Characters and Metallogenetic Significance of Organic Matter in Coal from the Daying Sandstone-Hosted Uranium Deposit in the Northern Ordos Basin, China
Author:
Li Qi12ORCID, Wu Bailin1, Luo Jingjing1, Yang Songlin3, Wang Miao12, Liu Mingyi1, Lin Zhouyang1, Zhang Xiaorui1, Zhang Long4, Wang Jiangqiang1, Yang Mengdi1
Affiliation:
1. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, China 2. Research Institute of Exploration and Development, PetroChina Changqing Oilfield Company, Xi’an 710021, China 3. Research Institute of Exploration and Development, PetroChina Liaohe Oilfield Company, Panjin 124010, China 4. College of Earth Science and Engineering, Xi’an Shiyou University, Xi’an 710065, China
Abstract
Coal is usually found in many sandstone-hosted uranium deposits in western China. However, it remains unclear whether coal organic matter is related to the mineralization of uranium in sandstone. In this study, the organic matter of coal containing lenticular carbon plant strips and carbon clastics was analyzed in different alteration zones in the Daying sandstone-hosted uranium deposit located in the northern Ordos Basin. According to geological and geochemical characters, Daying sandstone can be classified into three alteration zones: the oxidation zone, the transition zone, and the reduction zone. The results are as follows. Firstly, the maceral organic matter of the coal at Daying is mostly vitrinite, indicating the characters of humic coal. The maturity of the organic matter is low, which is in the transitional evolution stage of immature lignite or lignite-long-flame coal. Secondly, the kerogen is mainly type III (humic type), which can be easily transformed into humic acid with a strong adsorption capacity for uranium. Thirdly, the vitrinite reflectance (Ro) of the coal organic matter in the transition zone is higher than that of the other alteration zones. Meanwhile, there are bright white bands in the microscopic components of the organic matter of the coal in the transition zone (mineralized zone) and a certain composition of the sapropelite has strong fluorescence. All three aforementioned phenomena are related to the radioactivity of uranium, and each of them possesses the potential for application in mineral exploration. Fourthly, the extraction and separation of humic substances indicates that humic acid plays a key role in organic matter-related uranium mineralization. In the transition zone, uranium can co-precipitate as a humate, and the transition zone’s organic carbon content increases. Therefore, the organic matter in coal contributes to sandstone-hosted uranium mineralization, providing a further guide to prospecting methodologies.
Funder
Natural Science Basic Research Program (Key) Project of Shaanxi Province, China China Geological Survey Project Science and Technology Project of PetroChina Liaohe Oilfield Company Uranium Resource Potential and Techno-Economic Evaluation Project in Central Kyzyl-Kum Region, Uzbekistan, Key R&D Program of Shaanxi Province, China
Subject
Geology,Geotechnical Engineering and Engineering Geology
Reference48 articles.
1. Space-Time Coordinate of the Evolution and Reformation and Mineralization Response in Ordos Basin;Liu;Acta Geol. Sin.,2006 2. Discussion on the classification about the uranium deposit;Jin;Geol. Surv. Res.,2014 3. The roles of organic matter in the formation of uranium deposit in sedimentary rock;Charles;Ore Geol. Rev.,1996 4. Binding of uranyl by humic acid;Shanbhag;Nucl. Chem.,1981 5. The role of humic substances in the transport and fixation of metals of economic interest (Au, Pt, U, V);Wood;Ore Geol. Rev.,1996
|
|