Sedimentological, geochemical, and geochronological constraints on the origin of the Neoproterozoic Luoquan Formation at the Southern Margin of the North China Craton

During Neoproterozoic global climate changed drastically and associated glacial deposits have been found worldwide. However, there are few such records at the southern margin of the North China Craton (NCC), limiting the comparison of the glacial deposits with other parts of the world. In this study, five sections of the Neoproterozoic Luoquan Formation were investigated in a systematic field survey using traditional sedimentology, geochemistry, and geochronology methods to reveal genesis, paleoclimate, paleoenvironment, and provenance of the Luoquan Formation. The results reveal depositional evidence for glaciation, such as sedimentary characteristics of massive diamictites, bedded and weakly bedded diamictites, sandstone lenses, lonestone-bearing siltstone, glacial relics, and striated pavements. All geochemical indicators show positive trends, such as in the values of Fe/Mn, Mg/Ga, Sr/Ba, sigma REE, and Cu/Zn. The zircon U-Pb data of the stable sandstone strata in the Luoquan Formation show a main peak at 2494 million years (Ma) and secondary peaks at 1656, 2100, and 2233 Ma. Sedimentary characteristics, glacial relics, changes in geochemical values, and the provenance age of detrital zircons suggest that the Luoquan Formation represents glacial meltwater deposits that eroded the nearby strata in a gradually warming environment. The direction of glacier migration, from north to south, revealed that the NCC deposition process occurred in the late Neoproterozoic.

Automated summary

During the Neoproterozoic, global climate changed dramatically, leading to the discovery of glacial deposits worldwide. This study focused on investigating the Neoproterozoic Luoquan Formation in the southern margin of the North China Craton, revealing evidence of glacial meltwater deposits eroding nearby strata in a gradually warming environment. Sedimentary characteristics, glacial relics, changes in geochemical values, and the provenance age of detrital zircons all support the conclusion that the NCC deposition process occurred in the late Neoproterozoic with glacier migration from north to south.