Abstract The Paranapanema-Sao Francisco convergence is partially recorded in the arc-related high-K calc-alkaline intermediate magmatism of south-eastern Brazil (Southern Brasilia Orogen) during the West-Gondwana assembly. Similar geochemical affinities are widespread in the crustal fault-bounded slice, Sao Roque Domain, as in tectonic domains of the eastern Sao Francisco margin. The Sao Roque Domain comprises metavolcano-sedimentary sequences of Statherian maximum depositional age. Detrital zircon provenance points to a Rhyacian (2.17 Ga) proximal source belonging to the Socorro-Guaxupe Nappe basement. Unprecedented Tonian zircon U-Pb ages suggest a protracted evolution. The domain initiated magmatic activity at 680 Ma (Barro Branco orthogneiss) with weak Hf-Nd radiogenic signatures that agree with the arc evolution of the Socorro-Guaxupe Nappe. Granitoids grading from intermediate metaluminous to evolved peraluminous compositions intruded at 625 Ma (inequigranular orthogneiss) and 620 Ma (Moinho granodiorite). The most voluminous magmatism occurred within 610-590 Ma. Hf-Nd radiogenic compositions of the Ediacaran granitoids imply crustal participation. All granitoids have arc-related affinity with high Sr/Y and LREE, low Nb and Ti, and absence of Eu anomalies that indicate a lower crustal source with residual garnet (±amphibole ±rutile). The petrogenetic and geochronological characterizations favor a retro-arc setting for the Sao Roque Domain. Slab roll-back could have led to the northward migration of magmatism (Socorro-Guaxupe Nappe) producing a chronological gap in the retro-arc. The Ediacaran magmatism was probably triggered by the relaxation of the subducting angle. The last-longing subduction beneath the Paranapanema plate might have contributed to the high-K and radiogenic compositions through relamination. Monazite U-Pb ages from 630 to 600 Ma may be evidence of a thermal episode in the retro-arc, overlapping the syn-collisional metamorphism in the Southern Brasilia Orogen.

中文翻译：

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Serra do Barro Branco orthogneiss：São Roque Domain 西部冈瓦纳河合并的不合时宜的记录

摘要 Paranapanema-Sao Francisco 辐合部分记录在西冈瓦纳大陆组装期间巴西东南部（Southern Brasilia Orogen）的弧相关高钾钙碱性中间岩浆活动中。与圣弗朗西斯科东部边缘的构造域一样，类似的地球化学亲缘关系在地壳断层边界的圣罗克域中广泛存在。Sao Roque 域包括 Statherian 最大沉积时代的变质火山沉积层序。碎屑锆石出处指向属于 Socorro-Guaxupe Nappe 基底的 Rhyacian (2.17 Ga) 近端源。史无前例的托尼亚锆石 U-Pb 年龄表明了长期的演化。该区域在 680 Ma（Barro Branco 正片麻岩）开始岩浆活动，具有较弱的 Hf-Nd 放射成因特征，与 Socorro-Guaxupe Nappe 的弧演化一致。从中间金属铝到演化过铝成分的花岗岩在 625 Ma（不等粒正方麻岩）和 620 Ma（Moinho 花岗闪长岩）侵入。最大量的岩浆活动发生在 610-590 Ma。埃迪卡拉纪花岗岩的 Hf-Nd 放射成因成分意味着地壳参与。所有花岗岩类都具有与高 Sr/Y 和 LREE、低 Nb 和 Ti 的弧相关的亲和力，并且没有 Eu 异常，表明下地壳来源具有残余石榴石（±角闪石±金红石）。岩石成因和地质年代学特征有利于圣罗克域的逆弧环境。板块回滚可能导致岩浆活动（Socorro-Guaxupe Nappe）向北迁移，在逆弧中产生时间间隔。埃迪卡拉纪的岩浆活动可能是由俯冲角的弛豫引发的。Paranapanema 板块下的最后一次俯冲可能通过重新分层促成了高 K 和放射成因的成分。630 至 600 Ma 的独居石 U-Pb 年龄可能是弧后热事件的证据，与巴西利亚造山带南部的同碰撞变质作用重叠。