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对侵位于西秦岭造山带西段中下三叠统隆务河群中的然果儿岗花岗闪长岩进行年代学研究,探讨其形成环境。结果表明,花岗闪长岩中锆石Th/U比值较高,锆石内部发育振荡环带,具岩浆成因特点;花岗闪长岩的结晶年龄为(227±4)Ma(MSWD=2.0),表明其形成时代为晚三叠世卡尼期。然果儿岗花岗闪长岩形成于后碰撞环境,或者至少是由同碰撞到后碰撞的转折阶段。
The Gaguo Er granodiorite intrusive in the middle and lower Triassic Longwuhe Group in the western part of the western Qinling orogenic belt is studied for its chronology and its formation environment is discussed. The results show that the ratio of Th / U zircon in granodiorite is high, and the oscillation zone of zircons is characterized by magmatic origin. The crystallization age of granodiorite is (227 ± 4) Ma (MSWD = 2.0 ), Indicating that the formation of the Late Triassic Carniti period. However, the granite is formed in the post-collision environment, or at least the transitional phase from collisions to post-collisions.