West Gondwana amalgamation based on detrital zircon ages from Neoproterozoic Ribeira and Dom Feliciano belts of South America and comparison with coeval sequences from SW Africa

Neoproterozoic–Cambrian amalgamation of West Gondwana involved the collision of several terranes of older crust that are now in eastern South America and western Africa. U–Pb (SHRIMP) detrital zircon ages from representative metasedimentary units of the Ribeira and Dom Feliciano belts (South America) and Gariep and Damara belts (Africa) provide constraints on the possible sediment source areas across probable suture zones. Ribeira detrital zircons are Palaeoproterozoic and Archaean. For the Dom Feliciano Belt, a contribution of Meso- and Neoproterozoic zircons is present, which definitely indicate Neoproterozoic sedimentation. It is proposed that the inflow of material to the Ribeira basin was essentially derived from the Paranapanema and Rio de la Plata cratons, whereas for the Damara and Gariep–Rocha belts source areas were from the Namaqua Belt. The Dom Feliciano Belt received sediments from the South American side and to a lesser degree from African sources. These results highlight the differences in the detrital zircon signatures across a proposed West Gondwanan suture, with those in the west being derived from distinctive South American basement sources and those in the east from distinctive African sources.

西冈瓦纳（West Gondwana）在新元古代-寒武纪时期的大陆拼合过程，涉及现今分布于南美东部与西非的多个古老地壳地体的碰撞事件。针对南美里贝利亚（Ribeira）带、多姆费利西亚诺（Dom Feliciano）带以及非洲加里普（Gariep）带、达马拉（Damara）带的典型变沉积岩单元，本次研究开展了铀-铅（U-Pb）高灵敏度离子探针质谱（SHRIMP）碎屑锆石定年，所得数据为推测缝合带两侧的潜在沉积物源区提供了限定条件。里贝利亚带的碎屑锆石形成时代以古元古代和太古代为主。而多姆费利西亚诺带则包含中元古代-新元古代的锆石组分，这明确指示其沉积作用发生于新元古代。研究表明，里贝利亚盆地的沉积物物质主要源自帕拉佩内马（Paranapanema）克拉通与拉普拉塔河（Rio de la Plata）克拉通；达马拉带与加里普-罗恰（Gariep–Rocha）带的沉积物源区则均来自纳马夸（Namaqua）带。多姆费利西亚诺带的沉积物同时来自南美一侧，且仅在较小程度上接收非洲物源的输入。上述研究结果凸显了推测的西冈瓦纳缝合带两侧碎屑锆石特征的显著差异：缝合带西侧的锆石物源源自特征鲜明的南美基底，东侧则来自特征鲜明的非洲基底。