Study On Distribution Of Palygorskite In The Zhaojiachuan Section In Xifeng, Gansu Province And Its Paleoclimate Significance

The eolian sequence in Chinese Loess Plateau, including the Quaternary loess-paleosol sequence and Tertiary red-clay sequence, is an excellent continent paleoclimate proxy. In this paper, field emission scanning electron microscopy (FE-SEM),high resolution transmission electron microscopy (HRTEM)and X-ray diffraction (XRD)analysis of palygorskiteand dolomite samples of thedistribution and characteristicsof a systematic study on Zhaojiachuan red clay-loess-paleosol profile in Xifeng, Gansu Province. The major findings and conclusions are listed as the following:The fibrous palygorskite distributes in the red clay laminated shape mineral gap, or grow on the edge of the clay mineral chip. indicating sediment palygorskite has a role in the causes of autogenic, characteristics of a thin filamentous palygorskite crystals from the solution of crystal deposition The standard features of palygorskite-type. The distribution of palygorskite in zhaojiachuan profile have a very good coupling with other indicators.We suggest that the palygorskite changes are correlated with the uplift of the Qinghai-Tibet Plateau during Late Miocene and also coupled with the development of the Asian inland drought, in support of the Qinghai-Tibet Plateau uplift of the control of the East Asian monsoon wind into a heap of important control, Verify Late Pliocene climatic aridity beginning of the Loess Plateau, Pleistocene drought continues to intensify, palygorskite can be used as new mineralogical indicators of climate.The dolomite and the palygorskite paragenesis, the dolomite crystal is good, the surface is smooth, presents the model the tetrahedron shape. Dolomite is covered by palygorskite or fibrous palygorskite grows on the edge of dolomite, dolomite has typical autogenic characteristic. the entire section has dolomite distribution of red clay in zhaojiachuan profile. the different position dolomite content is different, the dolomite content's change curve and the carbonate curve have the very good coupling, the dolomite content curve and the magnetic susceptibility curve present the good inverse correlation, the magnetic susceptibility high value position dolomite content are few, the magnetic susceptibility low value position dolomite content are many. In the red clay's dolomite not only may take one good summer monsoon intensity vicarious proxy, moreover may also have the important instruction significance to the carbonate stable isotope research.