An early Precambrian “orogenic belt” exhumed by the Phanerozoic tectonic events: A case study of the eastern North China Craton

• Published in: Earth-science reviews 2023-06, Vol.241, p.104416, Article 104416
• Main Authors: Zhao, Lei, Zou, Yi, Liu, Pinghua, Sun, Weiqing, Zhang, Rucheng, Zhou, Ligang, Zhai, Mingguo
• Format: Article
• Language: English
• Subjects: Archean–Paleoproterozoic terrane; Crustal profile; Exhumation; Jiaobei Terrane; Spatial variation; Sulu orogenic belt
• ISSN: 0012-8252
• DOI: 10.1016/j.earscirev.2023.104416

The operation of early plate tectonics is evidenced by belt-like occurrences of some Neoarchean–Paleoproterozoic (ca. 2.7–1.8 Ga) high-grade basement rocks in ancient continental blocks. Studies on the continental evolution of the North China Craton defined Paleoproterozoic mobile/orogenic belts in this continental block, which are usually regarded as solid evidence for the operation of plate tectonics during the Paleoproterozoic. However, if considering subsequent tectonic overprinting, then whether the current occurrences of these mobile belts can represent the primary tectonic geometry remains unclear. The high-grade Jiaobei Terrane is centrally located within one such Paleoproterozoic mobile belt, namely the Jiao–Liao–Ji mobile belt of the eastern North China Craton. Archean–Paleoproterozoic basement rocks are well preserved in this terrane and its multiple episodes of metamorphism are similar in age with those of the other Paleoproterozoic mobile belts of the craton. Additionally, Phanerozoic tectonothermal overprinting in this terrane also widely influenced much of the whole North China Craton. Most importantly, the basement rocks occurring in different regions of this terrane exhibit different metamorphic grades. Therefore, this terrane is ideal for identifying how the high-grade basement components, after repeated episodes of exhumation, were finally emplaced on the surface in the Phanerozoic. The Archean–Paleoproterozoic lithologies of the Jiaobei Terrane mainly consist of Archean tonalite–trondhjemite–granodiorite gneisses (TTGs) and Paleoproterozoic meta-volcanosedimentary rocks, as well as a small amount of Paleoproterozoic granitoids. The Archean TTGs occupy the central part of the Jiaobei Terrane and exhibit three episodes of magmatism at ca. 2.9 Ga, ca. 2.7 Ga, and ca. 2.5 Ga, respectively. The Paleoproterozoic meta-volcanosedimentary sequences are further divided into the Jingshan Group and the Fenzishan Group, which mainly occur in the southern and northern margins of the Archean gneisses, respectively. Despite this division, both groups have similar protoliths and geochronological frameworks. The Jiaobei Terrane was subjected to two episodes of high-grade metamorphism during the Neoarchean (ca. 2.57–2.46 Ga) and the Paleoproterozoic (ca. 1.98–1.78 Ga). Although the Neoarchean metamorphism has been identified in many places of the Jiaobei Terrane, its geological implications are equivocal because of pervasive and strong Paleoproterozoic me