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Quaternary deposits of various types (lacustrine, desert sand, river, loess and loess-like deposits) from the southwestern Tarim Basin, North Tianshan, northeast China and the central Loess Plateau exhibit an is-an-element-of(Nd)(0) range from - 5 to - 12.8 and a Sm-147/Nd-144 range from 0.110 to 0.140. Their Nd-depleted mantle model ages are between 1.50 and 1.92 Ga, with a mean value of 1.7 Ga. Th/Sc ratios vary over a wide range from 0.1 to 2. Comparison of these geochemical signatures with those of the old Australian shales and modern Pacific Ocean dust suggests a continuous input of mantle-derived material into the crust over geological time. The deposits from the North Tianshan show clearly different chemical and isotopic features, with significantly higher Sm/Nd, high Nd-143/Nd-144, low Sr-87/Sr-86, and low La/Lu and Th/Sc ratios relative to those in the deposits from the other areas. This indicates a geological control on the local source, which has an overall young age and an enrichment of basic components.

The is-an-element-of(Ce)(0) values of two loess samples from the central Loess Plateau are + 1.8 and 3.9, corresponding to depleted mantle model ages of 2.2 and 3.4 Ga. Like the Rb-Sr system, the evolution of the La-Ce isotopic system in the crust may be to some extent decoupled from the Sm-Nd system, due to La/Ce fractionation by sedimentary processes.

The loess deposits and the desert sand are not distinguishable in isotopic composition, but show somewhat different chemical compositions. We conclude that the loess can have originated from desert processes, since the difference in the chemistry of the desert sand and loess may result from mineral sorting during desert processes and aeolian transportation. The loess deposits on the central Loess Plateau chemically and isotopically resemble the desert loess deposits in the southwestern Tarim Basin but do not resemble those of the North Tianshan. Accordingly, the loess on the plateau may have a source region in the Tarim Basin but clearly not in the North Tianshan.