Mineralogical and elemental geochemistry constraints on provenance evolution of sediments in the lower reaches of the Shichuan River, Shaanxi Province, China

Abstract

The Shichuanhe River, a major tributary of the lower Weihe River, is situated in Xi’an, Shaanxi Province, China. It holds significant information regarding the evolution of the Northern Weihe River, making its study crucial for understanding environmental changes in the region. Despite its importance, research on the Shichuanhe River basin has thus far been primarily focused on riverbank construction, with limited exploration of its sediment characteristics. Although river sediments hold potential for guiding agricultural practices in the area, comprehensive studies on their composition and provenance remain scarce. To address this gap, a systematic sediment sampling campaign was conducted in the lower reaches of the Shichuanhe River, and detailed mineralogical analyses were performed. The results show that the sediment is predominantly composed of detrital quartz and feldspar (albite and orthoclase), with heavy minerals constituting approximately 10%–12% of the total sediment volume. The analysis of the heavy mineral assemblage reveals an absence of significant contributions from igneous rocks in the sedimentary profile. Furthermore, the distribution patterns of major, trace, and rare-earth elements in the Shichuanhe River’s argillaceous sediments exhibit similarities to those found in the Weihe River’s sediments. Elemental fractionation patterns suggest that the Shichuanhe River sediments are primarily derived from Loess Plateau sediments, aligning with findings from both the Weihe River and the middle reaches of the Yellow River.