Abstract: Background, aim, and scope The dry-hot valley is a unique and important natural landscape in south-west China, however, the evolutionary history of this landscape has not been clear for a long time. The loess-like sediment widely covering the bottom of the dry-hot valley can be used as stratigraphic records for solving this problem. To do this its provenance must be understood. In this article, based on the systematical analysis of the elemental and mineral composition between the loess-like sediments and its likely source such as ancient dammed lake sediments, overbank sediments and mountain red soil, the provenance of loess-like sediment has been determined in terms of composition similarity. Materials and methodsThe samples of loess-like sediments and their possible provenance (including paleo-dammed lake sediments, overbank sediments and mountain red soil) are collected in the reach of Jinjiangjie, Yuanmou and Qiaojia in Jinsha River. The same type samples from different river reach are mixed uniformly and sieved over 2 mm screen for measure. The major elements and trace elements of samples are measured by Magix PW2403 X-ray fluorescence spectrometer (XRF) and X’Pert3 Powder x-ray diffractometer (XRD) is used for the determination of mineral composition of samples. ResultsThe analyze test results of major elements and trace elements indicate that among overbank sediments, mountain red soil and paleo-dammed lake sediments, which are possible provenance, the mountain red soil is the biggest difference in composition of elements from loess-like sediments in dry-hot valley of Jingsha River, while the paleo-dammed lake sediments is smallest. The X-ray diffraction pattern also shows that not only in terms of signal strength, but at the peak position, the paleo-dammed lake sediments are most similar to the loess-like sediments among the three potential sources.Discussion The results of comparative analysis of elements and minerals suggests that paleo-dammed lake sediments are major provenance of loess-like sediment in dry-hot valley of Jinsha River and the local red soil contribute little to the provenance. In fact, the similarity of element composition between ancient dammed lake deposits and loess like materials has been reported as early as a few years ago, but at that time the ancient dammed lake deposits were not been regarded as major provenance due to lack of data from other area or other possible provenance, such as red soil covering the mountains on both sides of dry-hot valley, to support. In addition, the phenomena that as long as there is loess-like sediment, the paleo-dammed lake sediments can always be found nearby, also confirms the inherent relation between the paleo-dammed sediments and the loess-like materials.Conclusions Among the three-possible provenance, the dammed lake sediments are most similar to the loess-like sediments in the Jinsha River Dry-Hot Valleys in terms of elemental and mineral composition, which shows that dammed lake sediments may be the main source of the loess sediments in the Jinsha River Dry-Hot Valleys.Recommendations and perspectives Previous study show that the loess-like sediments in Jinsha River dry-hot valley has been deposited at last during the late Pleistocene. Determination of their provenance would benefit to reconstruct the evolutional history of dry-hot valley landscape, which is a major scientific issue in south-west China and is difficult to solve by stalagmites, tree ring records in this area.
Keywords: Loess-like sediments; Provenance; Elements and Mineral composition; Dry-hot Valleys of the Jinsha River