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-寒武纪时期的板块拼合过程，涉及现今分布于南美东部与非洲西部的多块古老地壳地体的碰撞。针对南美里贝拉（Ribeira）造山带、多姆费利西亚诺（Dom Feliciano）造山带以及非洲加里普（Gariep）造山带、达马拉（Damara）造山带的典型变沉积岩单元，研究获取了铀-铅（SHRIMP）碎屑锆石年代数据，以此对推测缝合带两侧的潜在沉积物源区进行约束。里贝拉造山带的碎屑锆石年代均为古元古代和太古代；多姆费利西亚诺造山带则含有中元古代至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。研究提出，里贝拉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；而达马拉造山带与加里普-罗查（Gariep–Rocha）造山带的沉积物源区则来自纳马夸（Namaqua）造山带。多姆费利西亚诺造山带的沉积物主要来自南美一侧，仅少量源自非洲源区。上述研究结果揭示了推测的西冈瓦纳缝合带两侧碎屑锆石特征的显著差异：西侧锆石来源于特征鲜明的南美基底源区，东侧则来源于特征鲜明的非洲源区。