横涧花岗斑岩成因探讨

PROBE ON PETROGENSIS OF HENG JAIN'S GRANOPHYRE

横涧花岗斑岩是相山铀矿田的主要含矿岩石之一。在横涧花岗斑岩中有许多残留体。通过对残留体的研究,发现震旦系变质岩和残留体及花岗斑岩间,在化学成分上有线性变化关系和结构特征上的联系,认为横涧花岗斑岩是S型花岗岩,是由原岩震旦系变质岩通过重熔作用而形成的。由于只存在堇青石而缺失石榴子石,重熔作用开始于KMASH体系,随着温度升高而转入复杂的KFMASH体系,重熔岩浆的温度为770～850℃,压力为2.5×10~2～4.5×10~2 Pa。

Heng Jian's granophyre,in which many restites may be seen,is one of main ore-rocks in Xiang Shan uranium deposits.After investigating on them.the Linear relation between the Heng Jian's granophyre and Sinian's metamorphic rocks and restites in the chemical composition and fabric is discovered.It is considered that Heng Jian'sgranophyre belongs to S-type granite which is formed by anatexitation from Sinian period metamorphic rocks.According to the presence of cordierite and ab- sence of garnet in restites,it is implied that melting took place in the simple KFMASH and then ex- tended into the more complex KMASH system.The temperature of anatectic magma is about 770~ 850℃,and pressure is 2.5×10~8~4.5×10~3 Pa.