干旱区生态环境知识资源中心(Arid): Proterozoic ophiolite and chromite

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DOI	10.18654/1000-0569/2019.10.03
	Proterozoic ophiolite and chromite
	Bao PeiSheng
通讯作者	Bao, PS (corresponding author), Chinese Acad Geol Sci, Inst Geol, MNR Key Lab Deep Earth Dynam, Beijing 100037, Peoples R China.
来源期刊	ACTA PETROLOGICA SINICA
ISSN	1000-0569
EISSN	2095-8927
出版年	2019
卷号	35 期号:10 页码:2971-2988
英文摘要	Based on a large number of publications, this paper summarized the outcrops and characteristics of the Proterozoic ophiolites outside China, as well as the similarities and differences between the Proterozoic and Phanerozoic ophiolites. Also, it introduced the development and genesis of chromite deposits in the Proterozoic ophiolites in the world, mainly to clarify whether the chromite deposits were formed by magma differentiation or by partial melting of mantle peridotite. The existing data show that ophiolites occurred either in Early Proterozoic or in Middle-Late Proterozoic. The Early Proterozoic ophiolites are rare, and are represented by the Prutuniq ophiolite (2. 05 similar to 2. 0Ga) in the Cape Smith belt of the Canadian Shield and the Outokumpu and Jormua ophiolites (1. 97 similar to 1. 96Ga) in the Fennoscandian shield (Finland). The Middle-Late Proterozoic ophiolites crop out in many places, such as the desert of the east of Egypt (similar to 750Ma) and the northeast of Africa (ca. 900 similar to 800Ma). Several typical characters of the Proterozoic ophiolites are as following: (1) The ophiolites are all dismembered. They are generally associated with arc-type volcanic rocks and/or melanges, and have undergone different degrees of deformation and metamorphism (greenschist to amphibolite facies); (2) They mostly have relatively complete rock assemblage of oceanic crust, including mafic-ultramafic cumulate, gabbro, sheeted dike complex, and volcanic rock. The rhythmic layering of the mafic-ultramafic rocks and compositional variations in minerals indicate multistage magmatic activities in an open magma chamber; (3) Either high-Al or high-Cr chromite deposits may occur in the Proterozoic ophiolites, mainly in the dunite unit. The compositions of the chromites are controlled by the degree of partial melting and the activity of hydrous fluids in different evolution stages of supra-subduction zone (SSZ). The chromites usually have low TiO2 contents. The chromite deposits formed by magma differentiation and are generally small in scale, different from the Phenerozoic podiform chromites which represent partial melting residue within the mantle; (4) The Proterozoic ophiolites are often associated with sulfide Cu-Co-Zn-Au ore deposit (e.g., the Outokumpu ophiolite). The chromites usually have high Zn (0. 11% similar to 0. 18%) (e. g., the Outokumpu ophiolite) and high MnO (up to 1. 79%) (e. g., the Wizer ophiolite in the Central Eastern Desert in Egypt); (5) The Proterozoic ophiolites mostly formed in SSZ settings (e. g., those from Egypt, Northeast Africa, and Outokumpu in Finland), and a few formed in mid-ocean spreading ridge (e. g., the Purtuniq ophiolite in Canada) and rifts (e. g., the Jomua ophiolite in Finland).
英文关键词	Proterozoic Ophiolite Chromite Tectonic setting
类型	Article
语种	中文
收录类别	SCI-E
WOS记录号	WOS:000491168800003
WOS关键词	CAPE-SMITH BELT ; CENTRAL EASTERN DESERT ; NORTHERN OMAN OPHIOLITE ; U-PB GEOCHRONOLOGY ; MAFIC-ULTRAMAFIC COMPLEX ; GA JORMUA OPHIOLITE ; RED-SEA HILLS ; PETROLOGICAL CHARACTERISTICS ; SUPRA-SUBDUCTION ; MANTLE SECTION
WOS类目	Geology
WOS研究方向	Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/369689
作者单位	[Bao PeiSheng] Chinese Acad Geol Sci, Inst Geol, MNR Key Lab Deep Earth Dynam, Beijing 100037, Peoples R China
推荐引用方式 GB/T 7714	Bao PeiSheng. Proterozoic ophiolite and chromite[J],2019,35(10):2971-2988.
APA	Bao PeiSheng.(2019).Proterozoic ophiolite and chromite.ACTA PETROLOGICA SINICA,35(10),2971-2988.
MLA	Bao PeiSheng."Proterozoic ophiolite and chromite".ACTA PETROLOGICA SINICA 35.10(2019):2971-2988.

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