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分析单颗粒碎屑锆石组成特征是示踪黄土源区、进而探讨粉尘物质形成和搬运机制的有效手段.本文介绍了利用碎屑锆石内部结构特征、微量元素、锆石U-Pb年龄谱和Hf同位素组成进行物源示踪的原理和方法,并对科尔沁沙地及其外围黄土末次冰期样品进行了碎屑锆石示踪研究.结果显示,科尔沁黄土碎屑锆石U-Pb年龄谱主要为2600～2300,2100～1600和600～100Ma.2600～2300Ma的锆石-Hf(t)值偏正(-3.4～8.7),2100～1600Ma锆石-Hf(t)值偏负(-10.1～6.8),600～100Ma锆石-Hf(t)值范围较宽(-21～15.9).黄土沉积的锆石U-Pb年龄谱和Hf同位素组成与科尔沁沙地相同,但与黄土高原和中西部沙漠有很大差异,说明末次冰期时科尔沁沙地是其外围黄土的主要源区.通过与周围构造单元对比,发现2600～2300,2100～1600,600～100Ma且-Hf(t)为负值的锆石可能来源于华北克拉通东北部,600～100Ma且-Hf(t)为正值的锆石可能来源于中亚造山带东部.半定量估计表明:二源区对科尔沁沙地和外围黄土物质的贡献约各占一半.
It is an effective method to trace the formation of loess and tracing the source region of loess so as to explore the mechanism of formation and transport of dusts.This paper introduces the use of detrital zircon internal structure characteristics, trace elements, zircon U-Pb age spectrum And Hf isotopic composition tracing, and detrital zircon tracer studies were carried out on the last glacial samples of Horqin sandy land and its surrounding loess. The results show that zircon U-Pb ages of Horqin loess detrital zircons The values of zircon-Hf (t) values of -2600-2300, 2100-1600 and 600-100 Ma, respectively, ranged from -3.4 to 8.7 and from -216 to -1600 Ma, 10.1 ~ 6.8), and a wide range of zircon (-21 ~ 15.9) in 600 ~ 100 Ma zircon U-Pb ages and Hf isotopic composition of the zircon deposits are the same with those of Horqin sandy land, Which shows that the Horqin sandy land is the main source area of the loess in the end of the last glacial period.Comparing with the surrounding tectonic units, it is found that-26700, 2300, 2100-16000, 600-100 Ma and -Hf (t) Zircons that are negative may originate from northeastern North China craton, and zircons with a positive value of -Hf (t) of 600 ~ 100Ma may come . In the eastern part of the Central Asian Orogenic Belt semi-quantitative estimates show that: the contribution of the second source region Horqin sandy loess and peripheral material about half and half.