Application of Elemental Geochemistry in Provenance Analysis of Paralic Tidal Flat Sedimentary Systems: A Case Study from the Shanxi Formation, Southern North China Basin

The Southern North China Basin (SNCB), located in the southeastern part of the North China Plate, encompasses the study area within its central region. Investigating the sedimentary provenance of the Shanxi Formation in this area not only provides critical constraints for resolving the sedimentary-tectonic environment of the SNCB but also holds significant implications for the comprehensive evaluation of reservoir quality across the entire basin. This study focuses on sandstones, siltstones, and mudstones of the Shanxi Formation from three boreholes in the central SNCB. Petrological and geochemical analyses were conducted on transitional marine-continental facies clastic rocks to determine material sources and tectonic settings of the provenance area using geochemical and petrological characteristic parameters. The results indicate that: (1) In provenance studies of transitional marine-continental facies clastic rocks, trace and rare earth elements exhibit higher sensitivity compared to major elements; (2) Based on major and trace element compositions and ratios, the Shanxi Formation in the study area is interpreted as a nearshore, freshwater, oxygen-poor to oxygen-rich, weakly reducing to weakly oxidizing shallow marine depositional environment; (3) The tectonic setting is classified as an Andean-type continental margin, with detritus predominantly derived from uplifted continental island arcs, supplemented by contributions from uplifted active continental margins and ancient passive continental margins; (4) The Shanxi Formation clastic rocks exhibit diverse provenance sources, primarily originating from the North Qinling region and the North China Craton.