麻粒岩区构造地质编图原则探讨

ON THE PRINCIPLES FOR COMPILATION OF TECTONIC MAPS OF GRANULITE TERRANES

麻粒岩区的边界及亚区划分标志常为等变线、断层或剪切带。主要地质单元包括灰色片麻岩、花岗片麻岩、混合岩、副变质表壳岩、层状侵入体、高级变质绿岩等，基性岩墙群为划分不同地质单元、建立其相对时序的重要标志。以上单元普遍被构造叠置，常可识别出侵入关系。表壳岩系底部不整合及地层层序的研究对于认识大陆克拉通化过程及沉积环境演化具有重要意义。早期大规模水平构造先后被两类变形序列叠加，第Ⅰ类与麻粒岩相变质发生于同一构造事件，第Ⅱ类与麻粒岩相变质无关，系晚期构造变形；麻粒岩区的构造样式取决于以上构造变形序列的相对影响程度。

The granulite terranes are often confined by prograde and retrograde isograde,faults or shear zones,which are also used to divide subprovinces.The main geological units composed of granulite terranes include grey gneiss,granitic gneiss,migmatite,supracrustal rocks,mafic to ultramafic layered intrusion and equivalents of greenstone,with which mafic dyke swarms are useful for division and establishment of relative sequence.The different units were widely tectonically interleaved and stacked,obscurring the early intrtisive contacts,unconformity,and stratigraphic sequence of supracrustal rocks.It is necessary to reconstruct the early tectonic relations for understanding the continental cratonization and the evolution of sedimentary setting.The early deformation of granulite terranes often involved the large-scale horizontal tectonics,superimposed by the late typeⅠdeformation series accompanied by granulite-facies metamorphism of the same tectonic event,and type Ⅱ resulting from the post-metamorphism tectonic events.Therefore.tectonic patterns in granulite terranes were dependent upon superposition of different deformation series.