A Study On Layered Silicate Minerals In Purple Strata And Soil Based On XRD

In purple rocks and soils, the texture, exchange/adsorption, deposition, weathering and material sources of soils, all of that depend on the types and relative quantity of layered silicate minerals (LSM). Therefore,it is very significant to study the types and quantity of purple rocks and soils.On the one hand, the quantity and stability of most LSM are well than other crystalline minerals, such as titanium, iron, manganese and other trace minerals in soil. The X-ray diffractometer (XRD) pattern of the sample is clear and small interference peaks after a simple treatment. Furthermore, the species of some LSM is very abundant, the same peak shapes will yield to disturb the determination, and thus it is necessary to take some specialized ways to distinguish these special minarals.On the other hand, it can realistically reflect the charactoristics of the purple rocks and soils while the change law was studying through their relative quantity. It is accureate to calculate their relative quantity and the law of original purple rocks and soil LSM can be described by K value method.Based on those theory and meaning, this study adopts different treatment methods to deal with standard mineral and purple rocks based on the XRD, the types, quantity,distribution and evolvement etc of purple rocks, soils and LSM for different ages in Chongqing were studied by field sampling, laboratory analyzing and data analyzing.(1) Based on the XRD, comparing the patterns of the standard LSM with of Badong purple mud rock by the different treatments, the results showed that the intensity of ray peak or distance between crystal and surface obviously changed by the conventional thermal gradient (320,550,600,720℃) for standard LSM (kaolinite, vermiculite and montmorillonite) can be easy to identify constituents; In the appraisal purple parent rocks Triassic badong group mudstone, according to standard of LSM thermal gradient treatment appraisal conditions, XRD based on the appraisal, clear identified LSM composition for chlorite-mica-kaolinite-illite, which is accurate and reliable.(2) Through the appraisal of various typical purple parent rocks mainly LSM in chongqing zone, the types of LSM are vermiculite, mica, kaolinite, illite, chlorite and so on. Through the K value method to calculate the different purple parent rocks in the different layer silicate minerals relative content of there are some differences, according to the geological, chronological order and LSM by the relative quantity of big to small order as:Triassic feixianguan dark purple mudstone LSM combination for chlorite, kaolinite, mica, illite, Jurassic group dark purple with mudstone artesian well mica, kaolinite, illite and vermiculite is given priority to, shaxi temple group ash brown purple mudstone for mica, illite, kaolinite and vermiculite combination, SuiNing group red brown purple mudstone is mica, illite, kaolinite, vermiculite, chlorite combination, penglai town group for mica, brown purple mudstone kaolinite, illite, chlorite combination, the cretaceous clip off group red purple mudstone for vermiculite, mica, illite, kaolinite. Furthermore, the purple parent rocks and form a purple soil LSM components were investigated, the results showed that the purple soil middle LSM composition and the corresponding purple parent rocks has a high consistency.(3) The change of relative content for LSM was studied, according to the order:rocks-stone bone soil-big earth-small earth, the content of different kinds of LSM had no obviously regularity, which indicated that purple soil in the development process, because the types of LSM is various, always keep the change, sustains the internal dynamic balance of change. But in the research of LSM, on the geological time with the total amount from old to new order, the amount of LSM was increase (beyond montmorillonite). Purple soil after weathering, accumulated, its chemical weathering decreased, which has a strong inheritance.(4) The change regulations of LSM have a correlation with original mineral potassium feldspar and albite. The correlations of the change regulations of potassium feldspar, illite and mica were very marked. The relative content of potassium feldspar increases with decreasing of illite and mica, vice versa. The regulation between kaolinite and albite was contrary. Vermiculite, chlorite and their mixture exist in soil, the content increases with deepeding of profile levels. The section distribution of LSM showed that, the relative content of vermiculite, chlorite and their mixture decreased with surface layer of soil profiles, while no regulation of profiles characterics of content with the difference of soils, kaolinite, chlorite and mica.(5) Compared the change of relative contents of potassium feldspar and albite with of LSM, the former content was abundant, the peak was single, which can be read as the frame silicate minerals in structure. They have goog atability, the source from purple rocks and soils is onefold, research clues is clear, which may be important in theoretical studies of mineralogy for purple soils. It should be added for further study.