Econ. Environ. Geol. 2013; 46(2): 179-198

Published online April 30, 2013

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

The Geochemistry and Zircon Trace Element Characteristics of A-type Granitoids in Boziguoer, Baicheng County, Xinjiang

Yin Jingwu1*, Liu Chunhua2, Park Jung Hyun1, Shao Xingkun3, Yang Haitao4, Xu Haiming5 and Wang Jun5

1Chinese University of Geosciences, Beijing 100083, China
2State Key Laboratory for Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
3Detachment of General Gold Party, Chinese People’s Armed Police Force, Mudanjiang 157021, Heilongjiang, China
4North-west institute of nonferrous metals geology, Xi an 710054, China
5Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China

Correspondence to :

Yin Jingwu

yinjw@cugb.edu.cn

Received: April 8, 2013; Accepted: April 19, 2013

Abstract

The Boziguoer A-type granitoids in Baicheng County, Xinjiang, belong to the northern margin of the Tarim platform as well as the neighboring EW-oriented alkaline intrusive rocks. Those rocks comprise an aegirine or arfvedsonite quartz alkali feldspar syenite, an aegirine or arfvedsonite alkali feldspar granite, and a biotite alkali feldspar syenite. The major rock-forming minerals are albite, K-feldspar, quartz, arfvedsonite, aegirine, and siderophyllite. The accessory minerals are mainly zircon, pyrochlore, thorite, fluorite, monazite, bastnaesite, xenotime, and astrophyllite. The chemical composition of the alkaline(A-type) granitoids show that SiO2 varies from 64.55wt.% to 72.29wt.% with a mean value of 67.32wt.%, Na2O + K2O is high(9.85 ~ 11.87wt.%) with a mean of 11.14wt.%, K2O is 2.39 ~ 5.47wt.%(mean = 4.73wt.%), the K2O/Na2O ratios are 0.31 ~ 0.96, Al2O3 ranges from 12.58wt.% to 15.44wt.%, and total FeO is between 2.35wt.% and 5.65wt.%. CaO, MgO, MnO and TiO2 are low. The REE content is high and the total ΣREE is 263 ~ 1,219 ppm(mean = 776 ppm), showing LREE enrichment HREE depletion with strong negative Eu anomalies. In addition, the chondritenormalized
REE patterns of the alkaline(A-type) granitoids belong to the ‘‘seagull’’ pattern of the right-type. The Zr content is 113 ~ 1,246 ppm(mean = 594 ppm), Zr + Nb + Ce + Y is between 478 ~ 2,203 ppm with a mean of 1,362 ppm. Furthermore, the alkaline(A-type) granitoids have high HFSE(Ga, Nb, Ta, Zr and Hf) content and low LILE(Ba, K and Sr) content. The Nb/Ta ratio varies from 7.23 to 32.59(mean = 16.59) and the Zr/Hf ratio is 16.69 ~ 58.04(mean = 36.80). The zircons are depleted in LREE and enriched in HREE. The chondrite-normalized REE patterns of the zircons are of the ‘‘seagull’’ pattern of the left-inclined type with strong negative Eu anomaly and without a Ce anomaly. The Boziguoer A-type granitoids share similar features with A1-type granites. Liu et al.(2012) suggested that the average temperature of the granitic magma was estimated at 832 ~ 839oC. Therefore, the Boziguoer A-type granitoids show crust-mantle mixing
and may have formed in an anorogenic intraplate tectonic setting under high-temperature, anhydrous, and low oxygen fugacity conditions.

Keywords Southwest Tianshan, Boziguoer A-type granitoids, REE, HREE, LREE, geochemistry

Article

Econ. Environ. Geol. 2013; 46(2): 179-198

Published online April 30, 2013

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

The Geochemistry and Zircon Trace Element Characteristics of A-type Granitoids in Boziguoer, Baicheng County, Xinjiang

Yin Jingwu1*, Liu Chunhua2, Park Jung Hyun1, Shao Xingkun3, Yang Haitao4, Xu Haiming5 and Wang Jun5

1Chinese University of Geosciences, Beijing 100083, China
2State Key Laboratory for Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
3Detachment of General Gold Party, Chinese People’s Armed Police Force, Mudanjiang 157021, Heilongjiang, China
4North-west institute of nonferrous metals geology, Xi an 710054, China
5Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China

Correspondence to:

Yin Jingwu

yinjw@cugb.edu.cn

Received: April 8, 2013; Accepted: April 19, 2013

Abstract

The Boziguoer A-type granitoids in Baicheng County, Xinjiang, belong to the northern margin of the Tarim platform as well as the neighboring EW-oriented alkaline intrusive rocks. Those rocks comprise an aegirine or arfvedsonite quartz alkali feldspar syenite, an aegirine or arfvedsonite alkali feldspar granite, and a biotite alkali feldspar syenite. The major rock-forming minerals are albite, K-feldspar, quartz, arfvedsonite, aegirine, and siderophyllite. The accessory minerals are mainly zircon, pyrochlore, thorite, fluorite, monazite, bastnaesite, xenotime, and astrophyllite. The chemical composition of the alkaline(A-type) granitoids show that SiO2 varies from 64.55wt.% to 72.29wt.% with a mean value of 67.32wt.%, Na2O + K2O is high(9.85 ~ 11.87wt.%) with a mean of 11.14wt.%, K2O is 2.39 ~ 5.47wt.%(mean = 4.73wt.%), the K2O/Na2O ratios are 0.31 ~ 0.96, Al2O3 ranges from 12.58wt.% to 15.44wt.%, and total FeO is between 2.35wt.% and 5.65wt.%. CaO, MgO, MnO and TiO2 are low. The REE content is high and the total ΣREE is 263 ~ 1,219 ppm(mean = 776 ppm), showing LREE enrichment HREE depletion with strong negative Eu anomalies. In addition, the chondritenormalized
REE patterns of the alkaline(A-type) granitoids belong to the ‘‘seagull’’ pattern of the right-type. The Zr content is 113 ~ 1,246 ppm(mean = 594 ppm), Zr + Nb + Ce + Y is between 478 ~ 2,203 ppm with a mean of 1,362 ppm. Furthermore, the alkaline(A-type) granitoids have high HFSE(Ga, Nb, Ta, Zr and Hf) content and low LILE(Ba, K and Sr) content. The Nb/Ta ratio varies from 7.23 to 32.59(mean = 16.59) and the Zr/Hf ratio is 16.69 ~ 58.04(mean = 36.80). The zircons are depleted in LREE and enriched in HREE. The chondrite-normalized REE patterns of the zircons are of the ‘‘seagull’’ pattern of the left-inclined type with strong negative Eu anomaly and without a Ce anomaly. The Boziguoer A-type granitoids share similar features with A1-type granites. Liu et al.(2012) suggested that the average temperature of the granitic magma was estimated at 832 ~ 839oC. Therefore, the Boziguoer A-type granitoids show crust-mantle mixing
and may have formed in an anorogenic intraplate tectonic setting under high-temperature, anhydrous, and low oxygen fugacity conditions.

Keywords Southwest Tianshan, Boziguoer A-type granitoids, REE, HREE, LREE, geochemistry

    KSEEG
    Jun 30, 2024 Vol.57 No.3, pp. 281~352

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