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在华夏地块浙江龙游地区发现了榴辉岩退变形成的石榴石角闪岩,其变质演化可分为3个阶段,分别为峰期榴辉岩相阶段(M1),矿物组合为绿辉石+石榴子石变斑晶(核部)+石英;峰后后成合晶阶段(M2),矿物组合为石榴子石变斑晶(边部)+单斜辉石变斑晶+斜长石,峰期榴辉岩相绿辉石在该阶段形成榴辉岩典型的降压分解结构;退变质角闪岩相阶段(M3),矿物组合为角闪石+斜长石,并在石榴子石边部形成角闪石和斜长石的反应边、后成合晶以及斜长石冠状体.由于强烈的退变质过程的影响,传统矿物温压计方法只能得到退变质角闪岩相的温压条件,获得T=664~691℃,P=0.68~0.73 GPa.石榴子石成分环带表明该退变榴辉岩在峰后经历了一近等温降压过程.因此,结合岩相学分析、石榴子石成分剖面和退变质角闪岩相温压数据,可作出退变质过程的顺时针P-T轨迹,与碰撞造山过程一致.故该退变榴辉岩是华夏地块加里东期碰撞造山过程的产物,是华夏地块加里东期碰撞造山事件的新证据.
The garnet amphibolite from degenerated eclogites was found in the Longyou area, Zhejiang Province, China. Its metamorphic evolution can be divided into three phases, namely the peak eclogite facies (M1), the mineral assemblage of green Pyroxene + garnet porphyritic (nuclei) + quartz; the posterior-positonic crystallization stage (M2), the mineral assemblage of garnet porphyrite The pyrochlores of the eclogitic facies at the peak and peak stage formed the typical step-down decomposition structure of eclogites at this stage. The retrogressive amphibolite facies (M3) and the mineral assemblage were amphibole + plagioclase, The reaction edge of amphibole and plagioclase, the posterior conglomerate and plagioclase corolla are formed on the edge of the quarzite. Due to the strong degenerate process, the traditional mineral thermometer method can only get the degenerated amphibolite facies The temperature and pressure conditions obtained T = 664 ~ 691 ℃, P = 0.68 ~ 0.73 GPa. The zoning of garnet components indicates that the degenerate eclogite undergoes a nearly isothermal buck process after the peak. Therefore, combining lithofacies Analysis of the pomegranate composition profile and the retrograde amphibolite facies temperature and pressure data can be made degenerate process of clockwise PT trajectory, consistent with the collision orogenic process, so the degeneration China is a land pyroxenite Caledonian orogenic process of the product is new evidence of Chinese land Caledonian orogenic event.