基于花岗岩类形成的岩浆动力学过程的分析判别其形成的构造背景——以大别碰撞带大王寨岩体为例

TECTONIC DISCRIMINATION OF GRANITOIDS BASED ON ANALYSES OF MAGMA -DYNAMIC PROCESSES: An Example from Neoproterozoic Dawangzhai Intrusion, Dabie Collision Belt

花岗岩类的成分既受构造背景控制,又与岩浆来源、起源和演化过程有关。因此,在使用构造—化学判别图确定形成环境时,应当研究控制岩石成分变异和岩石类型的岩浆动力学过程和区域地壳组成特点,并对投图的元素和岩石加以选择。由于不同环境中形成的岩石,在构造样式、侵位机制、岩石组合和与区域变形变质作用的时空关系方面都有差别,因此,这些非化学特征也能提供有关构造演化的证据。根据上述思路,对大别山南麓的大王寨岩体进行了研究。结果表明,该岩体是在新元古代扬子地块与大别山地块碰撞过程中形成的。

Granitoid composition is controlled by tectonic settings, magma sources, initiation and evolution processes. Thus we should study the magma-dynamic processes and compositional features of the regional crust controlling the rock composition variation and granitoid types, and select the suitable elements and rocks in order to discriminate tectonic settings using the tectonic chemical plots. As granitoid intrusions formed on the different tectonic settings are different in structural patterns, emplacement mechanism, rock asssociations, and temporal and spatial relations between them and regional deformation and metamorphism, all these nonchemical characteristics may provide evidences of tectonic evolution. On the basis of these thinking, we study the Dawangzhai intrusion in South Dabie Mountain. Synthetical analyses show that the Dawangzhai intrusion was formed by the collision between the Yangtze plate and the Dabie microplate.