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Comprehending heavy mineral composition of the sandy land in Northeast China (NESL) is of great significance for interpreting generation, pathways, source and geochemistry of sediments in this area. To this end, the fine-grained (<63 μm) aeolian-fluvial sediments and loess deposits, which were taken from the Onqin Daga Sandy Land, the Horqin Sandy Land, the Hulun Buir Sandy Land and the Songnen Sandy Land, and from the downwind loess section (L1), respectively, were analyzed to construct the heavy mineral data set of NESL source and sink and to evaluate feasibility of the heavy mineral method in tracing the source of aeolian dust in Northeast China. Additionally, the <63 μm, 63–125 μm and 125–250 μm fractions of the fluvial sands from the different Balan River reaches having a same source, were analyzed to valuate the impact of the river transport-sedimentation process on the heavy mineral composition. The results show that the NESL shows moderate similarities in the heavy mineral composition, with ilmenite, epidote, zircon and amphibole as the primary minerals. In the source-to-sink system in the NESL, limited by sedimentary differentiation, post-deposition alteration and similar source material composition, the heavy mineral composition of the loess and that of sandy-land sources does not well correlate, indicating single heavy mineral method is incapable of unequivocally detecting loess sources when not considering the physical geographical conditions. The sediments in the different Balan River reaches show clear diversities and grain-size dependency in heavy minerals composition, indicating the river transport-deposition processes exert a clear control on the heavy-mineral composition in the sediment downstream. Both a wide grain-size window and more numbers of samples are needed to obtain a complete heavy-mineral picture in the source area. [ABSTRACT FROM AUTHOR]

• Potential sources of the Harbin loess were quantitatively tracked. • The source of the Harbin loess changed during the glacial-interglacial cycles. • The source of the Harbin loess varied before and after ∼ 250 ka. • The source shifts caused by the variable wind regimes and climate oscillations. Provenance studies are critical for the paleoclimatic reconstruction of loess. However, very little information is available about the provenance variations of the loess in the monsoon boundary zone, limiting our understanding of aeolian dust dynamics, the evolution of atmospheric circulation and driving mechanisms on the glacial-interglacial timescale. To this end, the integration of grain size end-member modeling, machine learning, sediment fingerprinting and wavelet transform analysis is performed for the Harbin loess in Northeast China to understand the long-term provenance variations, atmospheric circulation evolutions and forcing mechanisms. The results show the Harbin loess comprises three grain size end-members, EM1 (7.81 μm), EM2 (27.2 μm) and EM3 (54.41 μm), and they correspond to the background of atmospheric dust, the intensity of the southwesterly and of the East Asian Winter Monsoon (EAWM), respectively, indicating the three transport dynamics of dust delivered to this region. The quantitative source reconstruction indicates that the loess experienced the dramatic source variations, characterized by an abrupt termination of the dust contribution from the Hulun Buir Sandy Land at ∼ 250 ka, and by variations in the relative contribution of the dust sources (i.e., Songnen Sandy Land, Horqin Sandy Land, Onqin Daga Sandy Land, and to a lesser extent, Hulun Buir Sandy Land) during the glacial-interglacial cycles. The comparisons between the indicators, e.g., EM2, the deep-sea oxygen isotopes and the rate of dust accumulation in the North Pacific, combined with wavelet transform analysis indicating a dramatic shift of orbital cycles from the significant 100-kyr and 41-kyr cycles to a weakened 100-kyr cycle, suggest that the weakened EAWM induced by both reduced the Northern Hemisphere ice volume and summer solar radiation, accounted for a termination of the Hulun Buir Sandy Land as the loess source. However, the change in wind regimes due to the glacial-interglacial cycles, and climate change (e.g., enhanced aridification) are the dominant forcing for the variations in the relative contribution of the dust sources to the Harbin loess. [ABSTRACT FROM AUTHOR]

• Elaborate Sr-Nd isotopic composition of the Northeast Sandy Land were constructed. • Nd isotopic composition exhibits significant dependency on time effect. • Nd isotopic composition shows clear grain size-dependent variability. • Sr-Nd isotopic values show enrichment in the coarse-grain fraction. The Sr-Nd isotopic study of the Northeast Sandy Land (NESL), China is of great significance for a thorough understanding of the dust system in this area. The 162 bulk (<63 μm) and 86 size-fractioned samples of surface eolian sands and river sands in the NESL are very suitable to be added to the elaborate Sr-Nd isotopic composition dataset. The results are as follows. The Nenjiang River drainage system (NR) in the Songnen Sandy Land (SNSL) and the Hulun Buir Sandy Land (HLSL) are characterized by more radiogenic Nd values relative to the other areas within the NESL whereas the Onqin Daga Sandy Land (ODSL), the Horqin Sandy Land (HQSL) and the Songhua River drainage system (SR) exhibit a clear overlap of Sr-Nd isotopic composition. Nd isotopic composition (especially in the ODSL) exhibits significant dependency on time effect, indicating instability of geochemical composition in the dust source areas. Sr isotopic composition is slightly affected by grain size with very small variations of size-separated 87Sr/86Sr values, yet Nd isotopic composition exhibits clear grain size-dependent variability. The substantial proportion of Sr-Nd isotopic values show enrichment in the coarse-grained fraction, which is accounted for by source-rock control. Both the HLSL and the NR to the northwest of Harbin play very little role in contribution to eolian dust deposits in the Northeast Plain, either in the geological past or now, whereas Sr-Nd geochemical composition alone is insufficient to unequivocally distinguish exact provenance of the eolian dust deposits in this region. The integrated consideration, as expected, revealed the derivation of the eolian dust deposits. The eolian loess and the modern dust-storm deposits in Harbin share significantly different source areas: Harbin loess is the product of spring dust-storm weather and has a mixed source with the SR being the main dust contributor, whereas 2011 Harbin dust-storm deposits were derived from the ODSL and beyond which also provided minor amounts of fine dust particles to Harbin loess. [ABSTRACT FROM AUTHOR]