北秦岭老君山环斑花岗岩的成因及大地构造意义

老君山环斑花岗岩分布于北秦岭造山带中，是沙河湾、朱厂沟脑、秦岭梁北秦岭环斑花岗岩带的一部分，以特殊的环斑结构，富含基性暗色微粒包体为特征，通过对其地质、岩石、地化资料研究，结合区域大地构造环境，认为老君山环斑花岗岩，具有岩浆混合成因类型，为造山后伸展环境的产物，标志着印支期末秦岭地区俯冲碰撞的板块构造体制已经结束，转入板内构造演化阶段。

THE GENESIS OF THE LAOJUNSHAN RAPAKIVI GRANITE IN THE NORTH QINLING AND THE TECTONIC SIGNIFICANCE

The Laojunshan rapakivi granite occurs in the north Qinling orogenic zone, which is a part of the north Qinlin rapakivi granite zone from Shahewan, Zhuchanggounao to the Qinling ridge. Combining with the regional tectonic environment, researches on the information about geology, lithology and geochemistry have indicated that the Laojunshan rapakivi granite is of the genetic type with mingling of magma, which was the product from an extensional environment after orogeny, indicating the end of the plate structural system formed by subducting and collision in the Qinling area during the end of Indo Sinian epoch, and then turning into the evolution period of inner plate structures.