Geochemical characteristics of illite clay rocks from the Shihezi Formation in the Hanxing mining area and its sedimentary environment  

作　　者：Xu Bohui Ding Shuli Wang Yu Liu Qinfu 

机构地区：[1]Key laboratory of Resource Survey and Research of Hebei Province, Hebei University of Engineering, Handan 056038, China [2]School of Geological Sciences, China University of Mining ＆ Technology, Beijing 100083, China

出　　处：《Mining Science and Technology》2011年第4期495-500,共6页矿业科学技术（英文版）

基　　金：supported by the National Nature Science Foundation of China (Nos. 41072031 and 40172119);the Natural Science Foundation of Hebei Province,China (No.D2009000833)

摘　　要：We studied the geochemical characteristics of illite clay rocks and their importance from the 5hihezi Formation of Late Permian in the Hanxing mining area by means of ICP-M5 and sequential X-ray fluorescence spectrometry. The results show that the amount of SiO2 is between 53.37% and 61.58% （by weight） and that of Al2O3 22.40% and 31.31% （by weight）. The ratio of SiO2/Al2O3 lies between 1.71 and 2.75. The amount of K2O ranges from 1.11% to 2.56% （by weight）. The amounts of Fe and Ti are higher than the theoretical values in illite clay rock would indicate. The amounts of some trace elements, such as Ga, As, Ba, Cu, Th and U are higher than their Clark values, while that of another 23 trace elements are found to be dose to their Clark values. The amounts of REE range from 22.59 to 570.54 μg/g, with an average of 163.23μg/g. The ratios of LREE/HREE range from 5.41 to 21.82, with an average of 8.87. These characteristics show that LREE are much richer in content than HREE. The REE distribution patterns of our samples were characterized by clearly negative Ce and Eu anomalies. We analyzed the sedimentary environment of the Hanxing mining area in Late Permian by the characteristic element ratio method. The ratios of Mn/Fe range from 0 to 0.0168, which are lower than those in a marine sedimentary environment. The ratios of Sr/Ba （0.20-0.41） are less than 1. These are all indications that the sediments of the Hanxing mining area in Late Permian form largely a continental sedimentary environment. The sedimentary water is freshwater, a conclusion reached on the basis of the ratios of Th/U （2.66-6.62） and of Ca/（Ca ＋ Fe） （0.01-0.059）; the average ratio of Fe2＋/Fe3＋ is 4.8. The sedimentary water condition is weakly acidic and weakly oxidative-weakly reductive, a conclusion reached on the basis of ratios of Fe2＋/Fe3＋ （4.8） and of Ceanom （-0.08）.We studied the geochemical characteristics of illite clay rocks and their importance from the Shihezi Formation of Late Permian in the Hanxing mining area by means of ICP-MS and sequential X-ray fluorescence spectrometry.The results show that the amount of SiO2 is between 53.37% and 61.58%(byweight) and that of Al2O3 22.40% and 31.31%(by weight).The ratio of SiO2/Al2O3 lies between 1.71and 2.75.The amount of K2O ranges from 1.11% to 2.56%(by weight).The amounts of Fe and Ti are higherthan the theoretical values in illite clay rock would indicate.The amounts of some trace elements,such asGa,As,Ba,Cu,Th and U are higher than their Clark values,while that of another 23 trace elements arefound to be close to their Clark values.The amounts of REE range from 22.59 to 570.54 lg/g,with an aver-age of 163.23 lg/g.The ratios of LREE/HREE range from 5.41 to 21.82,with an average of 8.87.These char-acteristics show that LREE are much richer in content than HREE.The REE distribution patterns of oursamples were characterized by clearly negative Ce and Eu anomalies.We analyzed the sedimentary environment of the Hanxing mining area in Late Permian by the characteristic element ratio method.Theratios of Mn/Fe range from 0 to 0.0168,which are lower than those in a marine sedimentary environment.The ratios of Sr/Ba(0.20-0.41) are less than 1.These are all indications that the sediments of the Hanxingmining area in Late Permian form largely a continental sedimentary environment.The sedimentary wateris freshwater,a conclusion reached on the basis of the ratios of Th/U(2.66-6.62) and of Ca/(Ca + Fe)(0.01-0.059);the average ratio of Fe2+/Fe3+ is 4.8.The sedimentary water condition is weakly acidicand weakly oxidative-weakly reductive,a conclusion reached on the basis of ratios of Fe2+/Fe3+(4.8)and of Ceanom(0.08).

关 键 词：Hanxing mining arealllite Trace elements Geochemical Sedimentary environment 

分 类 号：P618.51[天文地球—矿床学] P512.2[天文地球—地质学]