| Serpentinized Peridotites at the North Part of the Wadi Allaqi District (Egypt): Implications for the Tectono-Magmatic Evolution of Fore-arc Crust |
| |
| 作者姓名： | Ahmed E.S. KHALIL Mohamed A. OBEID and Mokhles K. AZER |
| |
| 作者单位： | 1 Geological Sciences Department, National Research Centre, P.O.Box 12622-Dokki, Cairo, Egypt
2 Geology Department, Faculty of Science, Fayoum University, P.O.Box 63514- Fayoum, Egypt |
| |
| 摘 要： | The Neoproterozoic Allaqi-Heiani suture （800-700 Ma） in the south Eastern Desert of Egypt is the northernmost linear ophiolitic belt that defines an arc-arc suture in the Arabian- Nubian shield （ANS）. The Neoproterozoic serpentinized peridotites represent a distinct lithology of dismembered ophiolites along the Allaqi-Heiani suture zone. The alteration of peridotites varies, some contain relicts of primary minerals （Cr-spinel and olivine） and others are extremely altered, especially along thrusts and shear zones, with development of talc, talc-carbonate and quartz-carbonate. The fresh cores of the chromian spinels are rimmed by ferritchromite and Cr- magnetite. The fresh chromian spinels have high Cr# （0.62 to 0.79）, while Mg# shows wider variation （0.35-0.59）. High Cr# in the relict chromian spinels and Fo content in the primary olivines indicate that they are residual peridotites after extensive partial melting. The studied ophiolitic upper mantle peridotites are highly depleted and most probably underwent high degrees of partial melting at a supra-subduction zone setting. They can be produced by up to -20%-22% dynamic melting of a primitive mantle source. The mineralogical and geochemical features of the studied rocks reflect that the mantle peridotites of the north part of the Wadi Allaqi district are similar to the fore-arc peridotites of a supra-subduction zone.
|
| 关 键 词： | 地幔橄榄岩 蛇纹石化 岩浆演化 埃及 构造 地壳 蛇绿岩带 铬尖晶石 |
| 收稿时间： | 2013/7/27 0:00:00 |
| 修稿时间： | 8/8/2014 12:00:00 AM |
Serpentinized Peridotites at the North Part of the Wadi Allaqi District (Egypt): Implications for the Tectono-Magmatic Evolution of Fore-arc Crust |
| |
| Authors: | Ahmed ESKHALIL Mohamed AOBEID Mokhles KAZER |
| |
| Institution: | 1. Geological Sciences Department, National Research Centre, P.O.Box 12622-Dokki, Cairo, Egypt
2. Geology Department, Faculty of Science, Fayoum University, P.O.Box 63514-Fayoum, Egypt |
| |
| Abstract: | The Neoproterozoic Allaqi‐Heiani suture (800–700 Ma) in the south Eastern Desert of Egypt is the northernmost linear ophiolitic belt that defines an arc‐arc suture in the Arabian‐Nubian shield (ANS). The Neoproterozoic serpentinized peridotites represent a distinct lithology of dismembered ophiolites along the Allaqi‐Heiani suture zone. The alteration of peridotites varies, some contain relicts of primary minerals (Cr‐spinel and olivine) and others are extremely altered, especially along thrusts and shear zones, with development of talc, talc‐carbonate and quartz‐carbonate. The fresh cores of the chromian spinels are rimmed by ferritchromite and Cr‐magnetite. The fresh chromian spinels have high Cr# (0.62 to 0.79), while Mg# shows wider variation (0.35–0.59). High Cr# in the relict chromian spinels and Fo content in the primary olivines indicate that they are residual peridotites after extensive partial melting. The studied ophiolitic upper mantle peridotites are highly depleted and most probably underwent high degrees of partial melting at a supra‐subduction zone setting. They can be produced by up to ～20%–22% dynamic melting of a primitive mantle source. The mineralogical and geochemical features of the studied rocks reflect that the mantle peridotites of the north part of the Wadi Allaqi district are similar to the fore‐arc peridotites of a supra‐subduction zone. |
| |
| Keywords: | Neoproterozoic serpentinite Arabian-Nubian Shield Egypt Chromian spinel olivine fore-arc |
| 本文献已被 CNKI 维普 万方数据 等数据库收录！ |
| 点击此处可从《Acta Geologica Sinica》浏览原始摘要信息 |
| 点击此处可从《Acta Geologica Sinica》下载免费的PDF全文 |
