Ocellar lamprophyre dyke bearing mineralization,Wadi Nugrus,Eastern Desert,Egypt:Geology,mineralogy and geochemical implications

作     者：Ibrahim M.E. Saleh G.M. Dawood N.A. Aly G.M. 

作者机构：Nuclear Materials AuthorityP.O.Box 530El-MaadiCairoEgypt 

出 版 物：《Chinese Journal Of Geochemistry》 (中国地球化学学报)

年 卷 期：2010年第29卷第4期

页      面：383-392页

核心收录：

学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

主　　题：煌斑岩脉 矿物学 地球化学 沙漠 埃及 地质学 黑云母花岗岩 矿化 

摘      要：The ocellar lamprophyre dyke(ENE-WSW) is recorded at Wadi Nugrus,Eastern Desert,*** cuts porphyritic biotite granites and varies in thickness from 0.5 to 1.5 m and up to 3 km in *** lamprophyre dyke has been altered,and it is characterized by porphyritic and panidiomorphic textures with plagioclase,olivine,and augite constituting the porphyritic phase in a fine groundmass of the same ***,titanite,apatite,fluorite,graphite,calcite,allanite,autunite and Fe-Ti oxides are accessory ***,chlorite and epidote are secondary *** and hematitization are *** to sub-rounded porphyritic and zoned ocelli with radiate or brush-like shapes are generally common and represent physical traps for *** ocellar features are interpreted to represent the late stage of magmatic segregation or magmatic crystallization involving two immiscible magmatic *** studies of altered lamprophyre samples,based on X-ray diffraction(XRD) and environmental scanning electron microscopy(ESEM),indicate the presence of secondary uranium minerals(autunite and uranophane),associated with gold,silver,nickel,atacamite,molybdenum,pyrite and *** presence of kaolinite indicates a high temperature *** mixing of volatile fluids with meteoric water and fluid-wall rock interaction result in changes of pH and oxygen activity and deposition of base metals in reducing environs(graphite and pyrite).Precipitation of hematite probably decreased the pH of the solution and rose acidic *** sudden change in pH and temperature of the fluids would lead to destabilization of base metal complexes favoring their *** magma source of the Nugrus lamprophyre is determined to be between calc-alkaline and alkaline and it has HKCAB and shoshonitic nature and may be derived from decomposition melting of such a metasomatised lithospheric *** is a major fractional phase to account for a rapid