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系统采集了中国10个主要沙漠或沙地(塔克拉玛干沙漠、巴丹吉林沙漠、腾格里沙漠、柴达木沙漠、毛乌素沙漠、库布齐沙漠、古尔班通古特沙漠、浑善达克沙地、科尔沁沙地和呼伦贝尔沙地)样品,并在黄土高原西峰、环县和洛川剖面采集了马兰黄土(L1)样品。通过选择合适的粒级和样品处理方法,对样品酸不溶物进行了Nd和Sr同位素组成的测定。测定结果表明,中国10个沙漠或沙地的Nd同位素组成εNd(0)的变化范围大,为-1.2～-17.2。根据Nd同位素组成范围,10个沙漠或沙地的εNd(0)从高到低可以分为4个区域:A1:古尔班通古特沙漠和呼伦贝尔沙地(-1.2～-4.0);A2:浑善达克沙地和科尔沁沙地(-4.4～-7.0);B:塔克拉玛干沙漠、柴达木沙漠、巴丹吉林沙漠和腾格里沙漠(-7.4～-11.7);C:毛乌素沙漠和库布齐沙漠(-11.8～-17.2)。中国沙漠Nd同位素组成的分区性与中国北方的大地构造和山脉分布密切相关,并表明中国沙漠具有近源性,即沙漠物质主要来源于其邻近周围的山脉和基底岩石的风化侵蚀。通过对比,黄土高原黄土Nd和Sr同位素组成与柴达木沙漠和阿拉善高原的沙漠(腾格里和巴丹吉林沙漠)相同,而与其他沙漠不同。塔克拉玛干沙漠碳同位素组成为0.19‰～0.62‰;柴达木沙漠、巴丹吉林沙漠和黄土高原马兰黄土碳同位素组成都落在1.20‰～2.40‰之内。黄土高原马兰黄土碳同位素组成与柴达木沙漠和巴丹吉林沙漠相类似,而与塔克拉玛干沙漠不同。本次研究为Liuetal.(1996)的推论,即黄土高原黄土物质最终来源于青藏高原东北缘,提供了一个有力的同位素证据。
The system collected 10 major desert or sandy areas in China (Taklamakan Desert, Badain Jaran Desert, Tengger Desert, Qaidam Desert, Mu Us Desert, Khuzizi Desert, Gurbantunggut Desert, Hunshandak Sandland, Horqin sandy land and Hulunbeier sandy land) samples were collected and Malan loess (L1) samples were collected from Xifeng, Huanxian and Luochuan sections of the Loess Plateau. The Nd and Sr isotopic compositions of the acid-insoluble samples were determined by selecting the appropriate particle size and sample handling method. The results show that Nd isotope composition εNd (0) of 10 deserts or sandy lands in China varies widely, ranging from -1.2 to -17.2. According to the range of Nd isotope composition, εNd (0) of 10 deserts or sandy land can be divided into 4 areas from high to low: A1: Gurbantunggut Desert and Hulunbuir Sandy Land (-1.2 ~ -4.0); A2 : Hunshandake Sandy and Horqin Sandy Lands (-4.4 ~ -7.0); B: Taklamakan Desert, Qaidam Desert, Badain Jaran Desert and Tengger Desert (-7.4 ~ -11.7); C: And Kubuqi Desert (-11.8 ~ -17.2). The division of Nd isotopes in the desert of China is closely related to the tectonic and mountain distribution in the north of China and shows that the desert in China is near-sourced. That is to say, the desert material mainly comes from the weathering and erosion of nearby neighboring mountains and basement rocks. By comparison, the Nd and Sr isotopic composition of loess in the Loess Plateau is the same as that of the Qaidam Desert and the Alashan Plateau (Tengger and Badain Jaran Desert), but different from other deserts. The carbon isotope composition of the Taklimakan Desert is 0.19 ‰ ~ 0.62 ‰. The carbon isotopic compositions of the Malan Loess in the Qaidam Desert, Badain Jaran Desert and the Loess Plateau all fall within 1.20 ‰ ~ 2.40 ‰. The carbon isotope composition of the Malan loess in the Loess Plateau is similar to that of the Qaidam and Badanjilin deserts, but different from the Taklimakan Desert. This study is Liuetal. (1996) inference that the loess material on the Loess Plateau eventually came from the northeastern margin of the Qinghai-Tibet Plateau, providing a strong evidence of isotopes.