Early Cambrian evaporite deposits in the North China Craton and their event stratigraphic, paleogeographic, and paleoenvironmental implications

Abstract

Evaporites are climate-sensitive sedimentary deposits with event stratigraphic, paleogeographic, and paleoenvironmental significance. The Early Cambrian is characterized by early evolution of animal and extensive evaporite deposits at the end. Widespread evaporite deposits were developed in the lower Cambrian succession in the North China Craton (NCC), which could provide critical constraints on the age of evaporite-bearing strata, the reconstruction of paleogeographic evolution, and the paleoenvironmental change of the NCC during the Early Cambrian. In this study, we systematically synthesized the geographical and stratigraphic distributions of the Early Cambrian evaporite deposits in the NCC based on field collections and published data. The results show that the Early Cambrian evaporite deposits in the NCC mainly include gypsum, halite pseudomorph, and gypsum breccia. They have been found in two sets of reddish layers and geographically distributed in the Jiao-Liao-Xu-Huai region and western Henan region. Integrated evidence of biostratigraphy, chemostratigraphy, and detrital zircon chronology constrains the age of these evaporite deposits within the Cambrian Series 2, Stage 4 (ca. 514–509 Ma). Consequently, these late Early Cambrian evaporite deposits represent drought events that can act as regional event stratigraphic markers to constrain the age of the evaporite-bearing strata near the Great Unconformity and also suggest that the paleogeographic position of the NCC in the Cambrian Stage 4 may be located between 20°N–30°N near the western Gondwana with northwest-southeast orientation. Additionally, the hot-arid paleoclimate evidenced by evaporite deposits may be the environmental factors for the decline of benthic organisms in the NCC in the late Early Cambrian.