辽西建平杂岩高压麻粒岩相变质作用的P-T条件及其地质意义  

Metamorphic P-T conditions and geological significance of high-pressure granulite from the Jianping complex, western Liaoning province.

作　　者：魏春景[1] 张翠光[1] 张阿利[1] 伍天洪[1] 李江海[1] 

机构地区：[1]北京大学地质学系,北京100871

出　　处：《岩石学报》2001年第2期269-282,共14页Acta Petrologica Sinica

基　　金：国家自然科学基金 (编号 :49832 0 30和 49772 10 4)

摘　　要：辽西建平杂岩中广泛发育高压麻粒岩块体 ,其特征为在基性岩中出现石榴石 +单斜辉石 +斜长石 +石英±角闪石 ,利用 TWQ方法结合传统地质温压计估算其变质条件为 T=785～ 82 0℃ ,P=1.0 5～ 1.17GPa。高压麻粒岩区的其他岩石如石榴石二辉麻粒岩等虽然不出现典型的高压麻粒岩矿物组合 ,但其变质条件相同。研究表明它们之间矿物组合的不同系由其全岩成分 ,尤其是 Si O2 含量不同所致。因此辽西高压麻粒岩相变质作用是区域性的。该区高压麻粒岩的特征与泛非造山带和西澳的高压麻粒岩相似 ,也符合高压麻粒岩的经典定义 ,但与在华北克拉通其他地区报道的“高压麻粒岩”High pressure granulites are extensively developed in the Jianping complex, western Liaoning province. They are characterized by garnet + clinopyroxene + plagioclase + quartz F hornblende in basic rocks, the metamorphic P-T conditions of which have been estimated as T = 785 similar to 820 C , P = 1.05 similar to1.17GPa by TWQ program combining with relative conventional geothermobarometers. The other kind of rock in the complex has no typical mineral assemblages as the basic rocks I but both of them show identical metamorphic P-T conditions. The difference in mineral assemblage is related with their protolith compositions, especially with the Variance in SiO2 contents. Consequently, the high-pressure granulitic metamorphism from the western Liaoning province is extensive in the region which, characteristically, can be correlated with those from Pan-Africa and western Australia and is also in accordance with the conventional definition of high-pressure granulite facies. However, it has some differences with the 'high-pressure granulites' reported from the other regions of the North China Platform.

关 键 词：高压麻粒岩 变质作用 建平杂岩 温度 压力条件 矿物组成 

分 类 号：P588.346[天文地球—岩石学]