大别造山带中生代花岗岩类成分的时空分布与造山带演化的关系

RELATIONSHIP BETWEEN SPACE-TIME DISTRIBUTION OF MESOZOIC GRANITOID ROCKS AND EVOLUTION OF DABIE OROGEN

长江中下游及两侧的大别隆起带、扬子隆起带都是华北、扬子陆块中生代碰撞造山涉及的区域，它们可分成４个地块．对４个地块中中生代花岗岩类的区域地球化学研究，并结合其他方面资料的共同限定，证明它们都是两个陆块碰撞后（ｐｏｓｔｃｏｌｉｓｉｏｎ）区域岩石圈物质调整阶段的产物．各岩带的花岗岩类可归入早、晚两个阶段，分别具有１３７Ｍａ和１２３Ｍａ的峰值侵位年龄．早、晚阶段花岗岩类都具有Ｉ型花岗岩类的成分特征，晚阶段花岗岩类还具有Ａ型花岗岩类的成分性质；早、晚阶段花岗岩类之间具有不连续的成分演化关系．它们指示，本区早、晚阶段花岗岩类的形成是两陆块中生代碰撞后发生的两次有一定联系但又独立的岩石圈热－构造事件的产物．

The area of Dabie and the lower-middle reaches of the Changjiang River, the collision regions of North China Craton and Yangtze Craton in Mesozoic Era, can be divided into four blocks. The systematic geochemistry researches of the Mesozoic granitoid rocks in the four blocks, combined with other data, demonstrated that the granites were produced by the material adjustment of the regional lithosphere after the collision. Every lithizone can be divided into two stages, early and late, with 137Ma and 123Ma peak values of intrusion age. The former has the features of I-type granitoids and the latter has the nature of I-type and A-type granitoids. There are no continuous component evolution trend between the granitoids of early and late stages. There features indicate that the two stage granitoids were the results of two thermo-tectonic events in the continental lithosphere after the collision, and the two thermo-tectonic events could bave been associative and also independent.