Pub Date : 2019-01-01DOI: 10.21608/egjg.2019.216358
W. Elwan
Homrat El-Girigab area located at Northern Eastern Desert which, characterized by abundant intrusion of calc-alkaline and alkaline/peralkaline granitoids and their associated volcanics. These granitoids have a particular geodynamic interest as they provide an outstanding opportunity to tell how continental crust of ANS was formed. Homrat El-Girigab area is covered by Dokhan volcanics (andesite & dacites), which intruded by alkali-feldspar granites. The chemistry of biotites indicates that, the alkali-feldspar granites were crystallized from alkaline crustal source under oxidized conditions (i.e. nickel-nickel oxide buffer or NNO). They were crystallized under conditions including, temperatures range from 700 to 750 ̊C, pressures 3 to 4 kbar, depths of emplacement range from 7 to 11 km and under Oxygen fugacity (log fO2) ranges from -15 to -16. Homrat El-Girigab alkali-feldspar granites (HGAFGs) are alkaline, ferroan anorogenic (i.e. extensional) A-type granites. They were emplaced during the late post-collisional crustal extensional stage at which the effect of lithospheric delamination, and thus asthenospheric uprise, likely diminishes. At this stage the mantle-derived mafic melts start intraplating the lower crustal levels, that facilitated by the abundance of strike-slip faults and shear zones. This lithospheric intraplating caused widespread melting producing the alkaline magma of HGAFGs. The studied granites were derived from lower crustal amphibolitic source and evolved mainly by fractional crystallization.
{"title":"PETROGENESIS OF HOMRAT EL-GIRIGAB ALKALI-FELDSPAR GRANITES, NORTHERN EASTERN DESERT, EGYPT","authors":"W. Elwan","doi":"10.21608/egjg.2019.216358","DOIUrl":"https://doi.org/10.21608/egjg.2019.216358","url":null,"abstract":"Homrat El-Girigab area located at Northern Eastern Desert which, characterized by abundant intrusion of calc-alkaline and alkaline/peralkaline granitoids and their associated volcanics. These granitoids have a particular geodynamic interest as they provide an outstanding opportunity to tell how continental crust of ANS was formed. Homrat El-Girigab area is covered by Dokhan volcanics (andesite & dacites), which intruded by alkali-feldspar granites. The chemistry of biotites indicates that, the alkali-feldspar granites were crystallized from alkaline crustal source under oxidized conditions (i.e. nickel-nickel oxide buffer or NNO). They were crystallized under conditions including, temperatures range from 700 to 750 ̊C, pressures 3 to 4 kbar, depths of emplacement range from 7 to 11 km and under Oxygen fugacity (log fO2) ranges from -15 to -16. Homrat El-Girigab alkali-feldspar granites (HGAFGs) are alkaline, ferroan anorogenic (i.e. extensional) A-type granites. They were emplaced during the late post-collisional crustal extensional stage at which the effect of lithospheric delamination, and thus asthenospheric uprise, likely diminishes. At this stage the mantle-derived mafic melts start intraplating the lower crustal levels, that facilitated by the abundance of strike-slip faults and shear zones. This lithospheric intraplating caused widespread melting producing the alkaline magma of HGAFGs. The studied granites were derived from lower crustal amphibolitic source and evolved mainly by fractional crystallization.","PeriodicalId":282322,"journal":{"name":"Egyptian Journal of Geology","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128758040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.21608/egjg.2019.216330
S. Sabry, Helal
The main objective of the present study is to identify the Pliocene depositional channel and the gas behavior on seismic characteristics at the on-shore West El Qantara Region, in the eastern part of the Nile Delta Basin, using seismic reflection data and attributes analysis. The integrated use of seismic attributes (coherency, Amplitude Versus Offset “AVO” modeling and amplitude extraction) added information about the hydrocarbon seismic signature, facies and the minor geological structures. The 3D seismic interpretation results were correlated with the known regional structural–stratigraphic fashion of the onshore Nile Delta Basin and showed a satisfied matching, added more details about hydrocarbon signature.
本研究的主要目的是利用地震反射数据和属性分析，在尼罗河三角洲盆地东部的West El Qantara近海地区识别上新世沉积通道和天然气行为对地震特征的影响。综合利用地震属性(相干性、振幅相对偏移量“AVO”建模和振幅提取)，增加了油气地震特征、相和小型地质构造的信息。三维地震解释结果与已知的尼罗河三角洲盆地陆上区域构造-地层模式相匹配，显示出满意的匹配，为油气特征提供了更多细节。
{"title":"IMAGING THE PLIOCENE CHANNEL SYSTEM USING 3D SEISMIC ATTRIBUTES AT THE WEST EL QANTARA REGION, NILE DELTA BASIN, NORTHERN EGYPT","authors":"S. Sabry, Helal","doi":"10.21608/egjg.2019.216330","DOIUrl":"https://doi.org/10.21608/egjg.2019.216330","url":null,"abstract":"The main objective of the present study is to identify the Pliocene depositional channel and the gas behavior on seismic characteristics at the on-shore West El Qantara Region, in the eastern part of the Nile Delta Basin, using seismic reflection data and attributes analysis. The integrated use of seismic attributes (coherency, Amplitude Versus Offset “AVO” modeling and amplitude extraction) added information about the hydrocarbon seismic signature, facies and the minor geological structures. The 3D seismic interpretation results were correlated with the known regional structural–stratigraphic fashion of the onshore Nile Delta Basin and showed a satisfied matching, added more details about hydrocarbon signature.","PeriodicalId":282322,"journal":{"name":"Egyptian Journal of Geology","volume":"130 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132781593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.21608/egjg.2019.216363
Yasser A. El-Safori, A. Muftah
A taxonomic study has been performed for the thirty-two retrieve bryozoan species from the measured Serravallian Maradah Formation section at Z138, Jabal Zaltan, northeastern Sirt Basin, Libya. Among this unique assemblage only two new species Calpensia spinosa and Thalamoporella zaltaniensis have been established. The Cubitostrea shells provide the most attachments of the encrusting bryozoans. The reported species are of Mediterranean/Atlantic distributional affinity. However the new species are considered as an endemic species. The limestones and marls are rich in erect flexible and encrusting forms which indicate inter-subtidal (10-50m) environments with moderate rate of sedimentation and relatively strong wave actions. Highly agitated environment is specially recognized from the investigated assemblages in the lower part of Ar Rahlah Member of Maradah Formation as suggested on taphonomical basis.
{"title":"MIOCENE BRYOZOANS FROM JABAL ZALTAN, NORTHEAST SIRT BASIN, LIBYA","authors":"Yasser A. El-Safori, A. Muftah","doi":"10.21608/egjg.2019.216363","DOIUrl":"https://doi.org/10.21608/egjg.2019.216363","url":null,"abstract":"A taxonomic study has been performed for the thirty-two retrieve bryozoan species from the measured Serravallian Maradah Formation section at Z138, Jabal Zaltan, northeastern Sirt Basin, Libya. Among this unique assemblage only two new species Calpensia spinosa and Thalamoporella zaltaniensis have been established. The Cubitostrea shells provide the most attachments of the encrusting bryozoans. The reported species are of Mediterranean/Atlantic distributional affinity. However the new species are considered as an endemic species. The limestones and marls are rich in erect flexible and encrusting forms which indicate inter-subtidal (10-50m) environments with moderate rate of sedimentation and relatively strong wave actions. Highly agitated environment is specially recognized from the investigated assemblages in the lower part of Ar Rahlah Member of Maradah Formation as suggested on taphonomical basis.","PeriodicalId":282322,"journal":{"name":"Egyptian Journal of Geology","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117068417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.21608/egjg.2019.216329
El Motany, Helal
The main target of the present study is to identify the structure and the stratigraphic features associated with the potential traps by using the recent acquired 3D seismic data at the southern part of West El Qantara area in the Nile Delta Basin. The integrated usage of seismic attributes (Variance, Root Mean Square RMS and Amplitude Extraction) added significant information on the geological features, facies and the minor structures of the study area and consequently enhanced the hydrocarbon potentiality. The correlation of extracted depositional and structure models from the interpreted seismic data with the regional stratigraphic and structural setting of the Nile Delta showed a good match and led to a better understanding of the geological history and hydrocarbon potentiality of the study area. This consequently could be used as useful tool for future development in the study area.
本研究的主要目的是利用新近获得的尼罗河三角洲盆地West El Qantara地区南部的三维地震数据，识别与潜在圈闭相关的构造和地层特征。综合利用地震属性(方差、均方根RMS和振幅提取)，增加了研究区地质特征、相和次要构造的重要信息，从而提高了油气潜力。利用地震资料提取的沉积构造模型与尼罗三角洲区域地层构造背景进行对比，得到了较好的拟合结果，有助于更好地认识研究区地质历史和油气潜力。因此，这可以作为研究领域未来发展的有用工具。
{"title":"ENHANCEMENT OF THE 3D SEISMIC INTERPRETATION BY USING SEISMIC ATTRIBUTES AT THE SOUTHERN REGION OF WEST ELQANTARA, NILE DELTA, EGYPT","authors":"El Motany, Helal","doi":"10.21608/egjg.2019.216329","DOIUrl":"https://doi.org/10.21608/egjg.2019.216329","url":null,"abstract":"The main target of the present study is to identify the structure and the stratigraphic features associated with the potential traps by using the recent acquired 3D seismic data at the southern part of West El Qantara area in the Nile Delta Basin. The integrated usage of seismic attributes (Variance, Root Mean Square RMS and Amplitude Extraction) added significant information on the geological features, facies and the minor structures of the study area and consequently enhanced the hydrocarbon potentiality. The correlation of extracted depositional and structure models from the interpreted seismic data with the regional stratigraphic and structural setting of the Nile Delta showed a good match and led to a better understanding of the geological history and hydrocarbon potentiality of the study area. This consequently could be used as useful tool for future development in the study area.","PeriodicalId":282322,"journal":{"name":"Egyptian Journal of Geology","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133507814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.21608/egjg.2019.216357
Abdel-Hamid, A. Kader, El Manawi, A. Warith
Gabal Abu Hamr pluton is an elongated peralkaline granitic mass emplaced along the ENE-WSW Qena-Safaga shear zone as one of the anorogenic peralkaline granites represented in the Eastern Desert of Egypt. The rock is hypersolvus, composed of perthite, quartz and both alkali amphibole (arfvedsonite) and pyroxene (aegerine). It is enriched in Si, Na, K, Ba, Y, Ga and LREE and depleted in Al, Mg, Ca, Mn, Zr and HREE. The rocks exhibit mineralogical and chemical traits typical of within-plate A-type granites, which, due to the ascending of hydrothermal solutions along the ENE-WSW strike-slip fault, dividing the pluton, suffered metasomatic processes causing the leaching of Zr, U and HREE and their escape into the fluids and transported through the structure systems to be concentrated along the tectonic contact between the granite and the adjacent metavolcanics. This pluton may represent the northern extension of both G. Abu Kharif and G. El Dob being emplaced along the same E-NE shear zone trend. The suggested age of emplacement of G. Abu Hamr pluton is from 550 Ma to 450 Ma.
Gabal Abu Hamr岩体是沿ENE-WSW Qena-Safaga剪切带发育的细长过碱性花岗岩块体，是埃及东部沙漠典型的造山带过碱性花岗岩之一。岩石为超溶质，由花青石、石英和碱角闪石(亚铁榴辉岩)和辉石(绿辉岩)组成。富Si、Na、K、Ba、Y、Ga、LREE，贫Al、Mg、Ca、Mn、Zr、HREE。岩石具有典型的板内a型花岗岩的矿物学和化学特征，由于热液沿ENE-WSW走滑断裂上行，分裂岩体，发生交代作用，导致Zr、U、HREE浸出并逸出到流体中，通过构造体系运移，沿花岗岩与邻近变质火山的构造接触集中。该岩体可能代表了G. Abu Kharif和G. El Dob沿同一E-NE剪切带走向的北伸。推测G. Abu Hamr岩体的就位年龄在550 ~ 450 Ma之间。
{"title":"GABAL ABU HAMR PLUTON: AN EXAMPLE OF A-TYPE ANOROGENIC PERALKALINE GRANITES IN EGYPT","authors":"Abdel-Hamid, A. Kader, El Manawi, A. Warith","doi":"10.21608/egjg.2019.216357","DOIUrl":"https://doi.org/10.21608/egjg.2019.216357","url":null,"abstract":"Gabal Abu Hamr pluton is an elongated peralkaline granitic mass emplaced along the ENE-WSW Qena-Safaga shear zone as one of the anorogenic peralkaline granites represented in the Eastern Desert of Egypt. The rock is hypersolvus, composed of perthite, quartz and both alkali amphibole (arfvedsonite) and pyroxene (aegerine). It is enriched in Si, Na, K, Ba, Y, Ga and LREE and depleted in Al, Mg, Ca, Mn, Zr and HREE. The rocks exhibit mineralogical and chemical traits typical of within-plate A-type granites, which, due to the ascending of hydrothermal solutions along the ENE-WSW strike-slip fault, dividing the pluton, suffered metasomatic processes causing the leaching of Zr, U and HREE and their escape into the fluids and transported through the structure systems to be concentrated along the tectonic contact between the granite and the adjacent metavolcanics. This pluton may represent the northern extension of both G. Abu Kharif and G. El Dob being emplaced along the same E-NE shear zone trend. The suggested age of emplacement of G. Abu Hamr pluton is from 550 Ma to 450 Ma.","PeriodicalId":282322,"journal":{"name":"Egyptian Journal of Geology","volume":"236 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116330165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.21608/egjg.2019.216332
Amgad Soliman, M. Yousef, Y. E. Safori
Since the first hydrocarbon discovery in the Western Desert in 1969, several papers were published focusing on the conventional petroleum system elements. The entire stratigraphic section was studied to define the source rocks, seals and reservoirs. The present work focuses on screening the available dataset and re-using the geological information to assess the possible unconventional hydrocarbon resources. Geochemical analyses of the hydrocarbon rich stratigraphic intervals could lead to define and rank the shale oil and gas plays in terms of their presence, type, quality and lateral extension. Both major source rocks(Abu Roash and Khatatba formations) went through many geological and geochemical studies that proved their efficiency and ability to produce oil, gas, and condensate in different localities based on their maturation, total organic content, hydrogen index and kerogen type. Preliminary screening of the stratigraphy and geochemistry of the Western Desert source rocks indicated the shale gas and oil potential of the Abu Roash source rock in the Abu Gharadig Basin. The parameters required to assess the shale oil/gas plays are depth, thickness, lithological content, total organic content and maturation. In this paper, the available geochemical data were collected, screened and plotted to indicate the possible unconventional hydrocarbon plays.
{"title":"SHALE OIL AND GAS PROSPECTIVITY OF THE NORTHERN WESTERN DESERT, EGYPT","authors":"Amgad Soliman, M. Yousef, Y. E. Safori","doi":"10.21608/egjg.2019.216332","DOIUrl":"https://doi.org/10.21608/egjg.2019.216332","url":null,"abstract":"Since the first hydrocarbon discovery in the Western Desert in 1969, several papers were published focusing on the conventional petroleum system elements. The entire stratigraphic section was studied to define the source rocks, seals and reservoirs. The present work focuses on screening the available dataset and re-using the geological information to assess the possible unconventional hydrocarbon resources. Geochemical analyses of the hydrocarbon rich stratigraphic intervals could lead to define and rank the shale oil and gas plays in terms of their presence, type, quality and lateral extension. Both major source rocks(Abu Roash and Khatatba formations) went through many geological and geochemical studies that proved their efficiency and ability to produce oil, gas, and condensate in different localities based on their maturation, total organic content, hydrogen index and kerogen type. Preliminary screening of the stratigraphy and geochemistry of the Western Desert source rocks indicated the shale gas and oil potential of the Abu Roash source rock in the Abu Gharadig Basin. The parameters required to assess the shale oil/gas plays are depth, thickness, lithological content, total organic content and maturation. In this paper, the available geochemical data were collected, screened and plotted to indicate the possible unconventional hydrocarbon plays.","PeriodicalId":282322,"journal":{"name":"Egyptian Journal of Geology","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124659727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.21608/egjg.2019.216359
El Afandy, El Shaib
Pegmatitic bodies are encountered within the Kadabora granite to which they are spatially and genetically related. These bodies bearing REEs, U, Th, Y, Zr, Hf, Nb, Ta, and Cs. The mineralized pegmatites are characterized by high ΣREEs contents ranging from 3404 ppm to 15196 with an average of 7516ppm. The assemblage of the accessory minerals encountered in the mineralized pegmatites are zircon, allanite, fergusonite, uranothorite, betafite, samarskite, pyrochlore, bastnaesite, cerianite, rutile, euxenite and opaques. Each of these minerals is bearing certain trace elements ; zircon (Zr, Hf , Th); fergusonite (U, Th, Zr); uranothorite (Th, U); betafite (U, Nb, Ta); samarskite (Nb, Ta, U); pyrochlore (Nb, Ta); bastnaesite (REEs); cerianite (Ce, Th, Nb, Ta, Zr) and rutile (Ti). The REEs distribution pattern in the mineralized pegmatites reflects the role of these minerals as REEs accumulators e. g. betafite, bastnaesite and cerianite host LREEs while zircon, allanite and samarskite host HREEs. The REEs pattern is characterized by HREEs enrichment relative to LREEs with convex tetrad effect and a sharp negative Eu anomaly. This well demonstrated pattern reflects highly differentiated rocks associated with self strong hydrothermal interaction. It seems that parent magma has undergone extensive magmatic differentiation, during associated with syngenetic interaction of aqueous hydrothermal fluids resulted in the tetrad effect of REEs distribution forming highly mineralized pegmatites.
{"title":"GEOCHEMICAL CONTRIBUTIONS OF REE'S BEARING PEGMATITES, WITHIN KADABORA GRANITIC PLUTON, CENTRAL EASTERN DESERT, EGYPT","authors":"El Afandy, El Shaib","doi":"10.21608/egjg.2019.216359","DOIUrl":"https://doi.org/10.21608/egjg.2019.216359","url":null,"abstract":"Pegmatitic bodies are encountered within the Kadabora granite to which they are spatially and genetically related. These bodies bearing REEs, U, Th, Y, Zr, Hf, Nb, Ta, and Cs. The mineralized pegmatites are characterized by high ΣREEs contents ranging from 3404 ppm to 15196 with an average of 7516ppm. The assemblage of the accessory minerals encountered in the mineralized pegmatites are zircon, allanite, fergusonite, uranothorite, betafite, samarskite, pyrochlore, bastnaesite, cerianite, rutile, euxenite and opaques. Each of these minerals is bearing certain trace elements ; zircon (Zr, Hf , Th); fergusonite (U, Th, Zr); uranothorite (Th, U); betafite (U, Nb, Ta); samarskite (Nb, Ta, U); pyrochlore (Nb, Ta); bastnaesite (REEs); cerianite (Ce, Th, Nb, Ta, Zr) and rutile (Ti). The REEs distribution pattern in the mineralized pegmatites reflects the role of these minerals as REEs accumulators e. g. betafite, bastnaesite and cerianite host LREEs while zircon, allanite and samarskite host HREEs. The REEs pattern is characterized by HREEs enrichment relative to LREEs with convex tetrad effect and a sharp negative Eu anomaly. This well demonstrated pattern reflects highly differentiated rocks associated with self strong hydrothermal interaction. It seems that parent magma has undergone extensive magmatic differentiation, during associated with syngenetic interaction of aqueous hydrothermal fluids resulted in the tetrad effect of REEs distribution forming highly mineralized pegmatites.","PeriodicalId":282322,"journal":{"name":"Egyptian Journal of Geology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129442842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.21608/egjg.2019.216355
B. R. Bakhit
Fluorite of different colours occurs as disseminations and veinlets in the host granitic rocks in ElMissikat area, central Eastern Desert, Egypt. This paper addresses the mineralogical and geochemical characteristics, including mineral chemistry, whole rock geochemical analyses of the granitic host rock. Trace, REY (REE+Y) elements, fluid inclusions and LA-ICP-MS analyses for individual fluid inclusions in fluorite were also carried out. Petrographically, the host granite represented by biotite granite. Mineral chemistry data of primary phases are given. Plagioclase is albite (average 2.79 mol%). Biotite is of primary magmatic origin and crystallized at 500 600C. Geochemically, El-Missikat granite is peraluminous Atype and was generated in post-collision environment (within plate). The average ΣREE content of Type V (violet), G (green) and Type W (white) fluorite samples are 75.5, 200.9 and 203.2 ppm, respectively (i.e. increasing from violet fluorite to green and white fluorites. These differences in ΣREE were possibly related to changes in pH condition and bulk chemical composition of the fluids. Tb/Ca, Tb/La and Y/Ho ratios of the fluorite types indicate that they were formed from the interaction between magmatic fluids and granitic wall-rocks. The fluorites show strongly negative Eu and positive Y anomalies similar to REY pattern of the host granites, indicating that the source of REE and trace elements of hydrothermal fluids is the host granite leached by fluids. The present work revealed that the contents of Y and total REE contents are responsible for the appearance of green and white colours. The Sr content is high in violet fluorite and may be responsible for violet colour. The fluid inclusions (FI) of the fluorite have homogenisation temperatures ranging from 201C to 296C in Type A (high salinity FI) and 160C to 165C in Type B (low salinity FI). The melting temperature of ice in fluorite indicates salinities up to 19.4 equiv. wt% Na CI (Type A) but Type B FI have a low range of salinity (0.53 to 4.49 equiv. wt% Na Cl). The density of fluids is 0.9 to 1.0 g/cm in Type A and 0.9 g/cm in Type B. From the LA-ICP-MS data for the individual FI of El-Missikat fluorite, it is clear that the Type A FI contains very high concentrations of elements than that in Type B FI. The abundance of the analyzed elements in the present FI is: Ca > Na > S > K > Sr > Y > Fe, Pb > Cu > U > Cs, W, Te, Ag, As > Th > Au. The deposition mechanisms for fluorite may be fluid mixing, changes in pressure and temperature and fluid-rock interaction.
在埃及东部沙漠中部的ElMissikat地区，不同颜色的萤石以浸染状和细脉状的形式出现在寄主花岗岩中。本文论述了该花岗质寄主岩的矿物学和地球化学特征，包括矿物化学、全岩地球化学分析。对萤石中单个流体包裹体进行了痕量、REY (REE+Y)元素、流体包裹体和LA-ICP-MS分析。岩石学上，寄主花岗岩以黑云母花岗岩为代表。给出了原生相的矿物化学数据。斜长石为钠长石(平均2.79 mol%)。黑云母为原生岩浆成因，在500 ~ 600℃结晶。地球化学特征表明，El-Missikat花岗岩为过铝质花岗岩，形成于碰撞后(板块内)环境。V型(紫色)、G型(绿色)和W型(白色)萤石样品的平均ΣREE含量分别为75.5、200.9和203.2 ppm(即从紫色萤石逐渐增加到绿色和白色萤石)。ΣREE的这些差异可能与pH条件和流体的总体化学成分的变化有关。萤石类型的Tb/Ca、Tb/La和Y/Ho比值表明它们是岩浆流体与花岗质围岩相互作用形成的。萤石表现出强烈的Eu负异常和Y正异常，与寄主花岗岩的REY异常相似，表明热液流体中稀土元素和微量元素的来源是流体浸出的寄主花岗岩。目前的研究表明，稀土元素的含量和总稀土元素的含量是造成绿色和白色外观的原因。紫色萤石中锶含量高，可能是紫色的原因。A型萤石流体包裹体(FI)均质温度为201C ~ 296C(高盐度FI)， B型萤石流体包裹体(FI)均质温度为160C ~ 165C(低盐度FI)。萤石中冰的熔化温度表明其盐度可达19.4等wt% Na CI (A型)，但B型FI的盐度范围较低(0.53 ~ 4.49等wt% Na Cl)。A型流体密度为0.9 ~ 1.0 g/cm, B型流体密度为0.9 g/cm。从El-Missikat萤石单个FI的LA-ICP-MS数据可以清楚地看出，A型FI比B型FI含有非常高浓度的元素。分析元素的丰度为:Ca > Na > S > K > Sr > Y > Fe, Pb > Cu > U > Cs, W, Te, Ag, As > Th > Au。萤石的沉积机制可能是流体混合、压力和温度变化以及流体-岩石相互作用。
{"title":"MINERALOGICAL AND GEOCHEMICAL CHARACTERISTICS OF EL-MISSIKAT FLUORITE MINERALIZATION, CENTRAL EASTERN DESERT, EGYPT: TRACE ELEMENTS AND FLUID INCLUSIONS CONSTRAINTS","authors":"B. R. Bakhit","doi":"10.21608/egjg.2019.216355","DOIUrl":"https://doi.org/10.21608/egjg.2019.216355","url":null,"abstract":"Fluorite of different colours occurs as disseminations and veinlets in the host granitic rocks in ElMissikat area, central Eastern Desert, Egypt. This paper addresses the mineralogical and geochemical characteristics, including mineral chemistry, whole rock geochemical analyses of the granitic host rock. Trace, REY (REE+Y) elements, fluid inclusions and LA-ICP-MS analyses for individual fluid inclusions in fluorite were also carried out. Petrographically, the host granite represented by biotite granite. Mineral chemistry data of primary phases are given. Plagioclase is albite (average 2.79 mol%). Biotite is of primary magmatic origin and crystallized at 500 600C. Geochemically, El-Missikat granite is peraluminous Atype and was generated in post-collision environment (within plate). The average ΣREE content of Type V (violet), G (green) and Type W (white) fluorite samples are 75.5, 200.9 and 203.2 ppm, respectively (i.e. increasing from violet fluorite to green and white fluorites. These differences in ΣREE were possibly related to changes in pH condition and bulk chemical composition of the fluids. Tb/Ca, Tb/La and Y/Ho ratios of the fluorite types indicate that they were formed from the interaction between magmatic fluids and granitic wall-rocks. The fluorites show strongly negative Eu and positive Y anomalies similar to REY pattern of the host granites, indicating that the source of REE and trace elements of hydrothermal fluids is the host granite leached by fluids. The present work revealed that the contents of Y and total REE contents are responsible for the appearance of green and white colours. The Sr content is high in violet fluorite and may be responsible for violet colour. The fluid inclusions (FI) of the fluorite have homogenisation temperatures ranging from 201C to 296C in Type A (high salinity FI) and 160C to 165C in Type B (low salinity FI). The melting temperature of ice in fluorite indicates salinities up to 19.4 equiv. wt% Na CI (Type A) but Type B FI have a low range of salinity (0.53 to 4.49 equiv. wt% Na Cl). The density of fluids is 0.9 to 1.0 g/cm in Type A and 0.9 g/cm in Type B. From the LA-ICP-MS data for the individual FI of El-Missikat fluorite, it is clear that the Type A FI contains very high concentrations of elements than that in Type B FI. The abundance of the analyzed elements in the present FI is: Ca > Na > S > K > Sr > Y > Fe, Pb > Cu > U > Cs, W, Te, Ag, As > Th > Au. The deposition mechanisms for fluorite may be fluid mixing, changes in pressure and temperature and fluid-rock interaction.","PeriodicalId":282322,"journal":{"name":"Egyptian Journal of Geology","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130236452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.21608/egjg.2019.216347
Soliman, El Sandouly
Abu Harba area is located in the North Eastern Desert (NED) which mainly covered by metavolcanics, Dokhan volcanics, metagabbro-diorite complex and younger granites. The detailed structural analysis of Abu Harba area indicate that shear stress trending NNE-SSW and NW-SE directions represent nearly the the Gulf of Aqaba and the Gulf of Suez trends. The lineaments in the area are multidirectional orientation with three main trends; ENE-WSW, NE-SW and E-W with less dominant trends represented by N-S, NNW-SSE and NW-SE directions. The mineralizations of secondary uranium (uranophane, kasolite and betafite) in Abu Harba area seem to be lithologically and structurally controlled. The alkali feldspar granites in the area contain highly amounts of silica and alkalis, accessory minerals and iron oxides. On the other hand, the NE-SW lineaments in the study area allowed the hydrothermal solution that bear uranium minerals to infiltrate upwardly parallel faults and joint sets at the peripheral western part of G. Abu Harba alkali feldspar granites. As the faults are suitable places for the flow of hydrothermal solutions bearing mineralization. So, the mineralizations appear to be structurally controlled.
Abu Harba地区位于东北沙漠(NED)，主要发育变质火山、Dokhan火山、变质闪长岩杂岩和年轻花岗岩。详细的构造分析表明，Abu Harba地区的剪应力走向NNE-SSW和NW-SE方向接近亚喀巴湾和苏伊斯湾走向。区内地貌呈多向取向，主要有三种走向;ENE-WSW、NE-SW和E-W方向不占优势，以N-S、NNW-SSE和NW-SE方向为代表。Abu Harba地区次生铀(铀矿石、钾辉石和倍辉石)的成矿作用似乎受岩性和构造控制。该地区碱长石花岗岩含有大量的硅、碱、副矿物和氧化铁。另一方面，研究区NE-SW向的构造构造使含铀矿物的热液能够渗透到G. Abu Harba碱性长石花岗岩西部外围向上平行的断裂和节理套中。断层是含矿热液流动的适宜场所。因此，矿化似乎受构造控制。
{"title":"STRUCTURAL CONTROLS ON MINERALIZATIONS AT ABU HARBA AREA, NORTH EASTERN DESERT, EGYPT","authors":"Soliman, El Sandouly","doi":"10.21608/egjg.2019.216347","DOIUrl":"https://doi.org/10.21608/egjg.2019.216347","url":null,"abstract":"Abu Harba area is located in the North Eastern Desert (NED) which mainly covered by metavolcanics, Dokhan volcanics, metagabbro-diorite complex and younger granites. The detailed structural analysis of Abu Harba area indicate that shear stress trending NNE-SSW and NW-SE directions represent nearly the the Gulf of Aqaba and the Gulf of Suez trends. The lineaments in the area are multidirectional orientation with three main trends; ENE-WSW, NE-SW and E-W with less dominant trends represented by N-S, NNW-SSE and NW-SE directions. The mineralizations of secondary uranium (uranophane, kasolite and betafite) in Abu Harba area seem to be lithologically and structurally controlled. The alkali feldspar granites in the area contain highly amounts of silica and alkalis, accessory minerals and iron oxides. On the other hand, the NE-SW lineaments in the study area allowed the hydrothermal solution that bear uranium minerals to infiltrate upwardly parallel faults and joint sets at the peripheral western part of G. Abu Harba alkali feldspar granites. As the faults are suitable places for the flow of hydrothermal solutions bearing mineralization. So, the mineralizations appear to be structurally controlled.","PeriodicalId":282322,"journal":{"name":"Egyptian Journal of Geology","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121537375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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