Episodic tectonothermal events of the western North China Craton and North Qinling Orogenic Belt in central China: Constraints from detrital zircon U–Pb ages

Abstract

Detrital zircon U–Pb geochronology serves as a proxy to study of crustal evolution and provenance discrimination. In order to unravel episodic tectonothermal events and their tectonic relationship between the North China Craton (NCC) and North Qinling Orogenic Belt (NQOB), detrital zircons from modern river sands and metasedimentary rocks were collected and dated by LA-ICPMS. Although the western NCC (Ordos block) is covered by Paleozoic–Cenozoic basin sediments, the U–Pb dating results show that the age populations of detrital zircons from the western NCC present prominent U–Pb age peaks at 2475Ma and 1850Ma, which indicates the western NCC (Ordos block) also has early Precambrian basement similar to the eastern and central craton. In addition, a significant number of early Paleozoic (520–400Ma) zircons have been found in the western NCC, which is quite different from the eastern NCC and is considered to be related to the collision between the NQOB and the NCC.The age spectra of detrital zircons from the NQOB presents a complex age pattern, which reveals four major age groups of Neoarchean (2.6–2.4Ga), Neoproterozoic (1.0–0.85Ga), early-middle Paleozoic (450–350Ma) and early Mesozoic (250–170Ma). As indicated by the U–Pb isotopic data that the NQOB could be an independent terrane at least prior to the Neoproterozoic and once a portion of the Grenville orogenic belt during the 1.2–0.8Ga with a peak of ∼1.0Ga. In other words, the NQOB has its unique geological evolution history obviously different from those of the NCC and the Yangtze Craton. The complete collision between the NQOB and the NCC perhaps took place at Paleozoic (450–400Ma).