Nature and evolution of the lower crust in the eastern North China craton: A review

• Published in: Earth-science reviews 2013-07, Vol.122 (5), p.1-9
• Main Authors: Jiang, Neng, Guo, Jinghui, Chang, Guohu
• Format: Article
• Language: English
• Subjects: Continental dynamics; diorite; granite; Granulite terrain; Igneous rocks; Lower crustal xenolith; Magma; Magma mixing; melting; Mesozoic igneous rocks; Metamorphism; mixing; North China craton; silica; Sr–Nd–Hf isotopic composition; volcanic rocks; zirconium
• ISSN: 0012-8252; 1872-6828
• DOI: 10.1016/j.earscirev.2013.03.006

In this paper, published data for granulite terrain rocks exposed at the surface, lower crustal xenoliths, and Mesozoic intermediate-felsic igneous rocks from the eastern North China craton (NCC) are integrated to constrain the nature and evolution of the lower crust in this area. U–Pb zircon dating shows that the protolith ages for most of the granulite terrain rocks are 2500 to 2600Ma and that many of them experienced 1800–1900Ma metamorphism. Lower crustal xenoliths entrained in volcanic rocks with ages varying from ~460 to ~10Ma suggest that the lower crust is dominated by Neoarchean rocks, although there may be minor rocks with ages of Meso- to Paleoarchean (>3000Ma), ~45Ma and possibly ~1900Ma locally. The Mesozoic intrusive rocks, although varying from diorite to granite and spanning from Triassic to Cretaceous, contain ~2500Ma inherited zircons and have magmatic zircons with Hf crust model ages (TDMHf, C) ages of 2500–2700Ma and whole-rock Sr–Nd isotopic compositions falling within the field of the granulite terrain rocks, pointing to their derivation by the melting of Neoarchean lower crust. The combined data for the granulite terrain rocks, lower crustal xenoliths and Mesozoic intermediate-felsic igneous rocks indicate that the present lower crust is dominated by rocks with Neoarchean ages and is intermediate to mafic in composition (i.e., SiO2