Eoarchean to Paleoproterozoic crustal growth and evolution of the southern North China Craton revealed by detrital zircon in the Paleoproterozoic Songshan Group

Abstract

Precambrian continental crust is window into Earth’s early history. The North China Craton (NCC) is one of the key regions worldwide to investigate the continuous crustal growth mechanism during early Earth. The Songshan Group is one of the best-preserved Paleoproterozoic sedimentary strata in the southern NCC, which is an ideal target to reveal the Precambrian continental crustal growth and evolution. However, the Songshan Group has received limited scientific scrutiny, both its depositional time and tectonic setting have not been well constrained. In this study, we present U-Pb detrital zircon ages and Hf-in-zircon isotopic data from sedimentary rocks of the Songshan Group. Based on the youngest single cluster of detrital zircons and the intrusion ages of Paleoproterozoic mafic dykes, the depositional age of the Songshan Group is constrained to the period of ca. 2.20–2.00 Ga. Rutiles from the two quartzite samples define lower intercept U-Pb ages of 1922–1912 Ma, suggesting the Songshan Group had undergone the final assembly of the NCC. U-Pb age spectra of the detrital zircons from the Songshan Group show multi-stage age clusters at ca. 3.84–3.33, 3.03–2.80, 2.80–2.60, 2.60–2.43 and 2.41–2.13 Ga, with two distinct peaks at ca. 2.70 and 2.52 Ga. The Precambrian basement in the southern NCC likely served as a proximal source for the clastics of the Songshan Group. The geochemical characteristics of detrital zircons indicate that they are derived from continental granitoid in a continental arc setting. Based on the sedimentology, provenance, geochronology, and geochemistry of the Songshan Group, we conclude that the group was deposited in a retroarc foreland basin during the period between ca. 2.20 and 2.00 Ga, which was positioned between an “Andean-type” continental margin arc and the Eastern Block. The U-Pb-Hf isotopic compositions of detrital zircons from the Songshan Group unveil two significant periods of continental crustal growth at ca. 2.95–2.60 and 2.60–2.45 Ga in the southern NCC, while the ca. 2.44–2.03 Ga zircons reveal a major episode of crustal reworking. Trace elements of detrital zircons indicate the increase of continental crustal thickness at ca. 2.80–2.70 and 2.58–2.50 Ga, with a maximum thickness at ca. 2.70 Ga, which are similar to that of modern orogenic belts. During and after the two periods, crustal thickness of the southern NCC was obviously shortened.