| Pinghe district of Zhangzhou city in Fujian province is a typical area of the Wuyishan vegetation coverage area where has a typical subtropical humid monsoon climate. Fu’an-Nanjing NE deep fault and Shanghang-Yuxiao NW deep fault have crossed the area, where developed number of NE-trending NW-trending structures. Jiangle-Hua’an, Taining-Longyan two SN-trending structures and Xiamen-Nanjing EW-trending faults zone directly affect the study area so as to form a very complex geological structure, topography and controlled by tectonic activity. Vegetation is abundant in the study area where located in Shanghang-Yunxiao polymetallic and alunite ore belt, which has been preliminarily discovered as copper, molybdenum, iron, lead, zinc, gold, etc. and pyrophyllite, kaolin, peat of other minerals. It has excellent ore-forming conditions and prospecting potential. However, it makes geological field work in difficult conditions becauce of exuberant vegetation development, Quaternary covered extensively and undulating terrain. This vegetation area is very suitable for mineral prospecting using remote sensing technology which is an efficient and low cost method. This study uses the theories of remote sensing, botany, botanogeochemistry and petrology to systematically investigate the natural landscapes, spectral characteristics of the typical ground objects, RS image features and characteristics of vegetation community in copper-molybbenum mining area. It finds out the distribution features of main mineralization elements and theirs accompanying elements in rock, soil and vegetation in different ore deposits and quantitative analyses the relationship between the known deposits and the linear structure extracted from RS image in the study area. The outcomes can reveal the effective indicative vegetation (elements) in different ore deposits. This paper analyzes the spectral feature of various plants, find out the spectral anomalies of dominant plant species in the study area. A correlation model has been established by the inheritance anomaly showing in ore-forming parent rock, soil, vegetation and hyperspectral image, and then discussed the characteristics of spatial distribution of remote sensing botanogeochemistry in copper molybdenum deposit of high vegetation covered area. It provided a good application value and reference for prediction of metal deposits in vegetation coverage area. The research comes to the results:(1) In order to quantify the lineament structures, the box-counting fractal model has been used as statistical methods to describe the characteristics of fractal for lineations in study area. Based on the statistical results, the fractal dimensions of the spatial distribution of the linear structures in four selected hydrothermal-type ore deposits of Pinghe district, named Zhongteng, Panchi, Dafanshan and Xiaofanshan, are 1.43,1.52,1.37 and 1.37, respectively, which are higher than the values in South China. It also indicated that these lineaments are statistically self-similar. There is an annular region with high indices in the 10-step tendency map that is coincident with the Zhongteng circular structure in the ETM+image, which corresponds to the largest caldera in the study area. Combining the above quantitative analysis results with the geological data, it can be used as an important reference for the prediction of favorable metallogenic area.(2)The results of spectral analysis of typical vegetation in the hydrothermal-type copper-molybbenum mining area and the periphery of the mining area show that they are consistent in the form of waveform characteristics, red edge characteristics, chlorophyll, water absorption, vegetation index and other aspects of the performance. It can be seen that the heavy metal elements are enriched in the leaf body and affect the normal growth of vegetation which leading to the periphery of the mining and mining area vegetation characteristic waveform differences from the characteristic of vegetation of Imperata cylindrica, Dicranopteris dichotoma, Blechnum orientale, Citrus maxima and other vegetation. The reflectance of leaf’s surface is lower than that of normal area. The wave is moved 5-25nm to blue or red band. The characteristics of chlorophyll and water absorption were different, and there were significant differences in vegetation index. The wave anomaly for leaf of Citrus maxima and Dicranopteris dichotoma are more obvious. Therefore, Citrus maxima and Dicranopteris dichotoma can be used as effective indicative vegetation.(3)The main mineralization elements and their accompanying elements in rock, soil and vegetation in the mining area are higher than background area. The high value of contrast coefficient indicated that there is certain consanguinity and material inheritance between rock、soil and vegetation. That is to say, the geochemical characteristics of rock, soil and vegetation, could reflect the formation of botanogeochemical anomaly.(4) The accumulation ability of ore-forming elements in different types of vegetation and different organs of same plants are different. The enrichment ability of ore-forming elements in leafs by the most common vegetation species are stronger than that of stems. For example, W, Mo, Co, Bi and Cu elements are rich in the leaves of Citrus maxima, but Zn and Pb elements are rich in the stems. All elements are rich in the leaves of Dicranopteris dichotoma, and there is no element ebnrichment in the stems.(5) Two indexes, shielding coefficient and contrast coefficient of elements, have been used as two parameters to chose and evaluate mine prospecting effective indicative vegetation combined with the results of spectral analysis for common vegetation in mining area.The selection of the effective indicative vegetation (elements) in this study as shown below:Citrus maxima and Dicranopteris dichotoma (Pb、Mo、Co、Bi) can be chose as mine prospecting effective indicative vegetation and elements in copper-molybbenum mining area.(6) A multiple regression equation was establish by water absorption depth of vegetation spectral and effective indicative elements using vegetation geochemical anomaly data combined with field spectral data and hyperspectral image data in Panchi copper molybdenum mine area. It can be quantitative inverse the spatial distribution characteristics of the indicative elements combined with multi spectral images for analysis of hydrothermal deposits and other relevant materials. It is demonstrated that the method can reflects the area of relevant elements in the abnormal spatial distribution characteristics based on remote sensing vegetation spectral anomalies of vegetation coverage area of copper and molybdenum mineralization information and has a good effect for prospecting application. |
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