Abstract:

Abstract:  Based on our newly firsthand data obtained recently from regional geological survey and previous research results, we have analyzed in detail the geological features, distribution, forming ages and NdSr isotopic characteristics of Caledonian granitoids in the eastern segment of South China.The tectonic setting forming Caledonian granitoids were discussed, which includes the ages of ultramaficmafic rocks and volcanic rocks that outcrop in the study areas, the deposited environment of sedimentary rocks during the SinianOrdovician period, and deformation patterns of the Caledonian structures.Results suggest that the Caledonian granitoids were mainly formed between 410460 Ma corresponding to the period from the Middle Ordovician to the Early Devonian. Geochemically, most of granitoids belong to the Stype that their magma were derived from the partial fusion of continental crust,but a few granitoids show characteristics of type I granitoids that the magma contains mantle materials. There is neither a largescale Caledonian type I granitoids that were related to plate subduction, nor the synchronous island arctype volcanic rocks in the study area; the sedimentary environment during the SinianOrdovician period is mainly a shallow sea and partly a bathyal one. We propose that the tectonic setting forming Caledonian granitoids  mainly belongs to intraplate tectonic environment.

Key words:

Key words: granitoids; geological features; tectonic setting; Caledonian period; eastern segment of South China