Abstract:

In order to provide evidence for the Neoproterozoic great oxidation event on the northern margin of the North China craton, this paper investigates the sedimentary environment of the Nanfen Formation in Tonghua area. Petrology, geochemistry, and isotope geochemistry have been used on marlstones and shales to explore the tectonic setting, the degree of oxidation and reduction, and its response to the Neoproterozoic great oxidation event. The results show that the Nanfen Formation is composed of purple and yellow-green shales and marlstones, with marine sedimentary characteristics. Ni/Co ratio, V/Cr ratio, V/(V+Ni) ratio, Mo content, and total organic carbon content indicate that the sedimentary environment was oxidized during the forming period of Nanfen Formation. The oxidation degree of the Nanfen Formation fluctuated in the early evolutionary stage, and remained stable in the late stage. This proves that the Neoproterozoic great oxidation event occurred on the northern margin of the North China craton and responded well to the Neoproterozoic great oxidation event in South China.

Key words:  Tonghua area')">

 Tonghua area, Nanfen Formation, geochemistry, Neoproterozoic, Great Oxidation Event