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在大别山的北大别地体,有许多辉石岩-辉长岩侵入体出露(图1),已有的年龄数据中仅有一个祝家铺辉石岩Sm-Nd等时年龄((230±30.7)Ma),显示它为同碰撞岩浆岩.然而,它们的角闪石~(40)Ar/~(39)Ar年龄为(124.1±0.6),(125±0.5)和(129.7±0.6)Ma.一些作者根据该类岩石没有变形变质的特征、与围岩(片麻岩)的侵入关系以及~(40)Ar/~(39)Ar年龄认为该区辉石岩-辉长岩是碰撞后侵入岩,还将大别山缺少同碰撞岩浆岩作为俯冲陆壳不可能析出大量流体交代楔形地幔并引发部分熔融的旁证.因此弄清这类侵入岩的真实侵位时代具有重要的地质、地球化学意义.我们研究了北大别任家湾含长斜方辉石岩的Sm-Nd年代学,证明它们是同碰撞侵入岩.
There are many pyroxene-gabbro intrusion in the Dabie Mountains of the North Dabie (Fig. 1). Only one of the existing age data of the Zhijiapo pyroxene Sm-Nd isochron age ((230 ± 30.7 Ma), indicating that it is a collisional magmatic rock. However, their amphibole ~ (40) Ar / ~ (39) Ar ages are (124.1 ± 0.6), (125 ± 0.5) and (129.7 ± 0.6 Based on the fact that this type of rock is characterized by no metamorphism and metamorphism and intrusiveness to the surrounding rock (gneisses) and ~ (40) Ar / ~ (39) Ar ages, some authors believe that the pyroxene-gabbro After the collision, it invaded the rock and also lacked the collisional magmatic rocks in the Dabie Mountains as the subducted continental crust. Therefore, it is impossible to deposit a large amount of fluid to account for the wedge-shaped mantle and lead to partial melting. Therefore, it is important to clarify the true geological emplacement times of these intrusive rocks. Chemical Significance We studied the Sm-Nd chronology of the orthodox rhodochrosite from the North Dabie Renjiawan, and proved them to be a collisional intrusive rock.