Abstract New petrographic, lithochemical, in situ U Pb geochronological and Nd isotopes data allowed to propose a petrotectonic model for 1.90–1.88 Ga I-type calc-alkaline granitoids (Terra Preta Massif - TPM, Agua Branca Suite) from the southernmost Uatuma-Anaua Domain (UAD), Ventuari-Tapajos Province (VTP), central Amazonian Craton, Brazil. The main rock facies of the TPM (1898–1885 Ma) vary from quartz monzodiorite to syenogranite, which display dominantly metaluminous to weakly peraluminous composition. A quartz diorite displaying particular petrographic features can be associated with the TPM and it does not seem to have evolved by fractional crystallization. Field and petrographic evidences, supported by trace element modeling, suggest that the quartz diorite has an origin linked to mixing between the TPM granodioritic (60 wt%) and related quartz gabbro (40 wt%) magmas. Lithochemical data show that a great petrographic variation of the TPG's main facies was not caused by fractional crystallization and point to different degrees of melting of the enriched mantle. Main facies also indicate weak positive ƐNd(t) anomalies that suggests upwelling asthenospheric mantle that provided heat to remelt the lower continental crust. The dataset of Nd isotopes and inherited zircon crystals also suggests reworking of Rhyacian granulites (French Guyana Domain-FGD, Maroni-Itacaiunas Province) and Orosirian granulites (Anaua Complex, UAD, VTP) and assimilation of metasedimentary rocks (Cauarane Group, Central Guyana Domain, VTP), collisional granitoids (Serra Dourada Suite, UAD, VTP) and Orosirian orthogneisses (Rio Urubu Complex, CGD, VTP). Sources modeling of lithospheric mantle indicated that it is possible to generate tholeiitic mafic and I-type calc-alkaline melts, by melting of 2.15 Ga komatiitic metabasalts from FGD. A melt fraction of 28 wt% of 2.03 Ga granulites was also able to generate a liquid compatible with the main facies of the TPM. Offset of the slab breakoff in the post-collisional setting caused the asthenospheric mantle input and mixture of depleted melts (highly positive ƐNdt) with enriched melts (negative ƐNdt), resulting in ƐNd(t) values close to zero, which renders the lithospheric mantle as the main isotopic reservoir for the TPM.

中文翻译：

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来自巴西北部的奥罗斯纪 I 型钙碱性花岗岩：亚马逊克拉通中部演化的岩石成因意义

摘要 新的岩石学、岩石化学、原位 U Pb 年代学和 Nd 同位素数据允许提出来自 Uatuma-Anaua 最南端的 1.90-1.88 Ga I 型钙碱性花岗岩（Terra Preta Massif - TPM，Agua Branca Suite）的岩石构造模型Domain (UAD)，文图阿里-塔帕霍斯省 (VTP)，巴西亚马逊克拉通中部。TPM 的主要岩相（1898-1885 Ma）从石英二闪长岩到正长花岗岩不等，显示主要为金属铝质到弱过铝质成分。显示特定岩相特征的石英闪长岩可能与 TPM 相关，它似乎不是通过分步结晶演化而来的。现场和岩相证据，由微量元素建模支持，表明石英闪长岩的起源与 TPM 花岗闪长岩 (60 wt%) 和相关石英辉长岩 (40 wt%) 岩浆之间的混合有关。岩石化学数据表明，TPG 主要相的较大岩相变化不是由分步结晶引起的，而是表明富集地幔的熔融程度不同。主要相还表明 ƐNd(t) 的弱正异常表明上涌的软流圈地幔为下大陆地壳重新熔化提供了热量。Nd 同位素和继承锆石晶体的数据集还表明，Rhyacian 麻粒岩（法属圭亚那域-FGD，Maroni-Itacaiunas 省）和 Orosirian 麻粒岩（Anaua Complex、UAD、VTP）的再加工和变质沉积岩（Cauarane 组，圭亚那中部域）的同化, VTP), 碰撞花岗岩 (Serra Dourada Suite, UAD, VTP) 和 Orosirian orthogneisses (Rio Urubu Complex, CGD, VTP)。岩石圈地幔源模型表明，通过 FGD 中 2.15 Ga 科马提质变玄武岩的熔化，可以产生拉斑基性镁铁质和 I 型钙碱性熔体。28 wt% 的 2.03 Ga 麻粒岩的熔体分数也能够产生与 TPM 的主要相相容的液体。在碰撞后环境中板块断裂的偏移导致软流圈地幔输入和耗尽熔体（高正 ƐNdt）与富熔体（负 ƐNdt）的混合物，导致 ƐNd(t) 值接近于零，这使得岩石圈地幔作为 TPM 的主要同位素储层。岩石圈地幔源模型表明，通过 FGD 中 2.15 Ga 科马提质变玄武岩的熔化，可以产生拉斑基性镁铁质和 I 型钙碱性熔体。28 wt% 的 2.03 Ga 麻粒岩的熔体分数也能够产生与 TPM 的主要相相容的液体。在碰撞后环境中板块断裂的偏移导致软流圈地幔输入和耗尽熔体（高正 ƐNdt）与富熔体（负 ƐNdt）的混合物，导致 ƐNd(t) 值接近于零，这使得岩石圈地幔作为 TPM 的主要同位素储层。岩石圈地幔源模型表明，通过 FGD 中 2.15 Ga 科马提质变玄武岩的熔化，可以产生拉斑基性镁铁质和 I 型钙碱性熔体。28 wt% 的 2.03 Ga 麻粒岩的熔体分数也能够产生与 TPM 的主要相相容的液体。在碰撞后环境中板块断裂的偏移导致软流圈地幔输入和耗尽熔体（高正 ƐNdt）与富熔体（负 ƐNdt）的混合物，导致 ƐNd(t) 值接近于零，这使得岩石圈地幔作为 TPM 的主要同位素储层。