Abstract Paleoproterozoic retrogressed eclogite (retroeclogite) occurs in the Itaguara Sequence included in the suture zone formed by collision between the Archean Divinopolis and Campo Belo/Bonfim Complexes in the southern Sao Francisco Craton, which represents the South American counterpart of the African Congo Craton. The Itaguara retroeclogite contains scarce omphacite and phengite but abundant garnet porphyroblasts embedded in a fine-grained, amphibole, biotite and quartz-bearing matrix. The 2.20 ± 0.05 Ga eclogitization event (garnet and whole rock Sm-Nd isochronic age) of the E-MORB protolith (TDM ~ 2.47 Ga) is recorded by omphacite formation during high-pressure prograde stage in amphibole eclogite facies due to ~70 km depth subduction process. Amphibole eclogite facies metamorphic peak stage of 17–20 kbar and 600–700 °C occurred during ~2.1 Ga continental collision. Tectonic exhumation-related decompression during collision probably triggered partial melting of the eclogitic rock. Finally, decompression late stage estimated between 5 and 8 kbar and 550–650 °C under amphibolite facies overprint during orogenic collapse was responsible for appearance of kelyphitic reaction rims (symplectite) around garnet crystals. As its Paleoproterozoic contemporary analogues from Congo Craton, the Itaguara retroeclogite is one of the oldest records of the modern-style plate tectonics.

中文翻译：

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来自圣弗朗西斯科/刚果克拉通的古元古代 Itaguara 后榴辉岩的岩石学、地球化学和 Sm-Nd 系统学：现代板块构造最古老的记录之一

摘要 古元古代后退榴辉岩（retroeclogite）产于圣弗朗西斯科克拉通南部的太古宙Divinopolis与Campo Belo/Bonfim杂岩碰撞形成的缝合带内的Itaguara层序，代表了非洲刚果克拉通的南美对应物。Itaguara 后榴辉岩含有稀有的绿辉石和菱镁矿，但含有大量嵌在细粒角闪石、黑云母和含石英基质中的石榴石斑状晶。E-MORB原岩（TDM~2.47 Ga）的2.20±0.05 Ga榴辉石化事件（石榴石和全岩Sm-Nd等时年龄）记录于角闪岩榴辉岩相高压前积阶段由于~70 km导致的绿辉石形成深度俯冲过程。角闪石榴辉岩相变质峰值阶段为 17-20 kbar 和 600-700 °C 在~2 期间发生。1 Ga 大陆碰撞。碰撞期间与构造剥脱相关的减压可能引发了榴辉岩的部分熔化。最后，在造山带崩塌期间角闪岩相叠印下估计在 5 到 8 kbar 和 550-650 °C 之间的减压后期是造成石榴石晶体周围出现钾长石反应边缘（辛辉石）的原因。作为来自刚果​​克拉通的古元古代当代类似物，Itaguara 后榴辉岩是现代板块构造最古老的记录之一。造山崩塌期间角闪岩相叠印下估计在 5 到 8 kbar 和 550–650 °C 之间的减压后期是造成石榴石晶体周围出现钾长石反应边缘（辛辉石）的原因。作为来自刚果​​克拉通的古元古代当代类似物，Itaguara 后榴辉岩是现代板块构造最古老的记录之一。造山崩塌期间角闪岩相叠印下估计在 5 到 8 kbar 和 550–650 °C 之间的减压后期是造成石榴石晶体周围出现钾长石反应边缘（辛辉石）的原因。作为来自刚果​​克拉通的古元古代当代类似物，Itaguara 后榴辉岩是现代板块构造最古老的记录之一。