Source characteristics and paleoenvironment analysis of fine-grained sediments in the secondary terrace of Xining section of Huangshui River,Qinghai Province
The secondary terrace of Huangshui watershed in the Qinghai province was formed in the late Pleistocene.Element geochemical analysis of the fine-grained sediments in the upper part of the terrace can effectively explore the last glacial event of the Quaternary in the northeastern margin of the Qinghai-Tibetan Plateau.The sediments are mainly lithic sand,and its major element content is similar to that of Lanzhou Pleistocene Q3 loess.The analysis reveals that the sediments are mainly come from the felsic source area,upper crust,granite and loess areas,and have a trend of sediment recycling,indicating that the sediments in the study area may have experienced a secondary transport process:from the upper crust(felsic source area)to aeolian sediment(loess)to fluvial sediment,and its source area might be the Qaidam Desert.The chemical alteration index CIA value is from 59 to 64,and the composition variation index ICV value is from 1.43 to 2.10,indicating that the secondary terrane of Huangshui River was in a cold and dry environment during the deposition period,which is consistent with the previous sporopollen studies in this area.In the geotectonic background analysis result indicates that the tectonic background of sediment source of this study area is complex,and the East Kunlun orogenic belt on southern margin of the Qaidam Craton has obvious active continental margin and island arc attributes.The major tectonic uplifting events in the East Kunlun orogenic belt since the late Oligocene are highly consistent with the key time points of the Asian inland drying evolution.Therefore,we conclude that the initial source area of the sediments should be the East Kunlun orogenic belt.
paleo environmentprovenancemajor and trace elementssecondary terraceHuangshui River
万方数据
维普
