河南桐柏麻粒岩相变质作用的p-t条件

The p-t conditions of granulite_facies metamorphism in Tongbai area, Henan Province

地处华北板块南缘的桐柏麻粒岩区 ,主要以长英质麻粒岩为主。通过矿物化学及矿物组合特征的研究 ,结合温压计计算得出桐柏麻粒岩变质条件为 70 0～ 84 0℃、0 .6 1～ 0 .85GPa ,属于典型中压麻粒岩 ,地温梯度大致为 2 8～ 31℃ /km。桐柏麻粒岩相变质作用可能发生于早古生代晚期。

There are mainly felsic granulites in Tongbai area located at southern fringe of the North China plates. A study of the mineral chemistry and the features of the mineral paragenesis and the calculation with thermobarometers revealed that the granulites in Tongbai area were formed under the p-t conditions of 700～840℃ and 0.61～0.85 GPa, belonging to typical medium_pressure type, and the geothermal gradient is approximately from 28 to 31℃/km. The granulite facies metamorphism probably occurred at the late stage of Early Palaeozoic.