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| The chromite deposits associated with ophiolite complexes, Southeastern Desert, Egypt: Petrological and geochemical characteristics and mineralization | |
| Saleh, Gehad M. | |
| 通讯作者 | Saleh, GM |
| 来源期刊 | ACTA GEOCHIMICA
 |
| ISSN | 2096-0956 |
| EISSN | 2365-7499 |
| 出版年 | 2006 |
| 卷号 | 25期号:4页码:307-317 |
| 英文摘要 | The podiform chromitites occur in a well-preserved mantle sequence consisting of lherzolite-harzburgite with abundant lenses of olivine dunite. The podiform chromitite deposits are common as small and irregularly shaped masses in the Southeastern Desert (SED) of Egypt. The podiform chromitites exhibit a wide range of compositions from high Cr to high Al varieties. The Cr of chrome spinel ranges from 0.67 to 0.88 in olivine-dunite, quite similar to that of the high-Cr chromitite, whereas it is around 0.62 in lherzolite-harzburgite. Primary hydrous mineral inclusions, amphibole and phlogopite, in chrome spinel have been reported for the first time from the Pan-African Proterozoic podiform chromitites. On the other hand, petrographic and geochemical evidence suggests that podiform chromitites in the SED of Egypt were formed as a result of crystallization of mafic melts, probably of boninitic composition, the boninitic parental magmas were probably produced by a second stage of melting above a subduction zone. Three types of chromite ores can be distinguished within the SED of Egypt: (a) sulphide-poor podiform ores; (b) brecciated ores; and (c) sulphide-rich ores. Two textural types of inclusions in chromite are distinguished: (1) primary silicate inclusions generally have high Mg-number (>96), Cr and Ni, and are dominated by pargasitic amphibole, forsterite, diopside, enstatite and Na-phlogopite. A diversity of primary and secondary platinum group minerals (PGM) is described from the chromitites, including alloys, sulphides, sulpharsenides and arsenides of Ru, Os, Ir, Rh, Ni, Cu, Fe and Co; (2) in addition to primary PGM and hydrous silicates, the fluids are of low to moderate salinity, sodium-dominated aqueous solutions with complex gas contents. Variable amounts of water, hydrogen, hydrocarbons, carbon dioxides and nitrogen have been determined in inclusion-rich samples. The chondritenormalized PGE patterns of lherzolite-harzburgite and olivine-dunite have negative Ir and Pt, and positive Pd and Au anomalies. Chromitites are homo-geneous in composition but texturally zoned on a large scale. They carry elevated IPGE, manifested in numerous, primary and secondary PGM phases. |
| 英文关键词 | chromite deposit ophiolite complex Southeastern Desert Egypt petrological and geochemical chara-cterristics and mineralization |
| 类型 | Article |
| 语种 | 英语 |
| 收录类别 | ESCI |
| WOS记录号 | WOS:000218254200002 |
| WOS类目 | Geochemistry & Geophysics |
| WOS研究方向 | Geochemistry & Geophysics |
| 资源类型 | 期刊论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/328776 |
| 作者单位 | [Saleh, Gehad M.] Nucl Mat Author, POB 530 El Maadi, Cairo, Egypt |
| 推荐引用方式 GB/T 7714 | Saleh, Gehad M.. The chromite deposits associated with ophiolite complexes, Southeastern Desert, Egypt: Petrological and geochemical characteristics and mineralization[J],2006,25(4):307-317. |
| APA | Saleh, Gehad M..(2006).The chromite deposits associated with ophiolite complexes, Southeastern Desert, Egypt: Petrological and geochemical characteristics and mineralization.ACTA GEOCHIMICA,25(4),307-317. |
| MLA | Saleh, Gehad M.."The chromite deposits associated with ophiolite complexes, Southeastern Desert, Egypt: Petrological and geochemical characteristics and mineralization".ACTA GEOCHIMICA 25.4(2006):307-317. |
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