Zircon U–Pb–Hf isotopic and whole-rock geochemical studies of Paleoproterozoic metasedimentary rocks in the northern segment of the Jiao–Liao–Ji Belt, China: Implications for provenance and regional tectonic evolution

Abstract

This study examines the original nature, tectonic setting, and evolution of Paleoproterozoic metasedimentary rocks of the North Liaohe and Laoling groups of the northern segment of the Jiao–Liao–Ji Belt, in the northeastern margin of the Eastern Block of the North China Craton, using new petrological, whole-rock geochemical, geochronological, and Lu–Hf isotope data. Zircons in the metasediments are magmatic and metamorphic in origin, yielding peak ages of 2.03Ga for the deposition of the protoliths of the metasedimentary rocks, and 1.90 and 1.85Ga for their metamorphism. Geochemical analyses indicate the protoliths contained sandy, wacke, and claystone material, with minor shale, derived from Paleoproterozoic granites, coeval acidic meta-volcanic rocks, Meso- and Neo-Archean basement granites, and Paleoproterozoic meta-mafic rocks. Using regional geological and new Lu–Hf isotopic data, we propose that the protoliths of the metasedimentary rocks of the North Liaohe and Laoling groups in the northern segment of the Jiao–Liao–Ji Belt were deposited in a back-arc basin setting. This region experienced two crustal growth events, at 2.57–2.46 and 2.28–2.08Ga, as well as two metamorphic events at ca. 1.90 and 1.85Ga.