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Key Dolerite Dyke Swarms of Amazonia:U-Pb Constraints on Supercontinent Cycles and Geodynamic Connections with Global LIP Events Through Time
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作者 Wilson TEIXEIRA Mike A.HAMILTON +1 位作者 Vicente A.V.GIRARDI Frederico M.FALEIROS 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期84-85,共2页
High-resolution U–Pb(ID-TIMS,baddeleyite)ages are presented for mafic dykes from selected swarms in two important Amazonian regions:the Carajás Province in the east,and the Rio Apa block in the southwest–areas
关键词 Pb U-Pb Constraints on Supercontinent Cycles and Geodynamic Connections with Global LIP Events Through Time Key dolerite dyke Swarms of Amazonia LIP
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Tectonic Style Associated with the Doleritic Dykes of the Téra-Ayorou Pluton (Liptako, Western Niger)
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作者 Kamayé Tourba Gambo Ranaou Noura +5 位作者 Abdou Dodo Bohari Karimou Dia Hantchi Mallam Mamane Hallarou Hassane Ibrahim Maharou Yacouba Ahmed Moussa Konaté 《International Journal of Geosciences》 CAS 2024年第8期567-581,共15页
The doleritic dykes present in the Téra-Ayorou pluton crosscut the basement of the Nigerien Liptako and are part of the system of intrusive mafic dykes in the Paleoproterozoic domain of the Léo-Man ridge. In... The doleritic dykes present in the Téra-Ayorou pluton crosscut the basement of the Nigerien Liptako and are part of the system of intrusive mafic dykes in the Paleoproterozoic domain of the Léo-Man ridge. In the previous work, emphasis was placed on the petrology, geochemistry and geochronology of the Liptako doleritic dykes. This study aims to analyze the tectonic style of intrusive doleritic dykes in the Téra-Ayorou pluton. The characterization of the deformation which affected the doleritic dykes of the Téra-Ayorou pluton is important for the evaluation of their economic potential. To this end, measurements of tectonic structure planes were taken in the field, and samples were taken from the chilled margin and cores of dolerite dykes, before being processed in the laboratory. Analysis of the tectonic structures collected revealed a brittle tectonic pattern, characterizing a phase of deformation subdivided into two episodes D1 and D2. Episode D1, with its subvertically dipping normal faults and simple N70˚ - N110˚ fractures, is compatible with N-S extension. On the other hand, episode D2, which created shear corridors by reactivation of pre-existing fractures and oriented N150˚ - N170˚, is associated with a WSW-ENE extension. These results open up prospects for the exploration of gold, uranium mineralization and diamonds in the north-west of Niger. 展开更多
关键词 dolerite dykes Associated Structures Deformation Phases North Liptako NIGER
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Petrography and Geochemical Characterization of Dolerites from Figuil (Northern Cameroon) and Léré(Southwestern Chad) 被引量:2
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作者 Moussa Ngarena Klamadji Merlin Gountié Dedzo +1 位作者 Rigobert Tchameni Daouda Dawaï 《International Journal of Geosciences》 2020年第7期459-482,共24页
This work presents the petrographic and geochemical data of the dolerite <span>dykes crosscutting the Pan-African basement of Figuil (North-Cameroon) and </span>Léré (South-West Chad) in order to... This work presents the petrographic and geochemical data of the dolerite <span>dykes crosscutting the Pan-African basement of Figuil (North-Cameroon) and </span>Léré (South-West Chad) in order to approach their petrogenesis and their emplacement context. Two groups of dolerites have been highlighted by petrograph<span>ic and geochemical studies. These groups were discrimin</span>ated by their TiO<sub>2</sub>, Fe<sub>2</sub>O<sub>3</sub>, REE, Ba, Nb, Zr, La and Hf contents which are relatively higher in group I;group II, on the other hand, has higher MgO, Mg#, Sc, Ni and Cr contents. The mineralogical assemblage of these dolerites is made up by plagioclases, pyroxenes, olivine, oxides, amphibole, biotite and sometimes pyrite, calcite, apatite, epidote and chlorite. The behaviour of the major and trace elements suggest that studied dolerites have an evolution dominated by fractional crystallization. Most dolerite samples show higher REE concentrations and (La/Yb)<sub>N</sub> > 8.7, (Tb/Yb)<sub>N</sub> > 1.9 and Dy/Yb > 2 ratios characterizing a garnet-bearing mantle. The difference in incompatible elements between the two groups is explained by the degree of partial melting of the same source which becomes more important over time. Low (Ce/Yb)<sub>N</sub> values (3.3 - 11.58) <span>also suggest relatively low partial melting degree of the source. Fractional crystalli</span>zation process was possibly combined with minor crustal contamination as shown by enrichment of Th/Yb from group II to Group I that might be due to turbulent magma emplacement. The chemical compositions of these dolerites are similar to that of continental tholeiites with slightly moderate nega<span>tive Nb-Ta anomalies which are attributed to crustal contamination of magma</span>s. As other dolerites of Cameroon, continental tholeiitic signature of the studied dolerites is evidenced in geotectonic discrimination diagrams with Group II dolerite compositions falling within the field of tholeiitic basalts and group I within the field of alkali basalts. 展开更多
关键词 Doleritic dykes Pan-African Basement Continental Tholeiites North-Cameroon South-West of Chad
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Aeromagnetic Imagery as a Tool to Help Identify the Structures Controlling the Emplacement of the Kenieba Kimberlite Pipes (Western Mali, West African Craton)
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作者 Baco Traore Gbele Ouattara +4 位作者 Marc Ephrem Allialy Ousmane Wane Mohamed Moustapha Ndam Njikam Adama Youssouf Kone Souleymane Sangare 《Open Journal of Geology》 2023年第11期1177-1194,共18页
A kimberlite field, represented by fertile and sterile kimberlite pipes (chimneys) is located in the region of Kenieba (West Mali, Kédougou-Kenieba inlier, West African Craton). Thirty pipes and kimberlite dykes ... A kimberlite field, represented by fertile and sterile kimberlite pipes (chimneys) is located in the region of Kenieba (West Mali, Kédougou-Kenieba inlier, West African Craton). Thirty pipes and kimberlite dykes have been identified in the birimian formations, composed mainly of metasediments and granitoids, covered by sedimentary formations (sandstones and conglomerates) of Neoproterozoic age. All these formations are injected with dykes and doleritic sills of Jurassic age. The study of kimberlite pipes is still stammering in Mali, and thus no previous study has allowed to characterize the structures controlling their implementation. The reinterpretation of aeromagnetic data validated by field work indicates that the major structures of the Kenieba region are oriented NNE-SSW, NE-SW, E-W and NW-SE. These structures (faults and kimberlite pipes) are often associated with dolerite dykes, which would imply an injection of dolerite magma into the other formations. The location of the known kimberlite pipes makes it possible to say that the direction NW-SE is the most favorable for the exploration of kimberlites in the region of Kenieba. 展开更多
关键词 Kimberlite Pipes Doleritic dykes Fractures Aeromagnetism Kenieba MALI
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