Comparative analysis of heavy mineral characteristics of sediments from the Huanghe River and the Changjiang River based on the multiple-window grain size strategy

摘要

Identification of detrital heavy minerals was carried out using a multiple-window grain size strategy on 25 representative sandy-silt sediment samples from the estuaries of the Huanghe (including the abandoned Huanghe River) and Changjiang Rivers, with each sample divided into 6-9 fractions (for a total of 196 sub-samples) at 0.5 Phi intervals. After characterization of the samples with respect to the abundance of each mineral species, the mean values of content were determined as 37.7% amphiboles, 23.8% Fe-metallic minerals, and 14.4% stable minerals, corresponding to 7.1% garnet, 1.8% apatite, and 1.2% zircon, in the Huanghe River samples. In comparison, the Changjiang River samples were characterized as 54.9% amphiboles, 14.1% Fe-metallic minerals, and 6.5% stable minerals, with 1.7% garnet and 3.0% sphene. The ratio of unstable to stable mineral classes (UM/SM) in the silt sediments of the Huanghe River ranged from 2.3-6.8, the value of epidote group/stable minerals was 0.7-2.3, and the ratio of garnet to sphene (Grt/Spn) ranged from 1.2-2.7. The Changjiang River's corresponding mineral ratios were 6.0-22.8, 2.3-5.2, and 0.4-1.3, respectively. The identification data reveal that the main heavy minerals and stable minerals differ substantially, suggesting that mineral profiling could be used for source identification and differentiation of sediments originating from these two rivers. The multi-particle heavy mineral method better reflects the samples' entire characteristics than single-particle analysis (3-4 Phi), thus providing a more reliable end-element index for the distinction between sediments of the Huanghe and Changjiang Rivers.