Origin of the Ore-bearing Dolomite in Baiyun Obo Ore Deposit
-
摘要: 以白云鄂博矿区含矿白云岩的分布、野外地质产状等基础地质特征为基础，结合岩石学、矿物学和地球化学等一系列特征进行了研究，认为含矿白云岩既非典型的正常海相沉积碳酸盐岩，亦非典型的岩浆碳酸岩，它既有典型的海相沉积碳酸盐岩的某些特征，如其分布具有一定的时代性和层位性，呈层状、似层状或透镜状，与周围地层呈整合接触并与其同步褶皱和变形，具明显的层理等构造；同时又具有岩浆碳酸岩的某些特征，如沿深大断裂构造分布，下都有脉状体等。该白云岩还具有自己独特的特征，如具“眼式”构造，上都为层状，下部为脉状的“二元式”结构，它的C、O、Sr同位素特征介于海相碳酸盐和岩浆碳酸盐之间。上述特征都表明，白云岩为海底循环的热水流体喷溢沉积而成。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.
-
Key words:
- ore-bearing /
- hydrothermal exhalation /
- " /
- eye"
-
[1] 1 中国地质科学院地质研究所稀有金属组.内蒙及湖北某地稀有金属矿床、火山沉积稀有金属碳酸盐成因分析[J].地质矿产研究，1977,(1):27-49
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
7 Tu G Z,Zhao Z H, Qio Y Z. Evolution of Precambrian REE mineralization [J]. Precambrian Res.,1985, (27):131-135
8 中国科学院地球化学研究所.白云鄂博矿床地球化学[M].北京:科学出版社，1988
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
13 ODP Leg158 Shipboard scientific party. Active hydrothermal system drilled at the Mid-Atlantic Ridge[R]. 1995, 76(37):361-362
14 陈先沛，高计元，陈多福.热水沉积作用的概念和几个岩石学特点[J].沉积学报，1992,10(3):124-132
15 Peter m Herzig, Klaus P. I3ecker, Peter Stoffs,et al. Hydrothermal silica chimney fields in the Galapagos Spreading Center at 860W[J]. Earth and Planetry Science Letters, 1988, (89) : 261-272
16 Stoppa F, A R Woolley. The Italian carbonates; field occurrence,petrology and regional significance (l). Minerology and Petrology,1977,(59):43-67
17 张培善，陶克捷.白云鄂博矿物学〔M).北京:北京科学出版社，1986
18 Ross R Large. Australian volcanic-hosted massive sulfide deposits: features, styles, and generation models[J]. Econ. Geol.，1992,(87):471-510
19 Naomi Oreskes,Marco T Einaudi Origin of hydrothermal fluids at Olympic Dam: Preliminary results from fluid inclusion and stable isotopes[J].Economic Geology, 1992,(87):64-90
20 Zdzislaw Belka. Early Devonian Kess-Kess mud mounds of the eastern Anti-Atlas(Morocco)，and their relation to submarine hydrothermal venting[J]. Journal of Sedimentary Research, 1998,68(3):368-377
21 Shikazono N .Hydrthermal carbonates in altered wall rocks at the Uwamuki Kutoko deposits, Japan [J]. Mineralium Deposits,1998,(33):346-358
22 Hugh R Rollinson. Using stable isotope data:Evolution,Presentation, Interpretation [M]. Copublished in the United States with John Wiley&Sons, Inc.,New York, 1993
23 Bamann A. Lead and strontium isotopes in metalliferous and cal-careous pelitic sediments of the Red Sea axial troughCJ]. Mineralum Deposita,1994, (29) :81-93 -
点击查看大图
计量
- 文章访问数: 488
- HTML全文浏览量: 7
- PDF下载量: 387
- 被引次数: 0
下载:
