Determination Of Multi-scale Structure Of L₁/S₁ Loess-paleosol In Luochuan And Its Paleoenvironmental Significance

The Luochuan loess-paleosol profile is a good carrier of Quaternary climate change and can be used to reveal palaeoenvironment and palaeoclimatic changes in different geological periods.In the past,scholars have carried out a lot of research on the Luochuan section.Due to the limitations of testing techniques,there are not many studies on palaeoenvironmental paleoclimatic information on the short-time scale of the Luochuan section.If a new test method can be found,under the premise of preserving the microscopic morphology of the loess,it is possible to obtain several paleo-climate surrogate indicators that can be mutually verified from a test of one sample,which may provide a reconstruction for paleoclimate.New ideas and new methods.In this paper,combined with scanning electron microscopy and multi-scale microstructural method,the minerals of six loess samples of-L1,S1 and S0 of Luochuan were identified,and the particle size distribution characteristics of quartz,silicate minerals and carbonate minerals were extracted and analyzed.The extracted palaeoenvironmental information is compared with the research results of scholar Wu Naiqin adopted snails.The climate information extracted by the fossils is compared and combined with the previous research of the research group.The preliminary research results are:1)The paleoclimate environment information of the six sections is different.The content of each mineral on the hundred-year scale varies with the depth of the strata,that is,the palaeoenvironmental climate shows slight fluctuations;2)The palaeoenvironmental information extracted from,the six samples is basically consistent with the climatic information represented by the snail fossilsin the scholar Wu Naiqin's literature,that is,the six combinations of the palaeoenvironment from bottom to top are:the first combination has higher temperature and humidity;the second combination has improved the temperature and humidity,and there are great fluctuations during the period;the third combination zone has lower temperature and humidity than the second combination zone,the fourth combination has stronger monsoon,the climate is warmer,and the fifth combination has strong physical weathering and the climate is dry-cold.In the dry and cold,the sixth combination belt belongs to the Holocene period,the physical weathering is weakened,and the temperature and humidity are improved compared with the fifth combination belt.3)The silicate minerals and carbonate minerals have different peak sizes at 1?3(?m,and the content changes of the two in the 1?3?m fraction can be used as a substitute indicator for judging the paleoenvironmental climate.