Abstract The Chafalote Metamorphic Suite, located in the Uruguayan sector of the Punta del Este Terrane, southeasternmost Dom Feliciano Belt, comprises semipelitic, migmatitic metapelites, mafic granulites, and calc-silicate/amphibolitic gneisses. These supracrustal rocks occur as roof pendants in a granodiorite belonging to the Cerro Olivo Complex. The main structure of the Chafalote Metamorphic Suite is a composite S0/S1 banding, related to the main deformation event (D1) developed under upper-amphibolite/granulite facies conditions. This work presents an integrated study on the latter rocks, involving different geochronological methods (monazite U-Pb LA-ICP-MS and zircon U-Pb SHRIMP) and whole rock Sm-Nd isotope data in order to better understand the metamorphic evolution of the Chafalote Metamorphic Suite during the amalgamation of the SW Gondwana paleocontinent in the Neoproterozoic. The studied rocks record a peak metamorphic event (M2) occurred at around 660 Ma (monazite U-Pb ages), which was followed by decompression and partial melting (M3 event) at around 640 Ma (zircon U-Pb ages), probably during the late stages of the D1 event. The retrograde methamorphic event (M4) is related to the transition between the D1 and the development of NE-SW striking, low-grade sinistral shear zones (D2 event) and intrusion of syn-to post-orogenic Brasiliano granitoids of the Aigua Batholith at around 600 Ma. The metamorphic conditions, together with geochronological and isotopic similarities, allow the correlation between the studied high-grade metasedimentary rocks and those from the Paso del Dragon Complex in Uruguay, and from the Varzea do Capivarita, Arroio Grande, and Telho Complex in Brazil. The latter rocks possibly share similar source areas and represent different portions of the Neoproterozoic fore-arc and/or back-arc basins developed in the Dom Feliciano Belt during the Brasiliano/Pan-African orogenic cycle.

中文翻译：

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Chafalote Metamorphic Suite（乌拉圭）：对埃斯特角城演化的思考

摘要 Chafalote Metamorphic Suite 位于Dom Feliciano 带东南部的Punta del Este Terrane 的乌拉圭段，包括半泥质、混合质变泥质岩、镁铁质麻粒岩和钙硅酸盐/角闪质片麻岩。这些上地壳岩石在属于 Cerro Olivo 复合体的花岗闪长岩中作为屋顶垂饰出现。Chafalote 变质岩组的主要结构是复合 S0/S1 带，与在上角闪岩/麻粒岩相条件下发育的主要变形事件 (D1) 相关。这项工作对后者的岩石进行了综合研究，涉及不同的年代学方法（独居石 U-Pb LA-ICP-MS 和锆石 U-Pb SHRIMP）和全岩 Sm-Nd 同位素数据，以更好地了解西南冈瓦纳古大陆合并过程中 Chafalote 变质岩套的变质演化在新元古代。研究的岩石记录了在 660 Ma（独居石 U-Pb 年龄）附近发生的峰值变质事件（M2），随后在 640 Ma（锆石 U-Pb 年龄）附近减压和部分熔化（M3 事件），可能在D1事件的后期阶段。逆行变质事件 (M4) 与 D1 之间的过渡和 NE-SW 撞击的低品位左旋剪切带 (D2 事件) 的发展以及 Aigua 基岩的同向到造山后巴西花岗岩类的侵入有关。大约 600 马。变质条件，连同地质年代学和同位素相似性，允许研究高品位变质沉积岩与来自乌拉圭的 Paso del Dragon 杂岩体以及来自巴西的 Varzea do Capivarita、Arroio Grande 和 Telho Complex 的变质沉积岩之间的相关性。后者的岩石可能具有相似的源区，代表了巴西利亚诺/泛非造山旋回期间在 Dom Feliciano 带中发育的新元古代前弧和/或弧后盆地的不同部分。