Petrographic and mineralogic studies of the layered intrusions at Jabal El-Ekeim, Saudi Arabia
Jabal El-Ekeim consists of two differently sized coalescing mafic-ultramafic layered intrusions. The large intrusion is divided into sixteen units, while the smaller one is divided into fourteen units. This classification depends on their cumulus crystals and post-cumulus material. Both intrusions c...
Elmentve itt :
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| Dokumentumtípus: | Cikk |
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University of Szeged, Department of Mineralogy, Geochemistry and Petrology
Szeged
1999
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| Sorozat: | Acta mineralogica-petrographica
40 |
| Kulcsszavak: | Kőzettan, Ásványtan, Földtan |
| Tárgyszavak: | |
| Online Access: | http://acta.bibl.u-szeged.hu/24878 |
| Tartalmi kivonat: | Jabal El-Ekeim consists of two differently sized coalescing mafic-ultramafic layered intrusions. The large intrusion is divided into sixteen units, while the smaller one is divided into fourteen units. This classification depends on their cumulus crystals and post-cumulus material. Both intrusions consist of concentric layers dipping radially inwards and have a higher dip at the periphery. The large intrusion has a boat like shape elongated in a NW-SE direction, while the small one has a subcircular shape and is elongated in a NE-SW direction perpendicular to the elongation of the large one. It could be concluded that the elongations of the two intrusions are parallel to main structural trends in the investigated area. Slump structure, igneous lamination, knobby texture and micro and macrorhythmic layering are the main internal structures distinguish the rocks of the area under inspection. Their formations could be attributed to the combination of different mechanisms of density gravitational stratification and crystal sorting by magnetic concvection currents. r El-Ekeim intrusions include seven rock types: olivine gabbro, troctolite, hornblende-olivine gabbro, olivine gabbronorite, gabbro, anorthosite and peridotite. The essential minerals of El-Ekeim rocks are: plagioclase, olivine, clinopyroxene, orthopyroxene and hornblende. These minerals occur as cumulus and intercumulus phases. The accessory minerals are: biotite, apatite and opaques. The latters consist principally of iron-titanium oxides as magnetite, chromomagnetite, ilmenite, hematite, spinel and hemoilmenite. Sulphides as chalcopyrite, pyrrhotite, pyrite and pentlandite are also present. The mineral composition of both intrusions indicates that their parent magmas were similar and had a tholeiitic nature. The economic potential of these two intrusions at El-Ekeim is very poor with no signs for concentrations of ore minerals. Keywords: El-Ekeim two mafic ultramafic layered intrusions. Cumulus and intercumulus, seven rock types, tholeiitic nature, poor economic potentials. |
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| Terjedelem/Fizikai jellemzők: | 55-70 |
| ISSN: | 0365-8066 |