干旱区生态环境知识资源中心(Arid): Formation of banded chromitites and associated sulphides in the Neoproterozoic subarc deep-crustal magma inferred from the Alaskan-type complex, Egypt

Arid

DOI	10.1016/j.oregeorev.2020.103410
	Formation of banded chromitites and associated sulphides in the Neoproterozoic subarc deep-crustal magma inferred from the Alaskan-type complex, Egypt
	Khedr, Mohamed Zaki 1; Arai, Shoji 2; Morishita, Tomoaki 2
通讯作者	Khedr, Mohamed Zaki
来源期刊	ORE GEOLOGY REVIEWS
ISSN	0169-1368
EISSN	1872-7360
出版年	2020
卷号	120
英文摘要	The concentrically zoned Dahanib Alaskan-type complex in the Southern Eastern Desert (SED) of Egypt contains cumulate dunites associated with banded chromitites in the core, through harzburgites, wehrlites, and gabbroic rocks to the rim. Primary mineral inclusions hosted in chromian spinels of the banded chromitites are usually pargasite, orthopyroxene (Opx), aspidolite, phlogopite, edenite, olivine and PGE-bearing sulphides. The chromian spinel in Dahanib chromitites has a narrow range of Cr# (0.53-0.63) along with high Ti and Fe+3, like that in the host clinopyroxene-rich cumulate dunites. It resembles in chemistry to spinels in the Alaskan-type complex formed in an island arc setting. The early cumulus olivine in disseminated chromitites and host dunites (Fo(88-91)) shows a typical fractional crystallization trend. The interstitial clinopyroxene (Cpx) in chromitites is similar in chemical properties to Cpx crystallized from tholeiitic basalt melts, and traces a cumulate trend of arc-related Alaskan complexes. The peridotitic and gabbroic rocks contain primary amphiboles, which are pargasite and edenite with high Ti, Na and Al. The sulphide minerals are usually chalcopyrite, pentlandite and horomanite with subordinate Cu-pentlandite, cubanite, samaniite, heazlewoodite and pyrite. Pentlandite, horomanite and cubanite at temperatures between 900 and 1040 degrees C are rich in some platinum group elements (PGE: Os, Pt, Ir). They are classified into primary and secondary origins, which were crystallized from segregated sulphide droplets and from hydrothermal fluids at temperature < 760 degrees C during postmagmatic stage, respectively. The Dahanib banded chromitites and their mineral inclusions crystallized from hybrid melts, consisting of hydrous tholeiitic basalt melts mixed with slab-derived melts/fluids. They possibly formed by gravitational settling of semi-consolidated crystal mushes in a sub-arc lower-crustal magma chamber. Chemistry of primary minerals suggests that the Dahanib subarc deep-crustal magma is rich in Mg, Cr, Al, Ti, V, Ca, Sc and Na during the early magmatic stage, followed by increasing Fe, Mn, Ni, Co, Cu, S, Cs, B, Sr, and Pb with a progress of fractional crystallization.
英文关键词	Banded chromitites Sulphides Cumulate dunites Mineral inclusions Alaskan rocks Egypt
类型	Article
语种	英语
国家	Egypt ; Japan
收录类别	SCI-E
WOS记录号	WOS:000530673300031
WOS关键词	MAFIC-ULTRAMAFIC INTRUSION ; NI-PGE MINERALIZATION ; SOUTH EASTERN DESERT ; BUSHVELD COMPLEX ; ISLAND-ARC ; LAYERED INTRUSIONS ; MELT INCLUSIONS ; OMAN OPHIOLITE ; ORTHO-PYROXENE ; MERENSKY REEF
WOS类目	Geology ; Mineralogy ; Mining & Mineral Processing
WOS研究方向	Geology ; Mineralogy ; Mining & Mineral Processing
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/318616
作者单位	1.Kafrelsheikh Univ, Fac Sci, Dept Geol, Kafr Al Sheikh 33516, Egypt; 2.Kanazawa Univ, Dept Earth Sci, Kanazawa, Ishikawa 9201192, Japan
推荐引用方式 GB/T 7714	Khedr, Mohamed Zaki,Arai, Shoji,Morishita, Tomoaki. Formation of banded chromitites and associated sulphides in the Neoproterozoic subarc deep-crustal magma inferred from the Alaskan-type complex, Egypt[J],2020,120.
APA	Khedr, Mohamed Zaki,Arai, Shoji,&Morishita, Tomoaki.(2020).Formation of banded chromitites and associated sulphides in the Neoproterozoic subarc deep-crustal magma inferred from the Alaskan-type complex, Egypt.ORE GEOLOGY REVIEWS,120.
MLA	Khedr, Mohamed Zaki,et al."Formation of banded chromitites and associated sulphides in the Neoproterozoic subarc deep-crustal magma inferred from the Alaskan-type complex, Egypt".ORE GEOLOGY REVIEWS 120(2020).