Redistribution of REE in granitic bedrocks during incipient weathering: insights into the role of groundwater in the formation of regolith-hosted REE deposit
文献类型：期刊论文
| 作者 | Dou, Jingzhao3; Wang, Christina Yan1,2,3; Xing, Yanlu5; Tan, Wei1,2,3; Zhao, Zisong3,4 |
| 刊名 | CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
 |
| 出版日期 | 2023-10-01 |
| 卷号 | 178期号:10页码:19 |
| 关键词 | Titanite Fractionation and enrichment of REE Groundwater-rock interaction Regolith-hosted REE deposit South China |
| ISSN号 | 0010-7999 |
| DOI | 10.1007/s00410-023-02054-4 |
| 英文摘要 | The regolith-hosted rare earth element (REE) deposits in the Nanling Mountain Range, South China, are the most important source of heavy REE (HREE) in the world. A perplexing thing is that only a few of these deposits are relatively enriched in HREE and most of them are actually light REE (LREE)-enriched, although they are all originated from the granitic bedrocks with similar HREE concentrations. This is supposed to be related to the redistribution of REE in the weathered bedrocks due to groundwater-rock interaction, however, it remains enigmatic how REEs are mobilized and fractionated in the interaction. Titanite is an important REE contributor to the regolith-hosted REE deposit. Here, we investigate textural and compositional variations of the titanite from the granitic bedrocks to weathered profiles in the Zuokeng regolith-hosted REE deposit, the largest one that is newly discovered in this region. Together with thermodynamic modelling, we deduce the nature of the fluids, temperature range for titanite alteration, and the mechanism of REE fractionation. Primary titanite is of magmatic in origin and shows relatively high REE contents and negative Eu anomaly on the chondrite-normalized REE pattern. Secondary titanite is commonly associated with chloritized biotite and is characterized by extremely low REE, high Al2O3, F and significant positive Eu anomaly, typical of authigenic origin due to chloritization of biotite under oxidized conditions in supergene environment. From the bedrocks upward to the surface, primary titanite is gradually replaced by calcite, synchysite-(Ce) and TiO2 in the weathered bedrocks. This is interpreted as the result of infiltration of the F, carbonate-rich, alkaline fluids derived from local groundwater through the bedrocks. The irregular dark patches in primary titanite display typical alteration texture and may have formed through fluid leaching of primary titanite. The patches in primary titanite have lower REE concentrations and higher LREE/HREE ratios than magmatic domains, indicating that the groundwater preferentially scavenges HREE from primary titanite, leaving behind LREE in weatherable secondary minerals, such as synchysite-(Ce) and allanite. Mass balance calculation results also confirm that more HREE are lost from weathered bedrocks than LREE. Therefore, the interaction of groundwater and granitic bedrocks may be favorable to enrich LREE rather than HREE in the regolith. This may explain why most regolith-hosted REE deposits like Zuokeng in South China are of predominant in LREE. This study highlights the role of groundwater in mobilizing, fractionating and enriching REE from the granitic bedrocks to resultant regolith-hosted REE deposits. |
| WOS研究方向 | Geochemistry & Geophysics ; Mineralogy |
| 语种 | 英语 |
| WOS记录号 | WOS:001070230300002 |
| 源URL | [http://ir.gig.ac.cn/handle/344008/74884]  |
| 专题 | 中国科学院矿物学与成矿学重点实验室 |
| 通讯作者 | Wang, Christina Yan |
| 作者单位 | 1.Guangdong Prov Key Lab Mineral Phys & Mat, Guangzhou 510640, Peoples R China 2.CAS Ctr Excellence Deep Earth Sci, Guangzhou 510640, Peoples R China 3.Chinese Acad Sci, Guangzhou Inst Geochem, CAS Key Lab Mineral & Metallogeny, Guangzhou 510640, Peoples R China 4.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 5.Monash Univ, Sch Earth Atmosphere & Environm, Clayton, Vic 3800, Australia |
| 推荐引用方式 GB/T 7714 | Dou, Jingzhao,Wang, Christina Yan,Xing, Yanlu,et al. Redistribution of REE in granitic bedrocks during incipient weathering: insights into the role of groundwater in the formation of regolith-hosted REE deposit[J]. CONTRIBUTIONS TO MINERALOGY AND PETROLOGY,2023,178(10):19. |
| APA | Dou, Jingzhao,Wang, Christina Yan,Xing, Yanlu,Tan, Wei,&Zhao, Zisong.(2023).Redistribution of REE in granitic bedrocks during incipient weathering: insights into the role of groundwater in the formation of regolith-hosted REE deposit.CONTRIBUTIONS TO MINERALOGY AND PETROLOGY,178(10),19. |
| MLA | Dou, Jingzhao,et al."Redistribution of REE in granitic bedrocks during incipient weathering: insights into the role of groundwater in the formation of regolith-hosted REE deposit".CONTRIBUTIONS TO MINERALOGY AND PETROLOGY 178.10(2023):19. |
入库方式： OAI收割
来源：广州地球化学研究所
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