东秦岭早古生代两条不同构造—岩浆杂岩带的形成构造环境

东秦岭造山带早古生代（５００Ｍａ～４００Ｍａ）分别在北秦岭和南秦岭发育两条构造－岩浆杂岩带。北秦岭带由洋盆消减的火山杂岩和深成侵入杂岩组成，是活动陆缘挤压构造背景的产物；南秦岭带由辉长、辉绿岩体、岩脉，超浅成隐爆的碱基性－超基性火山岩和粗面岩组成，是被动陆缘拉张裂陷环境的产物。它们平行造山带走向分布，南、北对峙，构成时空有序的构造－岩浆杂岩带。其形成的构造机制整体上受旱古生代古秦岭洋盆沿商丹一线的俯冲和消减作用的控制，造成北部俯冲挤压，南部拉张裂陷，同时南部的拉张裂陷也受陆壳之下地幔热柱上涌的影响。

Tectonic Setting on the Two Different Tectonics-Magma Complex of the East Qinling in Early Paleozoic

There are two different Early Paleozoic (400Ma ~ 500Ma) tectono-magma complex belts in the North and South Qinling of the East Qinling orogenic belt. The North Qinling belt complex is composed of oceanic island--arc volcanics and intrusive complex bodies, being products of active margin under the compresive setting, whilst the South Qinling complex belt is characterized by gabbro plutons and diabase dikes, super--hypabyssal cryptoexplosion alkali basic--ultrabasic volcanics and trachytes, representing products of passive margin under extentional cracking setting. Both of them are parallel along the Qinling orogenic belt and confront each other from north to south, consisting of the tectono-magma complex belts in space and time in order. Their dynamics were controled by subduction process of ancient Qinling oceanic basin along Shangnan-Danfeng belt in Early Paleozoic, Which made the northern margin under subduction compression and the southern margin under drawing--out cracking. In addision,the extentional cracking of the south belt concerned closly with rising of hot mantle plume under crust.