The Patos Shear System (PSS) is a 20–40 km wide domain of anastomosing shear zones intercalated with non-mylonitic segments at the core of the Borborema Province, a transpressive Neoproterozoic orogen in NE Brazil, part of the reworked São Francisco Craton. We provide new U-Pb, Lu-Hf and Sm-Nd analyses for non-mylonitic basement migmatitic orthogneisses. Four magmatic events (∼3.40, 3.26, 2.68–2.64 and 2.18 Ga), as well as three metamorphic/migmatization ones (∼3.0, 2.1–2.0 Ga and 570–575 Ma) were evidenced. Metamorphism and leucosome injection at ∼570–575 Ma attest the PSS was subjected to high heat from medium- to high-temperature dextral shearing. A distinct Paleoproterozoic (∼2.1–2.0 Ga) migmatization event is probably related to the amalgamation of Neo-Paleoarchean blocks and an older ∼3.0 Ga metamorphic event may represent crustal thickening induced by the collision between small Paleoarchean landmasses. Paleoarchean magmatic protoliths obtained here were emplaced concomitant with TTGs and high-K rocks regionally, and our Hf data from these rocks, after filtering for isotopic disequilibrium during anatexis, combined with a large compilation, point to an apparent mixing of magma derived from a CHUR-like reservoir with older crust, better reconciled, although not conclusively, with a stagnant-lid scenario dominated by plume activity. Hf data from 2.68 to 2.64 Ga old migmatites plot along a conspicuous Meso-Neoproterozoic “reworking array” and our preferred model is that magmatism between 2.9 and 2.6 Ga took place in an accretionary/collisional continental setting, following renewed juvenile additions between ∼3.2 and 2.9 Ga. At last, the crystallization age of ∼2.18 Ga of an orthogneiss is related to another Wilson Cycle. Our data point to reworking of Archean lithologies during the Paleoproterozoic, as evidenced by inherited Archean zircon grains, but Ɛ and Ɛ close to CHUR suggest involvement of more juvenile material as well, consistent with regional data, and the preferred scenario is that of subduction followed by collision.

中文翻译：

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巴西东北部 Borborema 省的古太古代到新元古代地壳形成和混合事件：对大陆地壳生长和改造的影响

帕托斯剪切系统 (PSS) 是一个 20-40 公里宽的网状剪切带区域，其间插有位于 Borborema 省核心的非糜棱岩段，Borborema 省是巴西东北部的新元古代压弯造山带，是改造后的圣弗朗西斯科克拉通的一部分。我们为非糜棱岩基底混合岩正片麻岩提供了新的 U-Pb、Lu-Hf 和 Sm-Nd 分析。证实了四次岩浆事件（∼3.40、3.26、2.68-2.64 和 2.18 Ga）以及 3 次变质/混合岩作用事件（∼3.0、2.1-2.0 Ga 和 570-575 Ma）。 〜570–575 Ma 的变质和隐色体注入证明 PSS 受到中高温右旋剪切的高温作用。一次明显的古元古代（~2.1-2.0 Ga）混合岩化事件可能与新古太古代地块的合并有关，而一次较老的~3.0 Ga变质事件可能代表了古太古代小陆块之间碰撞引起的地壳增厚。这里获得的古太古代岩浆原岩与 TTG 和高 K 岩石一起就位，我们从这些岩石中获得的 Hf 数据在深熔过程中过滤同位素不平衡后，结合大量的汇编，表明来自 CHUR 的岩浆明显混合。类似地壳的储层，虽然不是决定性的，但更好地协调了由羽流活动主导的停滞盖情景。 2.68 至 2.64 Ga 古老混合岩的 Hf 数据沿着明显的中新元古代“改造阵列”绘制，我们的首选模型是 2.9 至 2.6 Ga 之间的岩浆活动发生在增生/碰撞大陆环境中，继~3.2 至 3.2 至2.9 Ga。最后，正片麻岩~2.18 Ga的结晶年龄与另一个威尔逊旋回有关。我们的数据表明太古代岩性在古元古代发生了改造，继承的太古代锆石颗粒证明了这一点，但接近 CHUR 的 Ɛ 和 Ɛ 表明还涉及更多新生物质，与区域数据一致，并且首选方案是随后的俯冲通过碰撞。