| 四川冕宁木落寨稀土矿床稀土矿化与围岩特征 |
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| 关键词:Muluozhai REE deposit marble green schist bastnaesite ore type |
| 基金项目:国家自然科学基金(编号: 41772044);中国地质科学院基本科研业务费项目(编号: YYWF201509; YYWF201704);中国地质调查局地质调查项目(编号: 1212011020000150011-03) |
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| REE Mineralization and Characteristics of Wall Rocks in the Muluozhai REE Deposit, Mianning County, Sichuan Province |
| The Muluozhai deposit is a main REE deposit in the Mianning–Dechang REE belt, which is located in the north of the belt and the west of Yalong River fault. The formation of this REE deposit was closely related to the carbonate-syenite complexes. Unlike other REE deposits in the Mianning–Dechang REE belt, such as the Maoniuping deposit and the Dalucao deposit, whose main wall rocks are quartz diorite, the wall rocks in the Muluozhai deposit are more complex, and the main types are marble, green schist, alkali granite and some other rocks. It has been shown that quartz diorite was not the main REE source of Maoniuping and Dalucao deposit, and the effect of these wall rocks on mineralization of the Muluozhai deposit needs further studies. ICP-MS and XRF were used to analyze the major and trace elements of the main wall rocks—marble and green schist, the REE patterns of these wall rocks exhibit a declined LREE (3×10–6 ~20×10–6 for marble, 62×10–6 ~ 74×10–6 for green schist), flat HREE, low total REE content (4×10–6~21×10–6 for marble, 86×10–6~97×10–6 for green schist). Compared with the REE content (592×10–6~2 026×10–6) of syenite of Muluozhai and total REE in carbonate-syenite complexes of other three deposits in the Mianning–Dechang metallogenic belt (carbonate 2 470×10–6~40 807×10–6, syenite 630×10–6~3 233×10–6) studied in the past, the REE values of marble and green schist are too low, as shown in the source of REE materials, and hence these two types of wall rocks might not have contributed much to ore formation. According to the profile display, most of the orebodies appear in the syenite fractures, with a few occurring in the contact surface between syenite and marble, and marble probably provided CO2– 3 and promoted metasomatism and mineralization. The orebodies of the Muluozhai deposit are mainly of veinlet dissemination type, followed by stripe type. Hand specimens as well as microscopic and BSE image observations show that gangue minerals are mainly fluorite + calcite + barite + gypsum + pyrite + galena + quartz + phlogopite, and ore mineral is bastnaesite. Bastnaesite overlies these gangue minerals, indicating that the deposit was mainly formed at the latest stage of the hydrothermal period. |
| OUYANG Huai,LIU Yan.2018.REE Mineralization and Characteristics of Wall Rocks in the Muluozhai REE Deposit, Mianning County, Sichuan Province[J].Acta Geoscientica Sinica,39(3):329-341. |
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