Formation age, geochemical signatures and geological significance of the Sanheming BIF-type iron deposit in the Guyang greenstone belt, Inner Mongolia

	Formation age, geochemical signatures and geological significance of the Sanheming BIF-type iron deposit in the Guyang greenstone belt, Inner Mongolia
	Liu Li 1,2; Zhang LianChang 1; Dai YanPei 1,2; Wang ChangLe 1,2; Li ZhiQuan 1,3
刊名	ACTA PETROLOGICA SINICA
	2012-11-01
卷号	28 期号:11 页码:3623-3637
关键词	Sanheming BIF-type iron deposit Zircon U-Pb age Geochemistry Guyang greenstone belt
ISSN号	1000-0569
文献子类	Article
英文摘要	The Sanheming BIF-type iron deposit occurs in the Guyang greenstone belt, which is located in the northern margin of Western Block of the North China Craton. The iron deposit is hosted in the Mount Se' erteng Group of Neoarchean Erathem with its ore bodies interlayered with amphibolites. The majority of the ores are characterized by granular crystalloblastic texture or granular-columnar crystalloblastic texture and banded or laminated structure. The ore consists predominantly of magnetite and quartz, secondary nonmetallic minerals include amphibole. SIMS U-Pb dating of zircons from the amphibolite interlayer shows that cores of the zircons characterized by core-rim texture and with a Th/U ratio of higher than 0.4 have an upper intercept age of 2562 +/- 14Ma, which is approximately the depositional age of the Sanheming BIF. Diagrams for protolith reconstruction reveal that the amphibolites are ortho-amphibolite and they are plotted within sub-alkaline basalt series and high-iron tholeiite in the Zr/Ti-Nb/Y diagram and Fe2O3T + TiO2-Al2O3 -MgO diagram, respectively. Major elements of the amphibolites are similar to those of MORB. Additionally, both REE profiles and spidergrams are flat in shape, roughly between those of N-MORB and E-MORB. LREE are slightly enriched with a (La/Yb)(N) ratio of 1.68, Th and U are relatively depleted, there are no apparent anomalies in terms of Nb, Ta, Zr and Hf, (La/Sm)(N) ratio and Nb/U ratio are 0.76 and 50, respectively. On the basis of such characteristics, it is deduced that protoliths of the amphibolites are T-MORB. Constraints from Ti-V and Th-Hf-Ta discrimination diagrams suggest the tectonic setting for the amphibolites are MORB or back-arc basin and N-MORB, respectively. Combining the general tectonic setting of T-MORB, i. e., mid-ocean ridge or back-arc basin, with the model of island arc-mantle plume interaction for the Guyang greenstone belt, it is speculated that the amphibolite interlayers were formed in a tectonic setting of back-arc basin, accomponied by mantle plume. The main chemical constituents of iron ore are SiO2, Fe2O3 and FeO. Extremely low content of Al2O3 (0.68%), TiO2 (0.04%) and HFSE indicates that the involvement of continental detritus is minor. Chondrite-normalized REE profiles for the iron ores and those of the komatiites occurring at the bottom of Guyang greenstone belt are alike. PAAS-normalized REY profiles resemble that of the mixture of high-temperature hydrothermal fluid and seawater, the typical characteristics of which include the depletion of LREE, enrichment of HREE ((La/Yb)(SN) = 0.34), strongly positive europium anomaly (delta Eu = 2.33), slightly positive yttrium anomaly (delta Y = 1.13), a Y/Ho weight ratio of 29 and mole ratio of 53. Based on the similar signatures to komatiite and the mixture of high-temperature hydrothermal fluid and seawater, it is inferred that Fe and Si of the Sanheming BIF-type iron deposit were supplied through the high-temperature hydrothermal leaching of komatiites.
WOS关键词	RARE-EARTH-ELEMENTS ; NORTH CHINA CRATON ; TRACE-ELEMENT ; OCEANIC-CRUST ; SOUTH-AFRICA ; SEAWATER ; YTTRIUM ; BASALTS ; FRACTIONATION ; PACIFIC
WOS研究方向	Geology
语种	英语
出版者	SCIENCE PRESS
WOS记录号	WOS:000312572600014
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/84284]
专题	中国科学院地质与地球物理研究所
通讯作者	Liu Li
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 3.China Univ Geosci, Beijing 100083, Peoples R China
推荐引用方式 GB/T 7714	Liu Li,Zhang LianChang,Dai YanPei,et al. Formation age, geochemical signatures and geological significance of the Sanheming BIF-type iron deposit in the Guyang greenstone belt, Inner Mongolia[J]. ACTA PETROLOGICA SINICA,2012,28(11):3623-3637.
APA	Liu Li,Zhang LianChang,Dai YanPei,Wang ChangLe,&Li ZhiQuan.(2012).Formation age, geochemical signatures and geological significance of the Sanheming BIF-type iron deposit in the Guyang greenstone belt, Inner Mongolia.ACTA PETROLOGICA SINICA,28(11),3623-3637.
MLA	Liu Li,et al."Formation age, geochemical signatures and geological significance of the Sanheming BIF-type iron deposit in the Guyang greenstone belt, Inner Mongolia".ACTA PETROLOGICA SINICA 28.11(2012):3623-3637.