Ocellar lamprophyre dyke bearing mineralization,Wadi Nugrus,Eastern Desert,Egypt: Geology,mineralogy and geochemical implications |
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Authors: | M E Ibrahim G M Saleh N A Dawood G M Aly |
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Institution: | 1.Nuclear Materials Authority,El-Maadi, Cairo,Egypt |
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Abstract: | The ocellar lamprophyre dyke (ENE-WSW) is recorded at Wadi Nugrus, Eastern Desert, Egypt. It cuts porphyritic biotite granites
and varies in thickness from 0.5 to 1.5 m and up to 3 km in length. The 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 composition. Rutile, titanite, apatite, fluorite, graphite, calcite, allanite, autunite and Fe-Ti oxides
are accessory minerals. Kaolinite, chlorite and epidote are secondary minerals. Carbonitization and hematitization are common.
Rounded to sub-rounded porphyritic and zoned ocelli with radiate or brush-like shapes are generally common and represent physical
traps for mineralization. The ocellar features are interpreted to represent the late stage of magmatic segregation or magmatic
crystallization involving two immiscible magmatic liquids. |
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