干旱区生态环境知识资源中心(Arid): Paleomagnetism of a late Neoproterozoic mafic-ultramafic layered intrusion of Gebel Dahanib, South Eastern Desert (Egypt): Implications for magma evolution and timing of magnetization acquisition

Arid

DOI	10.1016/j.jafrearsci.2020.104016
	Paleomagnetism of a late Neoproterozoic mafic-ultramafic layered intrusion of Gebel Dahanib, South Eastern Desert (Egypt): Implications for magma evolution and timing of magnetization acquisition
	Abu El-Ela, Fawzy Farahat; Mahgoub, Ahmed Nasser; Ibrahim, Hamza Ahmed; El-Hemaly, Ibrahim Ali; Manuel Alva-Valdivia, Luis; Bohnel, Harald
通讯作者	Mahgoub, AN (corresponding author), Univ Nacl Autonoma Mexico, Inst Geofis, Ciudad De Mexico 04510, Mexico.
来源期刊	JOURNAL OF AFRICAN EARTH SCIENCES
ISSN	1464-343X
EISSN	1879-1956
出版年	2020
卷号	172
英文摘要	We present detailed rock magnetic and paleomagnetic results for a late Neoprotemzoic mafic-ultramafic layered intrusion of Gebel Dahanib, South Eastern Desert, Egypt. Gebel Dahanib intrusion (GDI) is an elliptical body with saucer or funnel shape, and was intruded into deformed country rocks at similar to 710 Ma. It consists of two main undeformed and unmetamorphosed sequences: I) a lower ultramafic sequence composed mainly of peridotite (dunite and lherzolite cumulate) and pymxenite (olivine websterite and websterite cumulates). Dunite cumulate occupies the basal part, which grades upward to lherzolite and pymxenite cumulates at the top of the ultramafic sequence; and II) an upper mafic sequence that comprises olivine gabbronorite, gabbmnorite, norite, and a chilled margin of fine-grained gabbronorite. An intrusive contact was observed between ultramafic and mafic sequences, which suggests an asynchronous emplacement history. To understand the magmatic evolution of GDI and to make a new contribution to the small African Neoprotemzoic paleomagnetic database, 260 oriented samples were collected from four rock units (peridotite, pyroxenite, gabbro, and fine-grained gabbro). Rock magnetic experiments combined with Fe-Ti microscopic observations and demagnetization procedures indicate that both sequences have different magnetic mineral contents and paleomagnetic components. A stable component with northwesterly declination and shallow negative inclination carried by magnetite and pyrrhotite was isolated from the ultramafic sequence (Dec = 326.6 degrees, Inc = -28.2 degrees, alpha(95) = 5.5 degrees, and k = 58.72), and the corresponding paleomagnetic pole lies at lat = 39.0 degrees N, long = 261.5 degrees E, A(95) = 4.6 degrees, and K = 83.13. Paleomagnetic analyses on the mafic sequence yielded northeast-directed declinations, with intermediate positive inclinations (Dec = 11.3 degrees, Inc = 47.6 degrees, alpha(95) = 3.9 degrees, and k = 103.19), and a paleomagnetic pole lat = 78.7 degrees N, long = 96.2 degrees E, A(95) = 4.4 degrees, and K = 81.49. We postulate that the Dahanib intrusion was emplaced in two pulses: the first includes the ultramafic assemblages at the base of the intrusion; the second magma pulse makes up the upper mafic sequence. Assessment of Egyptian paleomagnetic poles from a similar time period (similar to 710-540 Ma) indicates that only one pole (out of 21) can be considered reliable, and also from the African dataset only five of 43 poles are of high quality. These indicate that new high-quality paleomagnetic poles are needed to refine the late Neoproterozoic paleomagnetic database for Egypt and the African continent.
英文关键词	Gebel Dahanib Egypt late Neoproterozoic Rock magnetism Paleomagnetism Africa
类型	Article
语种	英语
收录类别	SCI-E
WOS记录号	WOS:000590387100049
WOS类目	Geosciences, Multidisciplinary
WOS研究方向	Geology
来源机构	Universidad Nacional Autónoma de México
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/348958
作者单位	[Abu El-Ela, Fawzy Farahat; Mahgoub, Ahmed Nasser; Ibrahim, Hamza Ahmed] Assiut Univ, Geol Dept, Assiut 71516, Egypt; [Mahgoub, Ahmed Nasser; Manuel Alva-Valdivia, Luis] Univ Nacl Autonoma Mexico, Inst Geofis, Lab Paleomagnetismo, Ciudad De Mexico 04510, Mexico; [El-Hemaly, Ibrahim Ali] Natl Res Inst Astron & Geophys, Helwan, Egypt; [Bohnel, Harald] Univ Nacl Autonoma Mexico, Ctr Geociencias, Blvd Juriquilla 3001, Queretaro 76230, Mexico
推荐引用方式 GB/T 7714	Abu El-Ela, Fawzy Farahat,Mahgoub, Ahmed Nasser,Ibrahim, Hamza Ahmed,et al. Paleomagnetism of a late Neoproterozoic mafic-ultramafic layered intrusion of Gebel Dahanib, South Eastern Desert (Egypt): Implications for magma evolution and timing of magnetization acquisition[J]. Universidad Nacional Autónoma de México,2020,172.
APA	Abu El-Ela, Fawzy Farahat,Mahgoub, Ahmed Nasser,Ibrahim, Hamza Ahmed,El-Hemaly, Ibrahim Ali,Manuel Alva-Valdivia, Luis,&Bohnel, Harald.(2020).Paleomagnetism of a late Neoproterozoic mafic-ultramafic layered intrusion of Gebel Dahanib, South Eastern Desert (Egypt): Implications for magma evolution and timing of magnetization acquisition.JOURNAL OF AFRICAN EARTH SCIENCES,172.
MLA	Abu El-Ela, Fawzy Farahat,et al."Paleomagnetism of a late Neoproterozoic mafic-ultramafic layered intrusion of Gebel Dahanib, South Eastern Desert (Egypt): Implications for magma evolution and timing of magnetization acquisition".JOURNAL OF AFRICAN EARTH SCIENCES 172(2020).