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471.
被动源激发极化法的野外试验结果 总被引:10,自引:0,他引:10
对被动源激发极化法场源的基本性质、激发极化效应的提取方法进行了讨论,以野外试验结果为例研究了矿体与异常的对应规律,对该方法的有效性和可行性进行了说明。 相似文献
472.
Quartz was studied with respect to its silicon isotopic composition and cathodoluminescence in micro-fine disseminated gold deposits in SW Guizhou and NW Guangxi.The results showed that quartz in wall rocks.ores and that in association with hydrothermal silicification are distinctive in silicon isotopes and cathodoluminescence characters.Quartz in association with primary silicification is non-luminescent while that in wall rocks and associated with secondary silicification exhibits striking luminescence.Based on the dynamic fractionation of silicon isotopes,it is suggested that the mineralization was accompanied by rapid transport of aprimary siliceous fluid along the major deep fault system into subordinate faults before ore components deposited in favorable strata via penetration and metasomatism.Therefore,a deep origin is implicit for gold deposits of this type. 相似文献
473.
StudyonfinestructureofcrustmantletransitionzoneinYanqingHailaibasinbasedonCDPandDSSdataJINCHENG1)(成瑾)QINGHELI2)(李清河)1)In... 相似文献
474.
Processes of the deposition and vicissitude of Mu Us Desert, China since 150 ka B.P. 总被引:1,自引:0,他引:1
Li Baosheng Jin Heling Lü Haiyan Zhu Yizhi Dong Guangrong Sun Donghuai Zhang Jiashen Gao Quanzhou Yan Mancun 《中国科学D辑(英文版)》1998,41(3):248-254
“Milanggouwan stratigraphical section” named lately takes down 27 cycles of alternately evolutionary histories of desert depositions
in the Mu Us area with the fluviolacustrine facies and palaeosols since 150 ka B. P. Studies show that the sedimentary form
was induced by the growth and decline and confrontation each other between the winter monsoon and the summer monsoon of East
Asia in the past 150 ka.
Project supported by the National Natural Science Foundation of China (Grant No. 49473192). 相似文献
475.
从信息论及贝叶斯模型出发,以长期异常背景为基础,近期异常为依据,在对未来十年R度的地震趋势进行估计的条件下,预测了河北北部2005年前强震危险性,给出了区域内强震发生和各裂度概率的空间分布。 相似文献
476.
477.
通过对比中国长白山区和朝鲜白头山区新生代火山岩系的层序和同位素年代学资料,首次编制出中朝边境地区新生代火山岩系分布图和新生代火山喷发阶段对比表。其岩石化学和地球化学演化趋势表明,该区新生代火山完全有可能再次喷发。 相似文献
478.
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480.
Jin‐Jing Lee Cheng‐Shin Jang Sheng‐Wei Wang Chin‐Ping Liang Chen‐Wuing Liu 《水文研究》2008,22(16):3029-3041
This study characterized the redox conditions in arsenic‐affected groundwater aquifers of the Lanyang plain, Taiwan. Discriminant analysis was adopted to delineate three redox zones (oxidative, transitional and reductive zones) in different aquifers and yielded 92·3% correctness on groundwater quality data. Arsenic is mainly distributed in the reductive zone, and arsenic distribution in the shallow aquifer is mainly affected by surface activities. According to PHREEQC modelling results, possible mechanisms for arsenic release to groundwater in Lanyang plain are explored. Arsenic released to groundwater in the oxidative zone (zone 1) is primarily caused by the oxidations of arsenic‐bearing pyrite minerals, and arsenate is the predominant species. While the reductive dissolution of Fe‐oxides are responsible for the high arsenic concentration found in the transitional and reductive zones (zones 2 and 3), arsenite is the predominant species. The reduction potential of groundwater rises as the depths and zones increase. Some sulphates may be reduced to form sulphide ions, which then react with arsenic to form arseno‐sulphide deposits (such as realgar, orpiment) and then slightly lower groundwater arsenic concentrations. A conceptual diagram which summarized the possible release processes of arsenic in different redox zones along groundwater flow in Lanyang plain is postulated. Arsenic‐bearing pyrite and arsenopyrite (FeAsS) are oxidized as they are exposed to the infiltrated oxygenated rainwater, releasing soluble arsenate Fe(II) and SO42? into zone 1. The dissolution of arsenic‐rich Fe‐oxides due to the onset of reducing conditions in zones 2 and 3 is responsible for the mobility of arsenic and likely to be the primary mechanism of arsenic release to groundwater in the Lanyang plain Copyright © 2007 John Wiley & Sons, Ltd. 相似文献