Geological, geochemistry and Sr, Nd, Pb isotopic characteristics of the Dazhuang Nb- REE deposit in southern margin of the North China craton

被引：0
|
作者：
Li Z. [1 ,2 ,3 ]
Li S. [4 ]
Zeng W. [2 ,3 ]
Li X. [2 ,3 ]
Pan X. [5 ]
Zhang S. [4 ]
Guo H. [2 ,3 ]
Liu W. [2 ,3 ]
机构：
[1] School of Earth Sciences and Resources, China University of Geosciences, Beijing
[2] Tianjin Center, China Geological Survey, Tianjin
[3] North China Center of Geoscience Innovation, Tianjin
[4] Henan Geological Survey Institute, Henan, Zhengzhou
[5] Henan Provincial Institute of Natural Resource Sciences, Henan, Zhengzhou
来源：
Dizhi Xuebao/Acta Geologica Sinica | 2023年 / 97卷 / 01期
关键词：
Dazhuang Nb-REE deposit; ore geology; petrogeochemistry; southern margin of the North China craton; Sr; Nd and Pb isotopes;
D O I：
10.19762/j.cnki.dizhixuebao.2022168
中图分类号：
学科分类号：
摘要：
Alkaline rock type Nb-REE deposit is an important type of Nb-REE mineral resources. The Dazhuang is a newly discovered medium-scale alkaline rock type Nb-REE deposit, which hosted in nepheline syenite on the southern margin of the North China craton, Fangcheng County, Henan Province. A total of 17 NW-SE trending Nb-REE orebodies with cystic, irregular and lenticular shapes are distributed in the Dazhuang deposit. The Nb-REE ores mainly occurs in hornblende nepheline syenite and biotite syenite. The ore minerals are mainly pyrochlore, bastnäsite-(Ce, La), fergusonite and niobium-rich titanite. The texture of ores mainly includes porphyritic structure, heteromorphic granular structure, semi-automorphic granular structure, inclusion structure, metasomatic structure, symbiotic structure, pegmatite structure, etc. Ore structure is divided into massive structure, vein structure, gneiss structure and so on. Hydrothermal alteration includes fluorite, sericitization, epidote and chlorite. Alkaline rock samples have the characteristics of low SiO2, rich alkali, and high aluminum. The total amount of rare earth elements is high, the light and heavy rare earths are fractionated obviously, and they have obvious negative δEu anomalies. They are enriched in high field strength elements such as Th, U, Zr, and Hf, obvious depleted in Ba, Sr, P and Ti. The Sr, Nd, and Pb isotopes of the whole alkaline rock are calculated as (87Sr/86Sr)i = 0.68158-0.71090, ϵNd(t)=-1.11-0.37, the two-stage model age (tDM2) is 1601-1540 Ma, (206Pb/204Pb)i=16.018-17.502, (207Pb/204Pb)i= 15.358-15.489, (208Pb/204Pb)i= 36.684-40.340. The geochemical characteristics show that the alkaline rock in the Fangcheng area belongs to the A1 subtype of the A-type rock suite. The magma evolution is mainly controlled by fractional crystallization. The original magma was derived from mantle where rich in phlogopite. Alkaline rocks in the Fangcheng area were formed under the tectonic setting of intraplate tension, which was a response to the breakup of the Rodinia supercontinent. On the whole, the main ore of the Dazhuang Nb-REE mineralization in the southern margin of the North China craton is controlled by magmatic crystal differentiation, Nb and REE were enriched in the late stage of magmatic crystallization, whereas the later hydrothermal activity has a certain enrichment effect on the Nb-REE mineralization. © 2023 Geological Society of China. All rights reserved.
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页码：82 / 108
页数：26
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