阿尔泰额尔齐斯构造带岩石应变特征及其构造意义

阿尔泰额尔齐斯构造带东段岩石变形强烈,最大应变椭球轴比(Rxz)可达10～30,剪应变(γ)达4～6。该带可分为2个层次4个次级构造带。第一层次为韧性—韧脆性中—中-浅层次变形带,包括萨尔布拉克—科克萨依脆性挤压劈理化带、达拉维孜—阿热勒托别剪切流变构造带和库尔提—玛因鄂博韧性剪压变形带,第二层次是齐伯度—富蕴深层次超韧性变晶糜棱岩带。第一层次变形带中沿达拉维孜—阿热勒托别一线为最强变形带,向两侧依次减弱。中心带以剪切—拉伸变形为主,两侧以压扁变形为主兼有剪切,均为左行剪切。结合区域地质分析,可认为这3个变形带共同组成一个完整的板块(微陆块)聚合变形带,显示喀拉通克岛弧以北东偏东方向俯冲于可可托海—青河陆缘岩浆弧之下,并发生弧—陆碰撞。齐伯度—富蕴变晶糜棱岩带岩石变形温度压力条件高,以右行剪切为特点,具有完全不同的地质演化历史,反映它可能是在古生代期间被强烈改造的具有前震旦纪结晶基底的微大陆的残块(或断片)。

Rock strain characteristics and its regional structure significance in the eastern segment of the Ertix tectonic zone, Altay, Xinjiang

The largest strain ellipsoid axis ratio(Rxz)of the strongly deformed rocks in the eastern segment of the Ertix tectonic zone was 10～30,and the largest shear strain(γ)was 4～6.The tectonic zone could be divided into two deformation levels and four secondary structural deformation belts.The first deformational level consisted of three ductile to ductile-brittle meso-shallow deformation belts,namely,the Sa’erbulake-Kekesayi brittle compressive cleavage belt,the Dalaweizi-Areletebie shear rheomorphic belt and the Ku’erti-Mayin’ebo ductile shear-compressive belt from southwest to northeast.The strongest deformation occurred in the central belt(the Dalaweizi-Areletebie shear rheomorphic belt),and the deformation in the rocks became weaker and weaker from the centre to the both sides.Meanwhile,the strain was mainly left-lateral shear-stretch in the centre and mainly compressive with a little left-lateral shear in the both sides.These three ductile to ductile-brittle meso-shallow deformational belts made up a complete plate(micro-landmass)condensation zone,indicating that the Kalatongke island arc underthrust,towards northeast to east,the Keketuhai-Qinghe magmatic arc,then a continent-arc collision occurred.The second deformational level was Xibet-Fuyun meso-deep level crystalloblast mylonite belt,formed at a condition of higher temperature and pressure.The strain was mainly right-lateral shear in the belt.It was suggested that the Xibet-Fuyun belt was a relict block(or a thin faulted piece)of a micro-landmass with pre-Sinian crystalline basement reformed strongly in Paleozoic,so its evolutional history was obviously different from the other three structural belts mentioned-above.