Sedimentary sequence and evolutionary history of the Proterozoic basin at the southern margin of the North China Craton

Abstract

Aulacogen/Rift system deposits and tectonic-magmatic activities can be linked to the breakup of the Columbia supercontinent and have developed in the North China Craton (NCC). The Xiong'er Basin at the southern margin of the NCC consists of late Palaeoproterozoic-Neoproterozoic sedimentary strata and can be divided into three sedimentary sequences. Sedimentary Sequence I (1.83–1.75 Ga) consists of bimodal volcanic-sedimentary rocks of the Xiong'er Group with continental-marine facies and alluvial fan deposits of the Bingmagou Formation with local development. It represents the evolution of the intracontinental fault from initiation to decline. Sedimentary Sequence II (1.75–1.6 Ga) developed after the southern margin of the NCC entered a stable continental margin stage, is dominated by clastic rocks interbedded with local carbonate deposits, and fills the interior of the basin. As continuous transgression led to a transition in the sedimentary environment, sedimentary Sequence III (1.6–1.4 Ga) is dominated by carbonate strata that began to develop afterwards. This sequence is the caprock deposit in the Xiong'er Basin. Subsequently, tectonic uplift events occurred at the southern margin of the NCC, along with the start of exposure and denudation, which lasted for hundreds of millions of years. Moreover, abundant microbially induced sedimentary structures (MISS) with different morphological characteristics developed in clastic strata across different areas of the Xiong'er Basin. These structures effectively indicate sedimentary facies and their evolution, which facilitates the establishment of regional stratigraphic isochronous correlation and connection. For example, based on the time limit for the development of molar-tooth structures (MTS), the Hejiazhai Formation belongs to the Neoproterozoic strata, with a deposition time of 1.0–0.72 Ga. In conclusion, the study of the Precambrian sedimentary succession in the Xiong'er Basin, in response to the supercontinental breakup, can be useful in exploring the coupling mechanisms between various geological events.