Heavy mineral analysis to identify sediment provenance in the Dan River drainage, China

Abstract

Identifying the provenance of sediments carried by modern rivers can provide information on earth surface processes and help us to interpret geological history more clearly. The types and distribution patterns of surface sediments deposited in river systems are determined mainly by the fluvial flux and weathering of the proximal source rocks. In this paper, analysis of the heavy mineral content of 99 surface sediment samples was used to identify the source of the sediments carried by the Dan River in China. The objectives of this study are to: (1) determine the characteristics and distribution of the sediments, and (2) identify and classify the various depositional areas according to their differing source areas. The Dan River is divided into the lower, middle, and upper reaches to investigate the spatial distribution of heavy minerals. The main minerals detected were amphiboles, pyroxene, epidote, garnet, tourmaline, zircon, apatite, rutile, sphene, anatase, pyrite, and ilmenite. Generally, ilmenite (0.7% to 69.1%), amphibole (0% to 93.6%), epidote (0% to 53.3%), garnet (0% to 36.7%) and pyroxene (0% to 42.0%) were the most frequent detrital heavy minerals in the studied river sections. The Dan River and its tributaries are characterized with respect to their heavy mineral assemblages and heavy mineral indexes. Six depositional areas are distinguished and classified as Depositional area A (the Laoguan, Qi, and Xian rivers), Depositional area B (the Qingyou and Wuguan rivers), Depositional area C (the Laojun River), Depositional area D (the upper reaches of the Dan River), Depositional area E (the Yinhua River), and Depositional area F (the Tao River). The provenance study indicated that the sediments were derived mainly from the proximal exposed rocks. Sediments in the middle reaches of the Dan River were derived from Depositional areas B, C, and E, whereas sediments in the lower reaches were derived mainly from the local rocks along the river. Similar heavy mineral assemblages were obtained from Danjiangkou Reservoir and Depositional area A, especially for the Laoguan River, indicating the significant influence of Depositional area A on the reservoir.