相山铀矿田变质基底片岩的变质作用研讨

The prob on the Metamorphic Process of Schist in the Metamorphic Basement of Xiangshan Uranium Mineral Field

在相山铀矿田的早中元古代变质基底中,出露一套云母片岩。按照片岩中的变质特征矿物,可划分为黑云母带、石榴石带和十字石带,与著名的巴罗带中的三个变质带相对比具有相同的矿物组合。该套片岩主要由富铝矿物十字石、铁铝榴石和大量黑云母组成,因而其原岩以粘土岩为主。由于片岩中含有大量黑云母和石榴石,这为利用石榴石、黑云母探讨变质作用的温度压力条件提供了方便,利用矿物温度压力计得到的温度为500～600℃,压力约0.5Gpa。在晚元古代以前该地区至少发生过两次热动力变质作用。

There is a suit of mica schist among metamorphic basement of Early-Middle Proterozoic era at Xiangshan Uraniun Mineral Field. According to distinctive minerals for metamorphic process, it can be divided into three zones: biotite zone, garnet zone, staurolite zone. They have the same mineral assemblage as the famous (Barrow’s) three zones. That suit of schist contans a large number of abundant aluminium mineral: staurolite, almandine and biotite, so the primitive is mostly clayrock. Since the schist contains a large number of biotite and garnet, we can obtain the condition of metamorphic temperature and pressure by using the garnet-biotite conveniently. The range of temperature obtained by using the mineral thermometer-pressure-meter is from 500 ℃ to 600 ℃, and the measured pressure is approximately 0.5 Gpa. Before Later Proterozoic era, in this area more than two times of thermodynamic metamorphism took place.