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

摘要

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 ~(40)Ar-~(39)Ar ages of 408 Ma from the overlying metamorphic ophiolitic mélange,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.