渭河流域沉积矿物组合定量分析及示踪

扫描电镜定量分析沉积物矿物组合的方法，可以快速准确得到大量详细的矿物组合、矿物颗粒大小和岩屑组成等信息。尝试利用这一方法，研究渭河流域现代河流样品的矿物组合和沉积物碎屑组分，探究其在沉积物源示踪上的应用。研究表明，渭河流域现代沉积重矿物组合主要以角闪石、帘石类矿物和石榴石为主，不同区域沉积物矿物组合通过主成分分析图表（Principal Component Analysis，PCA）可以较好地区分开。轻矿物以石英和长石为主。碎屑组分石英—长石—岩屑（QFL）三角图解显示渭河干流和流经鄂尔多斯高原的两大主要支流北洛河和泾河的沉积物碎屑组分，主要位于再旋回造山带区域；而北秦岭山前河流沉积碎屑组分则主要位于岩浆岛弧区域。这一结果符合区域地质构造背景，表明扫描电镜定量分析手段可很好地应用于沉积物碎屑组分QFL三角图解、重矿物组合物源示踪研究。

Quantitative Analysis of the Clastic Mineral Composition in Sediments from the Weihe River Basin by Scanning Electron Microscope and Its Implication for Provenance

Quantitative analysis of sediment mineral composition using a scanning electron microscope （SEM） can quickly and accurately obtain a large amount of detailed information， such as mineral composition， mineral particle size， and rock debris composition. This study uses this method to examine the mineral and sediment clastic compositions of modern river samples in the Weihe River Basin and explore the possibility and reliability of its application in sediment tracing. The results indicate that the light minerals in the modern river sediments from the Weihe River Basin are primarily quartz， feldspar， and lithic fragments The quartz-feldspar-lithis （QFL） triangle diagram shows that the sediment components in the mainstream of the Weihe River and its two main tributaries， the Beiluo and Jinghe Rivers， flowing through the Ordos Plateau are the recycled orogen provenance， while the sedimentary clastic components of the rivers in the piedmont of the North Qinling Mountains have a magnetic arc provenance. This result is consistent with the regional geological tectonic background. The heavy mineral assemblages of sediments in the study area are primarily amphibole， epidote， and garnet. The mineral components of sediments in different areas can be distinguished by Principal Component Analysis （PCA）. This study shows that the SEM quantitative analysis method can be used in QFL triangulation of sediment clastic components and tracing of heavy mineral sources.