新疆诺尔特地区岩浆岩形成的构造环境及其意义

TECTONIC SETTING OF MAGMATITE FORMATION IN NURT AREA AND ITS SIGNIFICANCE,XINJIANG

诺尔特地区位于阿尔泰北部山区,西伯利亚板块西南缘。花岗岩广泛分布,主要为加里东晚期、华力西中、晚期花岗岩,存在燕山期花岗岩。区内火山岩主要是泥盆纪及石炭纪火山岩,泥盆纪火山岩赋存于上泥盆统忙代恰组中,石炭纪火山岩赋存于下石炭统红山嘴组中,主要为中-酸性火山岩,属钙碱性系列。区内岩浆岩构造环境的研究表明,加里东晚期花岗岩形成于汇聚阶段,属挤压环境;华力西中期花岗岩形成于新陆壳阶段弛张期向活化期过渡的时期,应力体制由拉张向挤压过渡;华力西晚期花岗岩形成于新陆壳阶段活化期,属挤压环境;燕山期花岗岩形成于古生代新陆壳在中生代的发展阶段,属挤压环境;泥盆纪火山岩是新陆壳发展阶段固结期的产物,石炭纪火山岩为弛张期及活化期演化过程中的产物。

The Nurt area is located in the north o f Altay,at the southwest of the Siberia plate.The granites were formed at late Caledonian epoch,middle Hercynian epoch and late Hercynian epoch are widely exposed and some formed at Yanshanian epoch i n the Nurt area.The volcanic rocks are mainly Devonian and Car-boniferous volcanic rocks.The Devo nian volcanic rocks occur in the Upper Devonian Mangdaiqia Formation and the Carboniferous volcanic rock s occur in Lower Carboniferous Hongshanzui Formation.The volcanic rocks are intermediate and acidic ro cks,and belong to calcium-alkalesc ence series.The study of tectonic setting shows that the granites of la te Caledonian epoch were formed at th e convergent phase and the com-pressive setting,the granites of mi ddle Hercynian stage were formed at t he stage from the relaxation stage to the mobilization stage of new contin ental crust phase and the crustal str ess was changed from tensile stress t o compressive stress,the granites of late Hercynian stage were formed at t he mobilization stage of new conti-nental crust phase and the compressive setting,the granites of Yanshani an epoch were formed at the new continental crust of Mesozoic era an d the compressive setting.The Devon ian volcanic rocks were formed at the consolidation stage of a new cont inental crust phase,and the Carboni ferous volcanic rocks were formed at the stage from the relaxation stage t o the mobilization one of a new contin ental crust phase.