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Two episodic Nb-Ta mineralization events and genesis of the Zhaojinggou rare-metal deposit, north margin of the North China Craton
被引:17
|作者:
Zhang, Lu
[1
]
Jiang, Shao-Yong
[1
,2
]
机构:
[1] China Univ Geosci, Sch Earth Resources, State Key Lab Geol Proc & Mineral Resources, Wuhan 430074, Peoples R China
[2] China Univ Geosci, Minist Educ, Key Lab Geol Survey & Evaluat, Wuhan 430074, Peoples R China
基金:
国家重点研发计划;
关键词:
Nb-Ta mineralization;
A-type granite;
Episodic magmatism;
Zhaojinggou deposit;
Central north margin NCC;
A-TYPE GRANITES;
U-PB GEOCHRONOLOGY;
CHEMICAL EVOLUTION;
INNER-MONGOLIA;
TEXTURAL FEATURES;
TRACE-ELEMENTS;
SOUTH CHINA;
CONSTRAINTS;
PETROGENESIS;
FRACTIONATION;
D O I:
10.1016/j.oregeorev.2021.103994
中图分类号:
P5 [地质学];
学科分类号:
0709 ;
081803 ;
摘要:
The Zhaojinggou rare-metal deposit is located in the Wulashan-Daqingshan region, central north margin of the North China Craton. Nb-Ta mineralizations are mainly hosted in the biotite alkali-feldspar granite (BAG) and albite granite (AG), with subordinate mineralization in the alkali-feldspar aplite dyke (AFA), the amazonite granitic pegmatite dyke (AGP), and the greisen (black + white colored greisen). In this paper, we present a systematic work of geochronology (CGM U-Pb combined with cassiterite U-Pb, monazite U-Th-Pb, and muscovite 40Ar-39Ar dating), whole-rock geochemistry, and Sr-Nd isotopes to understanding the timing of mineralization, petrogenesis, geodynamic setting, and ore-forming processes. Our geochronological data reveal two episodic NbTa mineralization events in the Zhaojinggou deposit during the Early Cretaceous. The first and major ore-forming episode occurred at -130 Ma, forming a sequence of ore-bearing rocks of the BAG-AG-greisen-AFA. The second but subordinate ore-forming episode occurred at -114 Ma, forming the ore-bearing AGP. The whole-rock geochemistry indicates the granitic rocks (the BAG-AG-AFA and AGP) from the two episodes are highly evolved with analogous trace element and REE patterns, and have A-type affinity. The whole-rock ?Nd(t) values of these granitic rocks are relative similar, ranging from -9.6 to -7.6, with corresponding T2DM ages of 1490?1713 Ma. These features suggest that these A-type granites from the two discrete episodes are derived from the same magma reservoir by high-temperature partial melting of the Middle Proterozoic basement in an infracrustal extensional environment. These A-type granites experienced extremely fractional crystallization during emplacement. The whole-rock REE tetrad effects, element ratios (Nb/Ta, Zr/Hf and K/Rb), and Nb-Ta fractionation modeling indicate that both magmatic and hydrothermal processes are involved to form the two episodic Nb-Ta mineralizations. High degree of factional crystallization and magmatic-hydrothermal processes after high-temperature anataxis are crucial to form the Zhaojinggou rare-metal deposit. Moreover, these highlyevolved A-type granites (the BAG-AG-AFA and AGP) formed during the Early Cretaceous (at - 130 Ma and 114 Ma respectively) are the important targets for rare-metals prospecting in the central north margin of the
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页数:18
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