Knowledge Resource Center for Ecological Environment in Arid Area
DOI | 10.1016/j.jafrearsci.2017.10.007 |
Garnierite-bearing serpentinite from the Central Eastern Desert of Egypt: A signature of paleo-weathering in the Arabian Nubian Shield? | |
Hamdy, Mohamed M.1; El Dien, Hamed Gamal1,2; Abd El-Wahed, Mohamed A.1; Morishita, Tomoaki2 | |
通讯作者 | Hamdy, Mohamed M. |
来源期刊 | JOURNAL OF AFRICAN EARTH SCIENCES
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ISSN | 1464-343X |
EISSN | 1879-1956 |
出版年 | 2018 |
卷号 | 146页码:95-117 |
英文摘要 | This paper records the garnierite in Wadi Dubur Neoproterozoic serpentinites from the Central Eastern Desert of Egypt. Garnierite (Ni-Mg hydrous silicates) occurs in two types (Type 1 and Type II) of infillings in the weathered serpentinite that was displaced sinisterly by NNW-SSE trending strike-slip faulting and dextrally with NE-trending shearing. All recognized garnierites are serpentine-like (nepouite/pecoraite) existing in mixtures with the hosting serpentines. The Type I garnierite is Fe-richer [Mg0.25-0.71 Ni1.22-1.79 Fe1.28-3.05 Al (0.0-0.02) Sil(1.11-L73) O-5(OH)(4)] showing zoning in a collomorph texture, while the Type II garnierite is homogenous with more Si and Mg [Mg0.54-0.94 Ni1.38-2.04 Fe0.38-1.20 Al (0.0-0.01) Si1.66-2.10 O-5(OH)(4)]. Raman spectra indicate that the substitution of Ni for Fe formed a poorly crystalline goethite. The serpentinization of the Dubur peridotite protolith and the associated alteration of chromite and Ni-sulfides were important for the early individualization of Ni. It is proposed that the unweathered serpentinites represent the bedrock, while the altered garnierite-bearing ones represent the saprock. The early weathering of serpentinites contemporaneous with a faulting activation caused in situ precipitation of Ni and Fe in veins (Type 1 garnierite). With the faulting repetition and progressive alteration maintenance Ni, Si and Mg were transferred to the percolating meteoric solutions, and moved downward through the weathering profile precipitating the Type II garnierite in gouges. Although the studied Ni-rich rocks represent a narrow mineralogical occurrence, they are remnants of a former lateritic regolith most probably formed by tropical or sub-tropical weathering during Cretaceous at the expense of Wadi Dubur Neoproterozoic serpentinites. The formed regolith has been subsequently largely eroded, buried and recently exhumed in arid climate. (C) 2017 Elsevier Ltd. All rights reserved. |
英文关键词 | Garnierite Wadi Dubur faulted Neoproterozoic serpentinite Mineralogy Whole-rock chemistry Phanerozoic Ni-lateritization Central Eastern Desert |
类型 | Article |
语种 | 英语 |
国家 | Egypt ; Japan |
收录类别 | SCI-E |
WOS记录号 | WOS:000447568000008 |
WOS关键词 | NEW-CALEDONIA ; ULTRAMAFIC ROCKS ; NI-LATERITE ; RAMAN-SPECTROSCOPY ; WESTERN-AUSTRALIA ; ORE-DEPOSITS ; NICKEL ; MINERALOGY ; SILICATE ; GEOCHEMISTRY |
WOS类目 | Geosciences, Multidisciplinary |
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/2XILL650/210404 |
作者单位 | 1.Tanta Univ, Geol Dept, Fac Sci, Tanta 31527, Egypt; 2.Kanazawa Univ, Sch Nat Syst, Dept Earth Sci, Kanazawa, Ishikawa 9201192, Japan |
推荐引用方式 GB/T 7714 | Hamdy, Mohamed M.,El Dien, Hamed Gamal,Abd El-Wahed, Mohamed A.,et al. Garnierite-bearing serpentinite from the Central Eastern Desert of Egypt: A signature of paleo-weathering in the Arabian Nubian Shield?[J],2018,146:95-117. |
APA | Hamdy, Mohamed M.,El Dien, Hamed Gamal,Abd El-Wahed, Mohamed A.,&Morishita, Tomoaki.(2018).Garnierite-bearing serpentinite from the Central Eastern Desert of Egypt: A signature of paleo-weathering in the Arabian Nubian Shield?.JOURNAL OF AFRICAN EARTH SCIENCES,146,95-117. |
MLA | Hamdy, Mohamed M.,et al."Garnierite-bearing serpentinite from the Central Eastern Desert of Egypt: A signature of paleo-weathering in the Arabian Nubian Shield?".JOURNAL OF AFRICAN EARTH SCIENCES 146(2018):95-117. |
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