XUE Hong-fu1, HUANG Wei-hu1*, ZENG Dao-guo1, JIN Zhong-guo2, HUANG Zhi-long3, WU Lin3, XIANG Zhen-zhong3, YE Lin3
(1. Institute of Geology and Mineral Exploration, Non-ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou, Guiyang 550005, China;
2. Non-ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou, Guiyang 550005, China;
3. Stake Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China)
Abstract: The rare earth elements (REE) ore-bearing layer (Pxt) in the Yulong area of in the Northwest Guizhou is distributed at the bottom of Xuanwei Formation (P3x), and overlaid disconformably above the Emeishan basalt Formation (P2-3em). It is composed of aluminous and ferruginous claystones, with its thicknesses ranging from 3.25m to 18.76 m under restriction of the low-lying undulation on the unconformity surface of the basement. The REE ore-bearing layer can be subdivided to 7 seams, with the Ⅱ and Ⅳ seams as the main ore seams, which are characterized with continuous distribution, large thickness and high grade. The existence of aluminous segment is a direct factor affecting the production of the high-grade REE ore, The REE mineralization and enrichment are selective to lithology. Aluminous claystone, carbonaceous aluminous mudstone, compact aluminous mudstone and clastic/oolitic aluminous mudstone are of dominant lithofacies for the REE enrichment. These REE-enriched samples have Nb2O5 contents of 130×10-6-550×10-6, ZrO2 contents of 0.06%-0.38%, and TFe contents of 7.94%-24.72%, with A/S ratios of 0.82-3.60. The aluminous segment is the concentrated distribution area with REO grades of ≥0.18% for its various samples. The aluminous segments in the south side of the central part of the east limb and the north side of the central part of the west limb of the Hujiaying syncline are continuously distributed with large thickness. They are key targeting segments for the further REE ore-prospecting in the area. Especially, the southern part of the east limb of the Hujiaying syncline should be firstly choosed for the further REE exploration target as there is very thick aluminous segment containing complete combination of advantageous rock facies.
Keywords: the REE mineralization ; Ore-controlling factors; ore-prospecting direction; the northwestern Guizhou
