旋上升与汽球膨胀侵位有关 ;围岩缩短量的计算结果表明 ,岩体侵位过程造成强烈的围岩缩短是一种强力侵位机制。研究表明 ,凤凰山岩体侵位是在区域NNE向水平左旋剪切应力场作用下完成的。岩体接触带变形是NNE向水平左旋剪切应力与横向推挤的侵位应力联合作用下形成的。

By studying the metamorphic and deformational characteristics, the microstructures, the rock fabrics and the shortening value of contact zone around Fenghuangshan pluton, this paper analyses the relationship between the deformation of contact zone,the regional deformation and the emplacement structural deformation. The research of deformation of metamorphic minerals around contact zone indicates the synchroneity of thermal metamorphism and deformation. The structural analysis suggests that the rheomorphic fold, the shear zone and the pressolved suture are caused by the ascent and emplacement of pluton. The shortening value of country rock presents forceful intrusion mechanism of Fenghuangshan pluton. It is indicated that the contact zone deformation of Fenghuangshan pluton is caused by the coalescing action of regional horizontal sinistral shear stress and lateral emplacement stress of pluton. It is suggested that the emplacement mechanism of Fenghuangshan pluton is the syntectonic ballooning.