Detrital zircons from Paleoproterozoic (meta-)sedimentary rocks on the northern margin of the North China Craton and tectonic implications

Abstract

<p>The Paleoproterozoic strata on the northern margin of the North China Craton (NCC) comprise a relatively intact low-grade (meta-)sedimentary sequence, but whether there are breaks in the sequence and the tectonic setting in which the sequence was deposited are uncertain. In this study, we use zircon U-Pb dating and Hf isotopic analysis to constrain the provenance, depositional age, and depositional environment of the Paleoproterozoic strata, and discuss the likely tectonic setting of sedimentation on the northern margin of the NCC during the Paleoproterozoic. The distribution of detrital zircon ages shows that the lower <em>meta</em>-feldspathic sandstone unit of the Paleoproterozoic sequence was deposited after ca. 2.2 Ga, whereas the maximum depositional age of (meta-)quartz siltstone and quartzites were around 1.89 Ga and at from ca. 1.86 to 1.81 Ga, respectively. Integration of our new U–Pb and Hf isotope data with literature data from other regions of the NCC, allow us to demonstrate that the Paleoproterozoic strata experienced a depositional environment between ca. 2.2–1.81 Ga in an extensional basin system. This suggests that the northern margin of the NCC evolved from an extensional tectonic setting, possibly related to slab rollback. Subsequently, the Paleoproterozoic sequence was affected by a ∼1.8 Ga metamorphic event to form these (meta-)sedimentary rocks in the region.<span> </span></p>