Neoarchean to Palaeoproterozoic tectonic evolution of the Trans‐North China Orogen, North China Craton: Evidence from zircon U–Pb geochronology, Lu–Hf isotopes, and geochemistry of the Zanhuang Complex

Abstract

Research on the Zanhuang Complex has been one of the hotspots in the Neoarchean–Palaeoproterozoic tectonic evolution of the Trans‐North China Orogen (TNCO) in the North China Craton (NCC). Here, we present data from petrology, geochemistry, zircon U–Pb geochronology, and Lu–Hf isotopes on a suite of granite, diorite, TTG gneiss, and amphibolite in the Zanhuang Complex to characterize these rocks and understand their genesis. Zircon U–Pb data yield magmatic ages of 2,607 Ma for granite, 2,599 Ma for diorite and 2,561 Ma for TTG gneiss, with subsequent thermal event ages of 2,530 and 2,471 Ma. Lu–Hf isotopes show εHf(t) values ranging from 0.04 to 7.11 and crustal model ages of 2,700–3,100 Ma for the diorite, indicating a Meso‐ to Neoarchean mantle source with minor input of crustal components. The granite and TTG gneiss have the characteristics of volcanic‐arc granite, with low Sr/Y and (La/Yb)N, high Cr and Ni contents, positive Pb and K anomalies and negative Nb, Ta, P, and Ti anomalies. The amphibolite and diorite are similar to island arc basalt, with low K2O, Sr/Y, (La/Yb)N, and high FeOT, positive Pb anomaly, negative Nb, Ta, and Ti anomalies and absence of obvious Ce anomaly. These signatures indicate that these rocks were likely formed in a subduction setting. We have proposed a model of subduction–collision process in the TNCO, including subduction at ca. 2.70–2.55 Ga, arc–continent collision at ca. 2.55–2.45 Ga, extension and rifting at ca. 2.30–2.05 Ga, and continent–continent collision at ca. 1.90–1.75 Ga. Our results are consistent with the previous models on the tectonic evolution in the NCC and provide further insights into the Neoarchean–Palaeoproterozoic tectonic history of the craton.