Magmatism in the Cretaceous sedimentary basins of the Figuil and Léré regions constitutes one of the fundamental parameters in the reconstruction of the history of the Cretaceous sedimentary basins. The main...Magmatism in the Cretaceous sedimentary basins of the Figuil and Léré regions constitutes one of the fundamental parameters in the reconstruction of the history of the Cretaceous sedimentary basins. The main objective of this paper is to constrain the petrogenetic processes of hypovolcanic rocks and to determine their geodynamic context of emplacement. The petrographic study of mafic hypovolcanic and trachytic rocks was carried out under a polarizing microscope on thin sections. For the geochemical study, the major oxides and some trace elements were analyzed by ICP-AES. Trace and rare earth elements were analyzed by ICP-MS. The dolerites of the Cretaceous sedimentary basins are composed of dykes of amphibole bearing dolerites, biotite and pyroxene bearing dolerite, pyroxene bearing dolerites and trachytes. The dykes are in the order of 20 to 100 m wide by several kilometers long and oriented from N23<span style="white-space:normal;"><span style="white-space:normal;"><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span></span></span>E to N90<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>E. The textures of these rocks are sub-ophitic to intergranular for dolerites and trachytic for evolved rocks (trachytes). The geochemical study shows that the dolerites are basaltic in composition with alkaline to subalkaline character. The sampled dykes have an evolution dominated by fractional with the minor impact of the crustal assimilation characterized by low Rb/Y ratios for dolerites (0.36 - 0.97) and high values of Rb/Y for the Pan-African granitoid<span style="font-size:10.0pt;font-family:;" "="">s’</span><span style="font-size:10.0pt;font-family:;" "=""> samples (1.95 - 4.01).</span><span style="font-size:10.0pt;font-family:;" "=""> </span><span style="font-size:10.0pt;font-family:;" "="">The nature of doleritic and trachytic magma sources is supported by their展开更多
Magnetic susceptibility data from marine rocks can be used for global correlation due to synchronous variations in global erosion. This work, aims to show that, the magnetic susceptibility signature which exists in th...Magnetic susceptibility data from marine rocks can be used for global correlation due to synchronous variations in global erosion. This work, aims to show that, the magnetic susceptibility signature which exists in the cretaceous sediments of the Babouri-Figuil basin, resides mainly in the detrital constituents. Variations of amplitudes are observed, which can be useful for regional correlation.This amplitude variation results in the transgressive and regressive movements that give way to a fluctuation of detrital deposits because of erosion. Considering the sedimentological study, carried out, different microfacies have been identified in the basin, namely, fluvial facies and lake facies that sometimes contain fossils. The combination of detailed sedimentological analysis and sequence stratigraphy is based on the modeling of vertical and lateral variations within the basin. Finally, the interpretation of the magnetic susceptibility signal suggests that in the detrital domain, this signal is mainly controlled by environmental parameters such as the agitation of the water and the rate of sedimentation, as well as diagenesis.展开更多
The purpose of this work is to characterize the sediments of the Babouri-Figuil<span style="font-family:""><span style="font-family:Verdana;"> Basin from a diagenetic point of view...The purpose of this work is to characterize the sediments of the Babouri-Figuil<span style="font-family:""><span style="font-family:Verdana;"> Basin from a diagenetic point of view, the protolith context and weathering conditions, u</span><span><span style="font-family:Verdana;">sing major element geochemistry and mineralogy of the sedimentary rocks. Microscopic observations of diagenetic phenomena (on and around detrital grains of the basin), and the study of precipitation of the cement show that these sediments have undergone phenomena of compaction, dissolution, recrystallization and cementation. Cementation of quartz by silica is controlled by the rate of precipitation of silica, which is closely related to temperature than pressure. Thus, the sediments of the basin could be influenced by hydrothermalism during diagenesis, which would have inhibited their reservoir quality by generalized cementation phenomena. Geochemical features of the sediments show high contents in SiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> (47.49 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span></span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">90.79 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">), Al</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> (2.92 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">23.18 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">), Fe</sp展开更多
Organic geochemistry methods such as high temperature combustion, Rock-Eval pyrolysis and gas analysis were used to analyze oil shale from Babouri-Figuil Basin. Results show that the average content of organic matter ...Organic geochemistry methods such as high temperature combustion, Rock-Eval pyrolysis and gas analysis were used to analyze oil shale from Babouri-Figuil Basin. Results show that the average content of organic matter is 36.25 %wt, while that of mineral matter is 63.75 %wt. The total organic carbon (TOC) is between 15.93 %wt and 26.82 %wt. The HI vs. Tmax diagram indicates an immature Type I kerogen. The average value of the oil potential (S2b) is 149.95 mg HC/g rock. The gases obtained by retort process are H2, CO2, CO and CnH2n, CnH2n+2. Finally, it emerges that, the organic matter of Babouri-Figuil shales was immature or has just reached the beginning of the oil window. The mineralogical study of Babouri-Figuil oil shale has been carried out by means of XRD (X-Ray Diffractometry) and XRF (X-Ray Fluorescence spectrometry). The results show that mineral matrix contains silica, carbonates, sulphates, oxides and clay minerals. Besides, compounds contain metals and metalloids like Fe, In, Ca. The main oxides are SiO2 (majority), CaO, Fe2O3, Al2O3, SO3, and K2O.展开更多
文摘Magmatism in the Cretaceous sedimentary basins of the Figuil and Léré regions constitutes one of the fundamental parameters in the reconstruction of the history of the Cretaceous sedimentary basins. The main objective of this paper is to constrain the petrogenetic processes of hypovolcanic rocks and to determine their geodynamic context of emplacement. The petrographic study of mafic hypovolcanic and trachytic rocks was carried out under a polarizing microscope on thin sections. For the geochemical study, the major oxides and some trace elements were analyzed by ICP-AES. Trace and rare earth elements were analyzed by ICP-MS. The dolerites of the Cretaceous sedimentary basins are composed of dykes of amphibole bearing dolerites, biotite and pyroxene bearing dolerite, pyroxene bearing dolerites and trachytes. The dykes are in the order of 20 to 100 m wide by several kilometers long and oriented from N23<span style="white-space:normal;"><span style="white-space:normal;"><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span></span></span>E to N90<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>E. The textures of these rocks are sub-ophitic to intergranular for dolerites and trachytic for evolved rocks (trachytes). The geochemical study shows that the dolerites are basaltic in composition with alkaline to subalkaline character. The sampled dykes have an evolution dominated by fractional with the minor impact of the crustal assimilation characterized by low Rb/Y ratios for dolerites (0.36 - 0.97) and high values of Rb/Y for the Pan-African granitoid<span style="font-size:10.0pt;font-family:;" "="">s’</span><span style="font-size:10.0pt;font-family:;" "=""> samples (1.95 - 4.01).</span><span style="font-size:10.0pt;font-family:;" "=""> </span><span style="font-size:10.0pt;font-family:;" "="">The nature of doleritic and trachytic magma sources is supported by their
文摘Magnetic susceptibility data from marine rocks can be used for global correlation due to synchronous variations in global erosion. This work, aims to show that, the magnetic susceptibility signature which exists in the cretaceous sediments of the Babouri-Figuil basin, resides mainly in the detrital constituents. Variations of amplitudes are observed, which can be useful for regional correlation.This amplitude variation results in the transgressive and regressive movements that give way to a fluctuation of detrital deposits because of erosion. Considering the sedimentological study, carried out, different microfacies have been identified in the basin, namely, fluvial facies and lake facies that sometimes contain fossils. The combination of detailed sedimentological analysis and sequence stratigraphy is based on the modeling of vertical and lateral variations within the basin. Finally, the interpretation of the magnetic susceptibility signal suggests that in the detrital domain, this signal is mainly controlled by environmental parameters such as the agitation of the water and the rate of sedimentation, as well as diagenesis.
文摘The purpose of this work is to characterize the sediments of the Babouri-Figuil<span style="font-family:""><span style="font-family:Verdana;"> Basin from a diagenetic point of view, the protolith context and weathering conditions, u</span><span><span style="font-family:Verdana;">sing major element geochemistry and mineralogy of the sedimentary rocks. Microscopic observations of diagenetic phenomena (on and around detrital grains of the basin), and the study of precipitation of the cement show that these sediments have undergone phenomena of compaction, dissolution, recrystallization and cementation. Cementation of quartz by silica is controlled by the rate of precipitation of silica, which is closely related to temperature than pressure. Thus, the sediments of the basin could be influenced by hydrothermalism during diagenesis, which would have inhibited their reservoir quality by generalized cementation phenomena. Geochemical features of the sediments show high contents in SiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> (47.49 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span></span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">90.79 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">), Al</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> (2.92 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">23.18 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">), Fe</sp
基金financial and material supports from the“University Commission for Development”(UCD)and University of Liege-Belgium(ULg).
文摘Organic geochemistry methods such as high temperature combustion, Rock-Eval pyrolysis and gas analysis were used to analyze oil shale from Babouri-Figuil Basin. Results show that the average content of organic matter is 36.25 %wt, while that of mineral matter is 63.75 %wt. The total organic carbon (TOC) is between 15.93 %wt and 26.82 %wt. The HI vs. Tmax diagram indicates an immature Type I kerogen. The average value of the oil potential (S2b) is 149.95 mg HC/g rock. The gases obtained by retort process are H2, CO2, CO and CnH2n, CnH2n+2. Finally, it emerges that, the organic matter of Babouri-Figuil shales was immature or has just reached the beginning of the oil window. The mineralogical study of Babouri-Figuil oil shale has been carried out by means of XRD (X-Ray Diffractometry) and XRF (X-Ray Fluorescence spectrometry). The results show that mineral matrix contains silica, carbonates, sulphates, oxides and clay minerals. Besides, compounds contain metals and metalloids like Fe, In, Ca. The main oxides are SiO2 (majority), CaO, Fe2O3, Al2O3, SO3, and K2O.
