Origin of the Ore-bearing Dolomite in Baiyun Obo Ore Deposit

GAO Ji-yuan; WANG Yi-xian; QIU Yu-zhuo; ZHANG Qian

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Article Navigation > Acta Sedimentologica Sinica > 1999 > 17(S1): 675-680

GAO Ji-yuan, WANG Yi-xian, QIU Yu-zhuo, ZHANG Qian. Origin of the Ore-bearing Dolomite in Baiyun Obo Ore Deposit[J]. Acta Sedimentologica Sinica, 1999, 17(S1): 675-680.

Citation:

GAO Ji-yuan, WANG Yi-xian, QIU Yu-zhuo, ZHANG Qian. Origin of the Ore-bearing Dolomite in Baiyun Obo Ore Deposit[J]. Acta Sedimentologica Sinica, 1999, 17(S1): 675-680.

Origin of the Ore-bearing Dolomite in Baiyun Obo Ore Deposit

1.
Guangzhou Institute of Geochemistry,Chinese Academy of Sciences Guangzhou 510640;
2.
Institute of Geochemistry, Chinese Academy of Sciences Guiyang 550002

Received Date: 1999-01-08
Rev Recd Date: 1999-05-18
Publish Date: 1999-12-10

Abstract

The superlarge Fe-Nb-REE ore deposit at Baiyun Obo is one of the most large Nb-REE ore deposits in the world,which is hosted by dolomite in the Baiyun Obo Formation of Middle Prpterozoic age. In this paper the tectonic setting,regional geology,regional distribution,occurrence,petrology, mineralogy and C-,O-,Sr-isotopic geochemistry of the ore-bearing dolomite in Baiyun Obo, Inner Mongolia,China are studied. The ore-bearing dolomite is only located in the Baiyun Obo Formation of Middle Proterozoic age. It shows some features of normal marine sedimentary carbonate, such as special time-stratigraphic distribution,stratiform and lens shaped, laminated and bedded structures, conformable contact and synchronous fold with wall rocks; and some features of magmatic carbonatite,such as distribution along deep fault,thin dolomite vein cutting wall rocks in heading wall, so the dolomite is neither the normal marine sedimentary carbonate northe magmatic carbonatite. The dolomite distributed along regional fault in stratiform,stratifold and lentiform was controlled by second tectonic basin. The dolomite thickness in center is much larger, and the thickness in marginal is much smaller or thin out. The dolomite displays special "eye-type" structure,e. g massive strucure in the center part, banded and laminated in the margin. The dolomite shows "two-end structures",e. g. stratiform body is located in upper part and vein in lower part,in which the stratigraphic position of the vein dolomite is not overstep the stratigraphic position of the stratiform dolomite. The ore-bearing dolomite have 8180 per mil values between +6.4 and +16.5,andδ¹³Cvalues between-4.7 and +1.4,which is located between the normal marine sedimentary and magmatic car- bonates. ⁸⁷Sr/⁸⁶Sr data have confirmed this conclution. To sum up,authors believes that the dolomite was formed by hydrothermal venting which was circulating in submarine.
- ore-bearing,
- hydrothermal exhalation,
- ",
- eye"

References

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2 刘铁庚.白云鄂博白云岩氧、碳同位素组成及其成因讨论[J].地质论评,1986,32(2):150-159

3 白鸽，袁忠信，吴澄宇等.白云鄂博矿床地质特征和成因论征[CM].北京:地质出版社，1996

4 Le Bas M J, Spiro B,Yang Xueming. Oxygen, Carbon and Stron-tium isotope study of -the carbonitic dolomite host of the Bayun Obo Fe-Nb-REE deposit, Inner Mongolia, N. China [J]. Miner-alogical Magazine, 1997 (61) ; 531-541

5 孟庆润.论白云鄂博铁矿含矿围岩一白雄壮岩的沉积成因及沉积环境分析[J].地质论评,1982,28(5):481-488

6 王中刚，李邵柄，苏贤泽.沉积变质热液交代型稀土铁矿床的成因特征[J].地球化学，1973,(1):5-11

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9 章雨旭，彭阳，乔秀夫等.白云鄂博矿床赋矿白云岩成因新认识[J].地质论评，1998,44(1);70

10 孟庆润，Drew L J.内蒙古白云鄂博“H。含矿白云岩”氧、碳同位素研究及其成因[J].地质找矿论丛,1992,7(2):46-52

11 王揖，李双庆，王保良等.狼山白云鄂博裂谷系[M].中国北方构造丛书.北京:北京大学出版社，1992

12 李士勤.再论内蒙古白云鄂博含稀有金属碳酸盐及铌一稀土一铁矿床成因〔A].中国北方板块构造文集，第一集[C].北京:地质出版社，1983. 156-185

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沈阳化工大学材料科学与工程学院沈阳 110142

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Origin of the Ore-bearing Dolomite in Baiyun Obo Ore Deposit

1. Guangzhou Institute of Geochemistry,Chinese Academy of Sciences Guangzhou 510640;

2. Institute of Geochemistry, Chinese Academy of Sciences Guiyang 550002

Received Date: 1999-01-08

Rev Recd Date: 1999-05-18

Publish Date: 1999-12-10

Key words:

ore-bearing /
hydrothermal exhalation /
" /
eye"

Abstract: The superlarge Fe-Nb-REE ore deposit at Baiyun Obo is one of the most large Nb-REE ore deposits in the world,which is hosted by dolomite in the Baiyun Obo Formation of Middle Prpterozoic age. In this paper the tectonic setting,regional geology,regional distribution,occurrence,petrology, mineralogy and C-,O-,Sr-isotopic geochemistry of the ore-bearing dolomite in Baiyun Obo, Inner Mongolia,China are studied. The ore-bearing dolomite is only located in the Baiyun Obo Formation of Middle Proterozoic age. It shows some features of normal marine sedimentary carbonate, such as special time-stratigraphic distribution,stratiform and lens shaped, laminated and bedded structures, conformable contact and synchronous fold with wall rocks; and some features of magmatic carbonatite,such as distribution along deep fault,thin dolomite vein cutting wall rocks in heading wall, so the dolomite is neither the normal marine sedimentary carbonate northe magmatic carbonatite. The dolomite distributed along regional fault in stratiform,stratifold and lentiform was controlled by second tectonic basin. The dolomite thickness in center is much larger, and the thickness in marginal is much smaller or thin out. The dolomite displays special "eye-type" structure,e. g massive strucure in the center part, banded and laminated in the margin. The dolomite shows "two-end structures",e. g. stratiform body is located in upper part and vein in lower part,in which the stratigraphic position of the vein dolomite is not overstep the stratigraphic position of the stratiform dolomite. The ore-bearing dolomite have 8180 per mil values between +6.4 and +16.5,andδ¹³Cvalues between-4.7 and +1.4,which is located between the normal marine sedimentary and magmatic car- bonates. ⁸⁷Sr/⁸⁶Sr data have confirmed this conclution. To sum up,authors believes that the dolomite was formed by hydrothermal venting which was circulating in submarine.

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Origin of the Ore-bearing Dolomite in Baiyun Obo Ore Deposit

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