SHRIMP zircon U-Pb age, litho- and biostratigraphic analyses of the Huaiyu Domain in South China — Evidence for a Neoproterozoic orogen, not Late Paleozoic-Early Mesozoic collision
Аннотация:In the last few decades, the Late Paleozoic-Early Mesozoic tectonic evolution of South China has been quite controversial.The focus of debate is on both the age of ophiolites and the Late Paleozoic-Early Mesozoic geological and geodynamic environment.The Huaiyu Domain is located in the NE part of South China and exposes numerous significant geological features that are keys to understand the tectonics of South China.In this paper, we present some new evidence on stratigraphy, petrology and SHRIMP zircon U-Pb geochronology, and together with other geological and geochemical data available in the literature, and the following conclusions are suggested: 1) The eastern Jiangnan ophiolites belt, dated at 858±11 Ma by SHRIMP zircon U-Pb method, was generated during the Neoproterozoic, but not the Late Paleozoic; 2) The sedimentary rocks associated with these oceanic rocks do not contain radiolarians but Neoproterozoic acritarchs; 3) During Permian-Early Triassic times, the Huaiyu Domain was dominantly characterized by a shallow sea depositional environment since deep sea sediments are absent; and 4) The pre-Devonian tectonics of South China has been reworked by late polyphase tectonism through the Triassic and the Cretaceous periods.A Late Paleozoic-Early Mesozoic deep marine domain floored by oceanic crust never existed in the study area.The geochronological and structural data do not comply with a Late Paleozoic-Early Mesozoic South China Ocean.
