The role of uranyl complex decomposition and redox conditions in the precipitation of hydrothermal uranium deposits: Insights from chlorite mineralogy and geochemistry in the Shazhou uranium deposit, Xiangshan, SE China

绿泥石 铀矿 地质学 黑云母 地球化学 热液循环 铀矿石 铀酰 白云母 黄铁矿 矿物 矿物学 化学 材料科学 石英 古生物学 有机化学 地震学 冶金
作者
Ji-Qiang Cui,Shui‐Yuan Yang,Shao‐Yong Jiang,Hao Wang,Ruoxi Zhang,Xiang-Sheng Tang,Yongjie Yan
出处
期刊:Geological Society of America Bulletin [Geological Society of America]
被引量:2
标识
DOI:10.1130/b36737.1
摘要

Uranium precipitation involves the decomposition of uranyl complexes and the reduction of hexavalent uranium, which can occur sequentially or simultaneously within one redox reaction. The redox condition of hydrothermal fluid plays a vital role in controlling the migration and precipitation of uranium in hydrothermal uranium deposits. However, little attention has been paid to the role of uranyl complex decomposition in uranium precipitation. In this study, chlorite mineralogy and geochemistry were examined to clarify the process of uranium precipitation in the Shazhou deposit, Xiangshan uranium orefield, Southeast China. Based on comprehensive petrographic and mineral chemistry studies of chlorites obtained from altered granite porphyries and uranium ores, five types of chlorites were identified: (1) chlorite present in the form of pseudomorphous biotite, which was produced by the hydrothermal alteration of biotite in rocks that underwent hematitization and chloritization (Chl-I); (2) chlorite filling the cleavage cracks in biotite in rocks that underwent hematitization and chloritization (Chl-II); (3) chlorite occurring in pyrite veins (Chl-III); (4) chlorite intergrown with pitchblende in ore veins (Chl-IV); and (5) chlorite occurring in calcite veins (Chl-V). Chlorite geothermometry revealed that the formation temperatures of the five types of chlorites ranged from 219 °C to 254 °C. Mineral chemistry analyses revealed that the five types of chlorites formed in a reductive fluid environment, where the oxygen fugacity at different stages is similar, with log fO2 values ranging from −41.6 to −39.1. Uranium precipitation started only in stage Chl-IV. The examination of the mineral assemblage revealed that the ore-forming fluid was rich in F−, HPO32−, and CO32−. Comprehensive investigation of chemistry and physicochemical conditions of the ore-forming fluid revealed that oxidized uranium (UO22+) could be complexed with HPO42− and F−, and uranyl phosphate and the uranyl fluoride complexes were the main uranium species when uranium precipitation and the decomposition occurred at stage Chl-IV. However, the assessment of oxygen fugacity of the solution equilibria between the UO2(s) and the uranyl phosphate and uranyl fluoride complexes revealed that the reducibility of the fluid favoring the reduction of uranyl ions (UO22+) to U4+ was insufficient to reduce the uranyl phosphate and uranyl fluoride complexes. This indicates that the breakup of uranyl phosphate and the uranyl fluoride complexes to release uranyl ions should occur first at stage Chl-IV, reducing uranyl ions to U4+, and leading to uranium precipitation. Hence, the decomposition of uranyl complexes played an important role in uranium precipitation. With the increase in pH, uranyl phosphate and the uranyl fluoride complexes gradually decomposed and became reducible. Moreover, the decrease in ligand concentration was conducive to the decomposition of uranyl phosphate and the uranyl fluoride complexes. During the formation of the Shazhou deposit, the fluid boiling process induced the loss of volatiles, such as CO2, CH4, HF, and H2S, leading to an increase in pH and decrease in HPO42−, F−, and CO32− concentrations in the fluid. These factors also led to the decomposition of uranyl fluoride and the uranyl phosphate complexes and the precipitation of fluorapatite and calcite. Uranium was then reduced by the action of Fe2+ and S− (pyrite) from a hexavalent to a tetravalent, and finally, uranium was precipitated to form uranium ores.
最长约 10秒,即可获得该文献文件

科研通智能强力驱动
Strongly Powered by AbleSci AI
更新
PDF的下载单位、IP信息已删除 (2025-6-4)

科研通是完全免费的文献互助平台,具备全网最快的应助速度,最高的求助完成率。 对每一个文献求助,科研通都将尽心尽力,给求助人一个满意的交代。
实时播报
1秒前
好多好多鱼完成签到 ,获得积分10
1秒前
量子星尘发布了新的文献求助10
2秒前
YM发布了新的文献求助10
2秒前
3秒前
3秒前
YU发布了新的文献求助10
3秒前
3秒前
种草发布了新的文献求助10
3秒前
Lucas应助端庄的雁易采纳,获得10
4秒前
樱桃完成签到 ,获得积分10
4秒前
4秒前
5秒前
慕青应助soulking采纳,获得10
5秒前
6秒前
sluck完成签到,获得积分10
6秒前
ymlllym完成签到,获得积分10
6秒前
iiiau发布了新的文献求助10
7秒前
游鱼完成签到,获得积分10
7秒前
7秒前
xuxuxuxuxu完成签到,获得积分10
7秒前
ku_zhang完成签到 ,获得积分10
7秒前
8秒前
写个锤子完成签到,获得积分10
8秒前
9秒前
南宫初兰发布了新的文献求助10
9秒前
littlebenk发布了新的文献求助10
10秒前
ddd发布了新的文献求助10
10秒前
e746700020发布了新的文献求助10
11秒前
FashionBoy应助顺心的书包采纳,获得10
12秒前
Jasper应助YU采纳,获得10
12秒前
超级炎彬应助weijie采纳,获得20
12秒前
13秒前
十七发布了新的文献求助10
13秒前
wzh1745完成签到,获得积分10
14秒前
一步一个脚印完成签到,获得积分10
14秒前
14秒前
14秒前
心灵美的山蝶完成签到,获得积分10
14秒前
哈利波波1021完成签到,获得积分10
15秒前
高分求助中
A new approach to the extrapolation of accelerated life test data 1000
Cognitive Neuroscience: The Biology of the Mind 1000
Technical Brochure TB 814: LPIT applications in HV gas insulated switchgear 1000
ACSM’s Guidelines for Exercise Testing and Prescription, 12th edition 500
Picture Books with Same-sex Parented Families: Unintentional Censorship 500
Nucleophilic substitution in azasydnone-modified dinitroanisoles 500
不知道标题是什么 500
热门求助领域 (近24小时)
化学 材料科学 医学 生物 工程类 有机化学 生物化学 物理 内科学 纳米技术 计算机科学 化学工程 复合材料 遗传学 基因 物理化学 催化作用 冶金 细胞生物学 免疫学
热门帖子
关注 科研通微信公众号,转发送积分 3970172
求助须知:如何正确求助?哪些是违规求助? 3514982
关于积分的说明 11176568
捐赠科研通 3250212
什么是DOI,文献DOI怎么找? 1795198
邀请新用户注册赠送积分活动 875702
科研通“疑难数据库(出版商)”最低求助积分说明 805004