Early Cretaceous crust–mantle interaction linked to rollback of the Palaeo-Pacific flat-subducting slab: constraints from the intermediate–felsic volcanic rocks of the northern Great Xing'an Range, NE China. (24th September 2021)

• Record Type: Journal Article
• Authors: Jing, Jia-Hao; Yang, Hao; Ge, Wen-Chun; Dong, Yu; Ji, Zheng; Jing, Yan; Bi, Jun-Hui; Zhou, Hong-Ying
• Is Part Of: Geological magazine. Volume 158:Number 9(2021)
• Page Start: 1617
• Page End: 1638
• Publication Date: 2021-09-24
• Subjects: Early Cretaceous volcanic rocks -- crust–mantle interaction -- northern Great Xing'an Range -- petrogenesis -- rollback of the Palaeo-Pacific flat-subducting slab; Geology -- Periodicals; 551.05
• DOI: 10.1017/S0016756821000170
• Languages: English
• ISSNs: 0016-7568

Abstract

Abstract: Late Mesozoic igneous rocks are important for deciphering the Mesozoic tectonic setting of NE China. In this paper, we present whole-rock geochemical data, zircon U–Pb ages and Lu–Hf isotope data for Early Cretaceous volcanic rocks from the Tulihe area of the northern Great Xing'an Range (GXR), with the aim of evaluating the petrogenesis and genetic relationships of these rocks, inferring crust–mantle interactions and better constraining extension-related geodynamic processes in the GXR. Zircon U–Pb ages indicate that the rhyolites and trachytic volcanic rocks formed during late Early Cretaceous time ( c. 130–126 Ma). Geochemically, the highly fractionated I-type rhyolites exhibit high-K calc-alkaline, metaluminous to weakly peraluminous characteristics. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) but depleted in high-field-strength elements (HFSEs), with their magmatic zircons ϵHf ( t ) values ranging from +4.1 to +9.0. These features suggest that the rhyolites were derived from the partial melting of a dominantly juvenile, K-rich basaltic lower crust. The trachytic volcanic rocks are high-K calc-alkaline series and exhibit metaluminous characteristics. They have a wide range of zircon ϵHf ( t ) values (−17.8 to +12.9), indicating that these trachytic volcanic rocks originated from a dominantly lithospheric-mantle source with the involvement of asthenospheric mantle materials, and subsequently underwent extensive assimilation and fractional crystallization processes. Combining our results and the spatiotemporal migration of the late Early Cretaceous magmatic events, we propose that intense Early Cretaceous crust–mantle interaction took place within the northern GXR, and possibly the whole of NE China, and that it was related to the upwelling of asthenospheric mantle induced by rollback of the Palaeo-Pacific flat-subducting slab.