The late Neoproterozoic-early Paleozoic marked an important interval in Earth history, during which there was the transition from the breakup of Rodinia to the assembly of the Gondwana supercontinent. The South China Block (SCB) is a key part of Gondwana, and is an important component in its paleogeographic reconstructions. Sedimentary provenance analysis has been applied to constrain the SCB source-to-sink systems and hence to reconstruct its position within Gondwana. However, previous studies have mainly undertaken detrital zircon provenance analysis on Cryogenian-Ordovician strata from a single sedimentary basin, leading to different paleogeographic models for the SCB within the Gondwana supercontinent. To resolve these challenges, detrital rutile, apatite and zircon data of Cryogenian to Ordovician successions from four sub-basins in the Cathaysia Block of South China were compiled in addition to acquiring new data from four samples. Detrital rutile and apatite from the Cryogenian to Ordovician successions share similar 650–500 Ma major age populations, which are considered mainly derived from Pan-African orogens in western Australia, India and East Antarctica. Most detrital rutiles are derived from amphibolite- or eclogite-facies metamorphic rocks, with appreciable proportions (22–42%) derived from metamafic rocks. The apatite data demonstrate a significant amount of metamorphic- (52–72% of all grains) and mafic-derived (40–70% of igneous-derived grains) populations. Three provenance switches are demonstrated by the detrital apatite data and indicate the exhumation of Pan-African orogens in the late Cryogenian, Ediacaran-Cambrian, and early Ordovician in the source areas. In contrast, the detrital zircon data are characterized mainly by 1300–900 Ma igneous populations from late Mesoproterozoic-early Neoproterozoic orogens in western Australia and India. Provenance switches caused by exhumation of the orogenic sources and the Cathaysia Block in the late Ediacaran and middle Cambrian are detected. The trace element systematics of rutile and apatite along with zircon Lu-Hf isotopic compositions reflect similar temporal trends in the proportions of materials derived from (meta)mafic rocks and juvenile crust. They support increased input of juvenile crust including (meta)mafic source rocks in the Ediacaran and subsequent exhumation. Collectively, the variations in age and lithology of source(s) are best detected by the detrital apatite dataset, especially for metamorphic- and mafic-derived sources when information from detrital rutile can also be integrated. Our analysis provides a more refined and complete understanding of the provenance evolution of the Cathaysia basins by this analysis of detrital multi-mineral datasets, and places further constraints on reconstructions of the South China Block within Gondwana.

中文翻译：

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碎屑多矿源约束对冈瓦纳大陆华南地块重建的影响


新元古代晚期-古生代早期标志着地球历史上的一个重要时期，在此期间经历了从罗迪尼亚的分裂到冈瓦纳超大陆的聚合的过渡。华南地块（SCB）是冈瓦纳大陆的重要组成部分，是古地理重建的重要组成部分。沉积物来源分析已应用于限制SCB源-汇系统，从而重建其在冈瓦纳大陆内的位置。然而，以往的研究主要对单个沉积盆地的成冰系-奥陶系地层进行碎屑锆石物源分析，导致冈瓦纳超大陆内部SCB的古地理模型不同。为了解决这些挑战，除了从四个样品中获取新数据外，还编制了华南华夏地块四个次盆地的冰冻纪至奥陶纪序列的碎屑金红石、磷灰石和锆石数据。成冰纪至奥陶纪的碎屑金红石和磷灰石具有相似的 650–500 Ma 主要年龄群体，被认为主要来自澳大利亚西部、印度和东南极洲的泛非造山带。大多数碎屑金红石源自角闪岩相或榴辉岩相变质岩，其中相当一部分（22-42%）源自变质岩。磷灰石数据表明存在大量变质颗粒（占所有颗粒的 52-72%）和镁铁质颗粒（占火成颗粒的 40-70%）。碎屑磷灰石数据证明了三个物源转换，并表明源区晚成冰纪、埃迪卡拉纪-寒武纪和早奥陶世泛非造山带的折返。 相比之下，碎屑锆石数据的特征主要是来自澳大利亚西部和印度的中元古代晚期-新元古代早期造山带的 1300–900 Ma 火成岩种群。检测到埃迪卡拉晚期和中寒武世造山源和华夏地块折返引起的物源转换。金红石和磷灰石的微量元素系统学以及锆石 Lu-Hf 同位素组成反映了来自（变）镁铁岩和新生地壳的材料比例的相似时间趋势。它们支持新生地壳的增加，包括埃迪卡拉系的（变）镁铁质烃源岩和随后的折返。总的来说，碎屑磷灰石数据集可以最好地检测源的年龄和岩性变化，特别是对于变质和镁铁质来源的源，当来自碎屑金红石的信息也可以被整合时。通过对碎屑多矿物数据集的分析，我们的分析提供了对华夏盆地物源演化的更精细和完整的理解，并进一步限制了冈瓦纳大陆内华南地块的重建。