建平地区太古宙变质杂岩构造变形及演化特征

TECTONIC DEFORMATION AND EVOLUTIONAL CHARACTERISTICS OF ARCHAEOZOIC METAMORPHIC COMPLEX FROM JIANPING AREA

建平地区太古宙变质岩石发育,地质构造复杂。近年研究表明:区内太古宙变质杂岩是由多期变质、变形的中酸性深成侵入岩和少量上壳岩组成,可划分出变质上壳岩组合、叶柏寿片麻岩、斜长片麻岩和二长片麻岩4个岩石单位。本文主要对区内太古宙变质杂岩的构造变形及构造演化进行讨论,初步确定了早期韧性变形阶段(鞍山期划分4个变形幕)和晚期脆性变形阶段(印支—燕山期)。构造层次由早期深部层次向晚期浅层演化;其变形由流动机制—压扁机制—弯曲机制—韧性剪切机制到剪切破裂机制的演化。

The Archaeozoic raetamorphic complex is well developed with complicated geological structures in Jianping area.The recent studies show that the metamorphic complex of Archaeozoic is composed of the metamorphic or deformed intermediate-acid plutonic intrusive rocks and a little supracrustal rocks.It can be divided into four units: metamorphic supracrustal rocks, Yebaisou-gneiss, plagioclase-gneiss and monzonitic gneiss. Based on the studies on the tectonic deformation and evolutional characteristic of the Archaeozic metamorphic complex in the area,the author believes that the complex is deformed in two stages, the early ductile and late brittle deformation.The tectonic level had evolved from early plutonic to late hypabyssal and deformation mechanism evolved from flow, flattening, buckling, ductile shear to shear rupture.