四川后龙门山中压变质地体的形成时代问题

THE AGE OF FORMATON OF THE HOULONGMENSHAN INTERMEDIATE-PRESSURE METAMORPHIC TERRANE IN SICHUAN

摘要: 该变质地体发育在古生界—三叠系的地槽型建造之中,属中压相系的区域动力热流变质。它生成于印支晚期,并伴随着强烈的褶皱变形、混合岩化和花岗岩化作用。它起源于巴颜喀拉地块与扬子地块之间碰撞,热流上升可能和陆内的俯冲及壳内局部熔融带的产生有关。该中压变质带与西侧三叠系复理石的低压过渡型区域动力热流变带及区域动力变质带相伴生。

Abstract: The metamorphic terrane in qustion occurs in a Paleozoic to Triassic geosynclinal formation.The metamorphism belongs to regional dynamothermal metamorphism of intermediate-pressure facies series.It was formed in the late Indosinian period,accompanied by strong folding,migmatization and granitization. It originated from collision of the Bayan Har block and the Yangtze block. The ascent of the thermal flow might be related to intracontinental subduction and intracrustal partial melting.This intermediate-pressure metamorphic belt is associated with low-pressure transitional regional dynamothermal metamorphic belt and regional dynamic metamorphic belt in Triassic flysch to its west.