Geochronology, geochemistry, and tectonic implications of upper Silurian-Lower Devonian meta-sedimentary rocks from the Jiangyu Group in eastern Jilin Province, Northeast China

In this study, we present detrital zircon U--Pb ages and Hf isotopic data and whole-rock geochemical data from meta-sedimentary rocks of the Jiangyu Group in eastern Jilin Province (Northeast China) to constrain the late Silurian -- Early Devonian tectonic evolution of the southeastern Xing'an--Mongolia Orogenic Belt. Two samples of the meta-sedimentary rocks from the Jiangyu Group yielded concordant ages ranging from 2926 to 415 Ma, and the youngest zircon populations of the two samples yielded weighted mean ages of 427 ± 3 and 426 ± 3 Ma, respectively. Combined with reliable published muscovite ⁴⁰Ar-³⁹Ar ages of 408 Ma from the overlying metamorphic ophiolitic melange, these data indicate that the protoliths of the Jiangyu Group were deposited during the late Silurian-Early Devonian Era. A comparison of the U-Pb ages and Hf isotopic data for detrital zircons from northeastern Gondwana and the Jiangyu Group indicates a probable tectonic affinity. The whole-rock geochemical data indicate that the protoliths of the meta-sedimentary rocks from the Jiangyu Group were graywackes deposited in a continental arc setting. Based on the recognition of the early to middle Paleozoic subduction-accretion events along the eastern segment of the northern margin of the North China Craton (NCC), we infer that the subduction-accretion events may have occurred in the Yanbian area followed by one or more arc-continent collisions after the Early Devonian. (author)