大别山南部黄镇-凉亭河一线宿松变质杂岩岩石学和峰期变质温压条件及与高压榴辉岩对比研究

通过对宿松变质杂岩的野外地质观测、岩相学和热力学评价及其峰期变质温压条件的空间变化特征的研究,并对比南大别高压单元研究结果,探讨宿松变质杂岩的岩石构成和变质特征。研究表明宿松变质杂岩自北向南可分为I、II和III三个带,主体仅经历了绿帘角闪岩相至角闪岩相的变质作用,温压范围为t=398～613℃和p=0.61～1.53GPa,平均温压值为t=517℃±50℃和p=1.03±0.21GPa。该变质杂岩未显示任何蓝片岩相的变质特征,其内部也没有温度分带或连续变化的趋势。对比南大别高压单元的峰期变质条件,它们压力差至少可达p=0.92GPa,温度差可能在t=45℃,两者应在构造作用下叠置在一起。

Petrology and Peak p-t Conditions of Susong Metamorphic Complex in the Huangzhen-Liangtinghe Area in the Southern Dabie Mountain and Comparison with high-Pressure Eclogites

Based on the field geological survey, lithography and thermodynamics evaluation, and p-t condition change of peak metamorphism in the Susong metamorphic complex (SSC), this study discussed the lithological compositions and metamorphic features of the Susong metamorphic complex (SSC). The results indicate that the Susong complex can be divided into three zones from north to south, with epidote-amphibolite to amphibolite facies as the main metamorphism. The temperature and pressure ranged from 398 to 613℃ and 0.61～1.53GPa, respectively, with average p-t conditions of 517℃±50℃ and 1.03±0.21GPa. But the metamorphic complex does not show any characteristics of glaucophane facies and temperature zonation or gradual temperature trend within the complex. Compared with the peak p-t conditions of the HP-unit from the South Dabie Terrane, differences of time and temperature between the SSC and HP-unit from the South Dabie Terrane is at least 0.92 GPa and 45℃ gap, indicating the SSC and HP-unit from the South Dabie Terrane should be juxtaposed under tectonic activity.