Geological And Geomorphological Characteristics And Formation Mechanism Of Granite In Mt. Sanqingshan, Jiangxi

Mt. Sanqingshan Geopark, Jiangxi, is the perfect combination for granite geology, geomorphology, ecology and humanities. Based on comprehensive collection and full summary of the results of previous studies, the inadequacies of the previous research, through all kinds of methods and means, such as field geological survey, microscope, hand specimen identification, main and trace element analysis, thermal low-temperature geochronology, Quaternary geology and geomorphology, this thesis has studied regional geological setting in Mt. Sanqingshan, geological features, petrography, characteristics of major and trace elements, mountain uplift and denudation mechanism, geomorphological features, landform zoning, micro-types of landscape, development mechanism of the landscapes, granite landform classification. The model of diagenetic�' mountain�'landscape in Mt. Sanqingshan has been established on the basis of domestic and abroad granite landscape comparison. The following are some understandings.1、The major geological events with important science sense and research value in Mt. Sanqingshan areas have been summarized, and geological heritages have been divided into five major categories.2、Through the major and trace element analysis of samples in different phases, the results show that silicon, aluminum and alkali content in Mt. Sanqingshan pluton is high, magnesium and iron is low. Generally they belong to high-K peraluminous calc-alkaline rock series. Analysis shows that Mt. Sanqingshan pluton is the product of crystallization differentiation of plagioclase, having experienced a higher evolution. A-type granite also indicates subduction has ended, entering an extensional environment of post-orogenic, and it is a response of left shear structure caused by northwest subduction of ancient Pacific Plate and thinning of Esat China lithospheric in Mesozoic period, which is consistent with the tectonic environment of Mt. Sanqingshan in Yanshan Movement and field geological phenomenon.3、Apatite fission track age in Mt Sanqingshan can be divided into three groups:70Ma,55 to 45Ma and 25Ma. The results of apatite fission-track analysis suggest that three age groups are related to the uplifting-erosion processes involved in forming ancient multilevel denudation planes at height 900m,1200m,1500m respectively. Thermal evolution history simulation can be generally divided into 4 stages-.90Ma to 65-60ma,65-60Ma to 45Ma, about 45Ma to 20-15Ma,20-15Ma till now. Uplift has obvious difference in different stages, and the uplift rate in Stage IV is significantly faster than the first three stages, reflecting the rapid uplift during the Neotectonic Movement. The average uplift amount is 3550m, the average erosion amount is 2540m, and the gap is 1010m, being very close to the height of Mt. Sanqingshan whose elevation is near 1000 meters. This is the process from magma emplacement at 6km underground to the mountainous landform today. Mt. Sanqingshan and Mt. Huangshan, Anhui have similar uplift and erosion characteristics, however, Mt. Sanqingshan has higher values in average cooling rate, average uplifting rate, average erosion rate than Mt. Huangshan, which is coherent to different landscape development stages in the two granite mountains. The results of fission track in Mt. Huangshan and Mt. Sanqingshan have constraints in landscape development characteristics in different stages and structure setting.4、Mt. Sanqingshan mainly includes ridges, peak wall, peak cluster, peak column, canyon, pictographic stone. Physiognomy type and main landscape unit areas in Mt. Sanqingshan have been divided.5、Mt. Sanqingshan granite landforms with the feature of spikes and steep slopes is the result of multi-factor coupling. The unique structure background is the rapid uplift geological setting, the material basis is A-type granite with high silicon, potassium-rich, low magnesium and calcium,the climatic condition is the typical subtropical monsoon climate zone and 4 major glacial events since the Quaternary, and landform development has been well preserved.6, Based on Erosion Cycles Theory by Davis, Mt. Sanqingshan landform is on the early stages of the juvenile and late stage of childhood according to the dominant landform signs. The model of diagenetic�' mountain�'landscape in Mt. Sanqingshan has been established.7、On the basis of worldwide comparison of granite landscapes, eight types, i. e. Mt. Sanqingshan style, Huangshan style, Huashan style, Taishan style.Gulangyu style, Keshenketeng style,Haisenchulu Style, Braunschweiger style, in different climatic zones,have been established.