摘要:
川南峨眉山大火成岩省中带与外带的交接部位,广泛分布与二叠纪峨眉山玄武岩风化有关的上二叠统龙潭组黏土岩,具有形成稀土等关键金属矿产资源的地质背景和成矿条件。对川南兴文地区长宁背斜上二叠统龙潭组下部的高岭石黏土岩进行了较为系统的地质调查,分析了黏土岩中的稀土元素含量。结果表明: 黏土岩的岩(矿)石类型包括高岭石黏土岩、含黄铁矿高岭石黏土岩以及碳质高岭石黏土岩,黏土岩样品中的ω(TRE2O3) 含量介于0.031%~0.409%(平均0.098%),矿化系数为0.61~8.19,矿化率达85%,具有较好的找矿潜力,含黄铁矿高岭石黏土岩中的稀土元素含量及矿化系数最高,是稀土富集的主要岩性组合; 样品为轻稀土富集型,具有中等的Eu负异常和弱Ce正异常; 地层接触关系与稀土元素特征指示龙潭组下部黏土岩的物源主要为峨眉山玄武岩和少量的中酸性岩。稀土元素的富集过程为峨眉山玄武岩风化首先形成初始富集,之后风化物质在海陆交互的氧化—还原环境下,稀土元素发生进一步迁移、吸附及沉淀,进而富集成矿。兴文地区龙潭组下部黏土岩中发现的稀土元素的富集,对于战略找矿行动具有一定的指导意义。
关键词:
-
稀土
/
-
龙潭组
/
-
富集过程
/
-
四川南部
Abstract:
Upper Permian Longtan Formation clay rocks, which are related to the weathering of Permian Emei basalt, are widely distributed in the middle zone and outer zone of Emei Large Igneous Province of Southern Sichuan, and they have geological background and metallogenic conditions for the formation of rare earth and other critical metal mineral resources. A systematic geological survey has been carried out in the lower part of Upper Permian kaolinitic clayston Longtan Formation in Changning anticline, and REE content in clay rocks was analyzed. The results show that the types of clay rocks (ore) include kaolinite clay rocks, pyrite bearing kaolinite clay rocks and carbonaceous kaolinite clay rocks. The content of ω(TRE2O3) in clay rock samples ranges from 0.031% to 0.409% (with average of 0.098%), and the mineralization coefficient is 0.61~8.19, with the mineralization rate up to 85%, indicating good prospecting potential. The REE content and mineralization coefficient are the highest in pyrite bearing kaolinite clay rocks, which are the main lithologic assemblages for REE enrichment. The samples are LREE enrichment type, with moderate negative Eu anomalies and weak positive Ce anomalies. The stratigraphic contact and rare earth elements characteristics indicate that the source materials are mainly from Emei basalts, and a small amount of medium-acid rocks in Emei Large Igneous Province. The enrichment process of rare earth elements includes the initial enrichment formed by Emei basalt weathering, and further migration, adsorption and precipitation of rare earth elements under the oxidation-reduction environment of sea and land interaction, and then the enrichment and mineralization. The discovery of the enrichment of rare earth elements in the clay rocks of the lower part of Longtan Formation in Xingan area has guiding significance for the strategic prospecting.
下载: