Abstract We present the first regional in-situ zircon U–Pb–Hf isotopic data from metaigneous and metasedimentary rocks from the Paleo- to Mesoproterozoic Rio Apa Terrane (RAT), a crustal fragment outcropping in the central-western Brazil and north-eastern Paraguay. These new ages and Hf isotopic data delineate three magmatic events, which record the construction of the temporally and isotopically distinct Western and Eastern Terranes of the RAT. The Western Terrane comprises the 2100–1940 Ma Porto Murtinho Complex and the 1900–1840 Ma Amoguija Belt, which both define a crustal reworking array in eHfT-time space evolving from a precursor source with Hf TDM age of ca. 2700 Ma. The 1800–1720 Ma Caracol Belt constitutes the Eastern Terrane and yields suprachondritic eHfT signatures up to +7.1, indicating significant juvenile input. The metasedimentary Amolar Group and Rio Naitaca Formation in the Western Terrane have maximum depositional ages of 1850–1800 Ma and subchondritic eHfT signatures down to −5.7, similar to the underlying basement of the Amoguija Belt. In the Eastern Terrane, the Alto Terere Formation has a maximum depositional age of 1750 Ma and mostly suprachondritic eHfT signatures, similar to magmatic rocks of the underlying Caracol Belt. Together, the new igneous and detrital zircon age and Hf isotopic data record a temporal and spatial transition from 2100 to 1840 Ma crustal reworking in the west to more juvenile magmatism at 1800–1720 Ma in the east. This transition is interpreted to reflect convergent margin magmatism associated with periods of subduction zone advance and retreat in an accretionary orogenic setting. Comparison of the eHfT-time signature of the RAT with the Amazonian Craton suggest penecontemporaneous development, with the Western and Eastern Terranes of the RAT being correlative with the Ventuari-Tapajos and Rio Negro-Juruena Province of the Amazonian Craton, respectively. Our new data also reveal that the eHfT signatures of the RAT are distinct from the Maz terrane, which refutes the MARA Block hypothesis.

中文翻译：

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来自 Rio Apa Terrane（巴西）的锆石 U-Pb-Hf 数据揭示的长期活动边缘：对亚马逊克拉通古元古代演化的新见解

摘要 我们展示了来自古至中元古代 Rio Apa Terrane (RAT) 的变火成岩和变沉积岩的第一个区域原位锆石 U-Pb-Hf 同位素数据，RAT 是在巴西中西部和巴拉圭东北部出露的地壳碎片。 . 这些新的年龄和 Hf 同位素数据描绘了三个岩浆事件，它们记录了 RAT 的时间和同位素不同的西部和东部地体的构造。Western Terrane 包括 2100-1940 Ma Porto Murtinho Complex 和 1900-1840 Ma Amoguija 带，它们都定义了 eHfT 时间空间中的地壳改造阵列，该阵列从 Hf TDM 年龄约 2700 马。1800-1720 Ma Caracol 带构成了东地体，并产生高达 +7.1 的球粒上 eHfT 特征，表明显着的幼体输入。Western Terrane 的变质沉积 Amolar 组和 Rio Naitaca 组的最大沉积年龄为 1850-1800 Ma，球粒下 eHfT 特征低至 -5.7，类似于 Amoguija 带的下伏基底。在东地体，Alto Terere 组的最大沉积年龄为 1750 Ma，主要是球粒上的 eHfT 特征，类似于下伏 Caracol 带的岩浆岩。新的火成岩和碎屑锆石年龄和 Hf 同位素数据一起记录了从西部 2100 到 1840 Ma 地壳改造到东部 1800 到 1720 Ma 更年轻的岩浆活动的时空转变。这种转变被解释为反映了在增生造山环境中与俯冲带前进和后退时期相关的会聚边缘岩浆作用。将 RAT 与亚马逊克拉通的 eHfT 时间特征进行比较表明，RAT 的西部和东部地体分别与亚马逊克拉通的 Ventuari-Tapajos 和 Rio Negro-Juruena 省相关。我们的新数据还表明，RAT 的 eHfT 特征与 Maz terrane 不同，这驳斥了 MARA Block 假设。