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汉江流域位于黄土高原南侧,属中国南北气候的过渡区域,其重矿物组成对区域沉积物物质来源与演化研究具有重要意义。运用强磁选、重液分离法等技术手段将汉江上游谷地黄土沉积物中的重矿物提取出来,在双目显微镜和偏光显微镜下测定其含量和特征。结果表明:(1)汉江黄土重矿物有22种,其中角闪石、磁铁矿、钛铁矿等矿物为优势矿物,占重矿物总量的60%以上;稳定矿物约占重矿物总量的47.95%,是汉江黄土最主要的矿物组合。(2)典型黄土和古土壤中重矿物种类相同,但含量有一定差异,马兰黄土(L1)相较古土壤(S0)不稳定矿物含量较高,稳定矿物含量较低;(3)汉江黄土与北侧黄土高原黄土相比重矿物种类相似,稳定性组合分布一致,但汉江黄土稳定性矿物含量较高,不稳定性矿物含量较低。这些特征说明:(1)汉江上游地区古土壤和黄土物质来源一致,古土壤S0在物质组成上继承了黄土,是黄土高度风化的产物;(2)汉江谷地黄土和黄土高原风成黄土两者的物源区一致,但汉江地区黄土受到较黄土高原地区强的风化成壤作用。
The Hanjiang River Basin is located in the south of the Loess Plateau and belongs to the transitional area of climate between North and South of China. Its heavy mineral composition is of great significance for the study of the source and evolution of sediment in the region. The heavy minerals in the loess deposits in the valley of the upper reaches of the Hanjiang River were extracted by means of strong magnetic separation and heavy liquid separation, and their contents and characteristics were determined under a binocular microscope and a polarized light microscope. The results show that: (1) there are 22 kinds of heavy minerals in loess of Hanjiang River, in which amphiboles, magnetite and ilmenite are the dominant minerals, accounting for more than 60% of the total heavy minerals; the stable minerals account for about the total heavy minerals Of 47.95%, is the most important mineral assemblage of the Han River loess. (2) The types of heavy minerals are the same in typical loess and paleosol, but the contents are different. The content of unstable minerals in Malan loess (L1) is higher than that in ancient soils (S0), and the content of stable minerals is low. (3) Compared with the loess on the north side of the Loess Plateau, the heavy mineral species are similar and the stability combination distribution is consistent. However, the stability of the Hanjiang loess is high, while the content of unstable minerals is low. These characteristics indicate that: (1) the source of ancient soils and loess in the upper reaches of the Hanjiang River are consistent with each other, and the ancient soils SO inherited loess from the composition of the loess and are highly weathered products of loess; (2) both loess in the Hanjiang River valley and aeolian loess in the Loess Plateau But the loess in Hanjiang River area is stronger than that in the Loess Plateau.