Constraints on the growth and evolution of continental crust in the NE Cathaysia Block: insights from detrital zircon U–Pb ages and Hf–O isotopic analyses in Tingjiang sediments Available to Purchase

Fluvial detrital zircons provide crucial insights into crustal evolution in the early Precambrian. We used U–Pb geochronology and the Hf–O isotopic compositions of detrital zircons from the Tingjiang River to determine the provenance and continental crustal evolution of the NE Cathaysia Block. The zircon U–Pb ages show seven major populations at 177–105, 262–200 and 520–376 Ma, with striking peaks at c. 422, 775–606, 1457–836, 2042–1710 and 2661–2300 Ma, corresponding to documented tectono-thermal events in the South China Block. Episodic magmatism was the response to the formation and break-up of the Columbia and Rodinia supercontinents. The episode at 422 Ma matches with the ages of widespread early Paleozoic intraplate orogenic events in the South China Block. The isotopic signatures of Hf and O in the detrital zircons indicate that the majority of the Precambrian zircons likely originated from remelted ancient continental crust, with contributions from juvenile mantle-derived magmas. The Phanerozoic zircons, by contrast, were formed through the partial melting of recycled crustal material. Analysis of crustal growth rates, based on the two-stage Hf model ages, suggests a significant presence of juvenile crustal growth during the Paleoproterozoic era. Specifically, it is estimated that c. 40 and 90% of the present crust within the NE Cathaysia Block was formed at c. 2.3 and 1.6 Ga, respectively.