Geochemistry of lamprophyre dykes, Wadi Sikait area, South Eastern Desert, Egypt

来源 :Chinese Journal of Geochemistry | 被引量 : 0次 | 上传用户:hubaonian
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
The Wadi Sikait area lies at about 95 km southwest of Marsa Alam City along the Red Sea Coast, Eastern Desert, Egypt. It is occupied by Precambrian rocks of ophiolitic mélange, metamorphosed sandstones (MSS), gab-bros and monzogranites which were later intruded by lamprophyre dykes and quartz veins. The lamprophyre dykes were extruded in NW-SE and NE-SW trends cutting monzogranites and metamor-phosed sandstones. The lamprophyres are porphyritic and composed of clinopyroxene, olivine and amphibole phenocrysts enclosed in a fine-grained groundmass of clinopyroxene, amphibole, opaque and lithium mica. The al-teration products are represented by amphibole (tremolite-actinolite and hornblende), carbonate, epidote, chlorite, iddingsite, clay minerals, limonite and serpentine. The Sikait lamprophyre dykes can be classified as alkaline lamprophyres characterized by silica contents rang-ing from 41.65 wt% to 50.88 wt% and Na2O>K2O. They are enriched in LILE, LREE and HFSE, but strongly de-pleted in compatible elements such as Cr and Ni relative to the primitive mantle. Sikait lamprophyres have moderate Zr/Hf (35.6-52.8) and Nb/Ta (20.5-22.5) ratios. Most of these features are attributed to the origin of these dykes from the metasomatized mantle affected by subduction-related fluid. These lamprophyres are compositionally similar to Salu lamprophyres in eastern China. The Sikait lamprophyre samples have high LREE (320×10-6-419×10-6) relative to HREE (20×10-6-33×10-6) with ratios (LREE/HREE=11.6-18.7) and no negative Eu anomaly (Eu/Eu*=0.9-1.04). The relative presence of posi-tive Ce anomaly (Ce/Ce*=1.04) in lamprophyre samples suggests the oxidizing condition under which the REEs were precipitated due to the common occurrence of fluorite and apatite. The Wadi Sikait area lies at about 95 km southwest of Marsa Alam City along the Red Sea Coast, Eastern Desert, Egypt. It is occupied by Precambrian rocks of ophiolitic mélange, metamorphosed sandstones (MSS), gab-bros and monzogranites which were later intruded by lamprophyre dykes and quartz veins. The lamprophyre dykes were extruded in NW-SE and NE-SW trends cutting monzogranites and metamor-phosed sandstones. The lamprophyres are porphyritic and composed of clinopyroxene, olivine and amphibole phenocrysts enclosed in a fine-grained groundmass of clinopyroxene, amphibole, opaque and lithium mica. The al-teration products are represented by amphibole (tremolite-actinolite and hornblende), carbonate, epidote, chlorite, iddingsite, clay minerals, limonite and serpentine. The Sikait lamprophyre dykes can be classified as alkaline lamprophyres characterized by silica content rang-ing from 41.65 wt% to 50.88 wt% and Na2O> K2O. They are enriched in LILE, LREE and HFSE, but strongly de-plet ed in compatible elements such as Cr and Ni relative to the primitive mantle. Sikait lamprophyres have moderate Zr / Hf (35.6-52.8) and Nb / Ta (20.5-22.5) ratios. Most of these features are attributed to the origin of these dykes from the metasomatized mantle affected by subduction-related fluid. These lamprophyres are compositionally similar to Salu lamprophyres in eastern China. The Sikait lamprophyre samples have high LREE (320 × 10-6-419 × 10-6) relative to HREE (20 × 10 6-33 × 10-6 with ratios (LREE / HREE = 11.6-18.7) and no negative Eu anomaly (Eu / Eu * = 0.9-1.04). The relative presence of posi-tive Ce anomaly (Ce / Ce * = 1.04) in lamprophyre samples suggests the oxidizing condition under which the REEs were precipitated due to the common occurrence of fluorite and apatite.
其他文献
该项目是为解决水库坝基深厚砂卵石层的防渗问题而提出的,是科研与生产相结合的实例.通过试验研究,可以把成功的理论及经验直接应用到水库大坝砂卵石层基础的防渗处理上,同时
由于目前私家车购买比例的迅速上升,汽车经销商之间的竞争也越来越激烈,如何尽可能的获取汽车潜在消费者变得尤为重要.通过利用国家统计局的“私家车预购数据”,用支持向量机
为提高产学合作中知识转移绩效评价的科学性,分析了产学合作中的知识转移过程,结合知识转移的特点运用层次分析法确定评价指标体系,然后采用模糊综合评价的方法构建了评价模
在我国,FDI资本和国内民营资本在行业准入、融资等许多方面,都面临着截然不同的待遇.一个重要的原因在于,国内一般认为FDI的技术溢出效应显著,而国内民营资本则是落后技术的
目的 构建表达甲型H1N1流感病毒血凝素(hemagglutinin,HA)抗原的DNA疫苗,并在小鼠中测试其免疫原性.方法 运用人密码子优化技术合成甲型H1N1流感病毒HA序列,并转移至DNA疫苗
简述了萍乡湘东“12.20”森林火灾发生地基本情况及扑火经过,总结分析了如何根据火场的山形地貌、气象因子、扑火队伍的作战能力,运用正确的战略战术,合理用兵、科学指挥,在
本文基于笔者多年从事地形测量的相关工作经验,以广州市某镇土地整理项目为研究背景,分析了RTK技术在地形图测绘方面的应用情况,探讨了RTK与全站仪联合数据采集在地形图测绘方面的优越性,并对其精度进行了分析。全文是笔者长期工作实践基础上的理论升华,相信对从事相关工作的同行能有所裨益。
QuickBird卫星是目前具有较高空间分辨率的商业卫星之一.由QuickBird卫星获取的原始遥感影像只进行了辐射校正和传感器校正,几何变形较大,无法满足用户的实际需求,需要作进一
The Ordos Basin of North China is not only an important uranium mineralization province,but also a major producer of oil,gas and coal in China.The genetic relat
This study is concerned with the radioactivity and mineralogy of the younger granites and pegmatites in the Wadi Haleifiya area,southeastern Sinai Peninsula,Egy