检索结果-南通市图书馆

Journal of Geoscience and Environment Protection 2024年第1期12卷 180-210页

作者： Bah-Yero Liman Ngounouno Ismaïla Mbowou Gbambié Isaac Bertrand Alpha Baster Kenfack Fokem André William Boroh amadou diguim kepnamou Department of Earth Sciences Faculty of Science University of Ngaoundéré Ngaoundéré Cameroon Department of Mining Geology School of Geology and Mining and Engineering University of Ngaoundéré Meiganga Cameroon Department of Earth Sciences Faculty of Science University of Garoua Garoua Cameroon

The aim of this study of the spatial dispersion of tin, niobium and tantalum mineralization associated with the Mayo Darlé granitoids was to produce prospecting guides through predictive maps of Sn, Nb and Ta in the region. It was based on a database (in appendix) obtained after analysis of rock samples (greisens and quartz veins) collected in the field, using a portable X-ray fluorescence (XRF) spectrometer. Two approaches were used: 1) structural studies in the field using the directions of veins and fractures 2) the use of variographic maps, an essential element in geostatistics for determining directional anisotropies. A joint synthesis of the modelling results shows that tin, tantalum and niobium mineralization at Mayo Darlé is concentrated along strike intervals N315E to N320E, with mineralization also occurring along strike N35E for high-grade Sn, medium-grade Ta and low-grade Nb. In short, mineral concentrations disperse progressively in space: positively from east to west for tantalum and niobium, and inversely for tin.

关键词： Mayo Darlé Tin Niobium Tantalum Geostatistics Mapping

Peraluminous granitoids within the Hangloa area,Adamawa-YadéDomain,Cameroon:Petrogenesis and tectonic implication

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geochimica 2022年第6期41卷 1104-1122页

作者： Yaya Fodoué Mero Yannah Rigobert Tchameni Wadjou Jacques Wassouo amadou diguim kepnamou Joseph Penaye Abakar Mahamat Emmnuel Nomo Negue Institute of Geology and Mining Research P.O Box 4110NlongkakYaoundeCameroon Department of Earth Sciences Faculty of ScienceUniversity of NgaoundereP.O.Box 454NgaoundereCameroon Department of Earth Science University of Yaounde IYaoundeCameroon

Hangloa granitoids form part of the wide range calc-alkaline Pan-African granitic suites within the Adamawa Yade Domain(AYD)in *** are several reports on metaluminous granitoids within this *** peraluminous suite has been locally reported and their petrogenesis is not fully *** and whole-rock geochemistry were used to study the petrogenesis/formation of granitic rocks within this *** results show that the granitoids are composed of quartzo-feldspathic,made up of granites,monzonites and quartz monzonites which were intruded in the Paleoproterozoic orthogneissic *** major and trace element compositions show that they are high-K calc-alkaline to shoshonites,with S-type *** molar ratio A/CNK is>1.1,while the ratio of CaO+Na_(2)O/Al_(2)O_(3) is generally<1 making them strongly *** REE shows enrichment in the LREE over the HREE,with(La/Yb)N varying from 11.9 to 53.32,(Dy/Yb)N from 0.77 to 2.13 and moderately negative Eu anomaly((Eu/Eu^(*))N range from 0.42 to 0.93).Most granite samples show depletion in P,with CaO/Na_(2)O<0.3 and Rb/Sr≤1 indicative of clay-poor metapelitic source,while the others show clay-rich metagreywackes *** strong peraluminosity,S-type affinity,high Ba/Sr,Ba/Rb and low Rb/Sr indicate they are *** compositional variation might be induced by the partial melting of different source materials followed by fractional crystallization of the granitic *** source nature requires fragments of Paleoproterozoic metasedimentary and metaigneous rocks derived from the collision between the north-central Cameroon block and the Congo Craton during the Pan-African.

关键词： Petrography Geochemistry Peraluminous Hangloa Adamawa-Yade-Domain

Petrography and Geochemistry of Precambrian Basement Straddling the Cameroon-Chad Border:The Touboro Baibokoum Area

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

International Journal of Geosciences 2014年第4期5卷 418-431页

作者： Naimou Seguem Ganwa Alembert Alexandre Urs Klotzli amadou diguim kepnamou Ekodeck Georges Emmanuel Department of Geology Faculty of Sciences and TechniquesUniversity Adam Barka of AbecheAbecheChad Department of Earth Sciences Faculty of SciencesUniversity of NgaoundereNgaoundereCameroon Labor für Geochronologie Department für LithospharenforschungUniversitat WienWienAustria Department of Earth Sciences Faculty of SciencesUniversity of Yaounde IYaoundeCameroon

The border of Cameroon and Chad is characterized by a Precambrian basement straddling the Touboro-Ba?bokoum area;this basement is made up of gneiss, amphibolite and granitoids (granite, syenite, granodiorite). The studied rocks display high-K calk-alcalcaline to shoshonitic characteristic. Granitoids are metaluminous. Rocks under study derived from partial melts from metabasaltic to metatonalitic sources, and partial melts from metagreywackes. They shear the same origin as many granitoids describe westward in the Meiganga area and west Cameroon. This shows that the basement straddling the Touboro-Ba?bokoum area belongs to the Adamawa-Yadé Domain of the Central African Fold Belt.

关键词： Precambrian Basement Touboro-Baibokoum Cameroon Chad Adamawa-Yade Domain Central African Fold Beld

Petrography and Geochemistry of Baïbokoum-Touboro-Ngaoundaye Granitoids on the Chad-Cameroon-RCA Borders (Adamawa-Yade Domain)

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Geology 2022年第2期12卷 136-155页

作者： Naïmou Seguem Mbaguedjé Diondoh amadou diguim kepnamou Ntoumbé Mama Mabrouk Sami Ganwa Alembert Alexandre Ekodeck Georges Emmanuel Department of Geology Faculty of Sciences and Techniques University Adam Barka of Abeche Abeche Chad Department of Mines and Geology School of Geology and Mining Engineering University of Ngaoundere Meiganga Cameroon Department of Geology Faculty of Sciences Minia University El-Minia Egypt Department of Earth Sciences Faculty of Sciences University of Ngaoundere Ngaoundere Cameroon Department of Earth Sciences Faculty of Sciences University of Yaounde I Yaounde Cameroon

The Baïbokoum-Touboro-Ngaoundaye area is located in the Adamoua-Yade domain of the Pan-African Fold Belt in Central Africa. The present work concerns the petrographic and geochemical study. The study area is made up of plutonic rocks including two amphibole granites, four biotite and muscovite granites, two syenites and one monzonite sample. These rocks have a granular porphyroid texture, with a mylonitic tendency. The primary paragenesis consists of Opx + Cpx + Amp + Bt + Pl + Or + Mic + Qtz + Ap + Sph + Zr and the secondary paragenesis consisting of Ch + Op. Plutonic rocks are shoshonitic to calc-alkaline with a strong potassic affinity. The REE profiles of these rocks show a negative anomaly of Eu in the granites and no Eu anomaly in syenites and monzonite (syeno-diorite). Multielement spectra of plutonic rocks present a negative anomaly in Nb-Ta and Ti. Fractional crystallization is the process that made these rocks of study area. These rocks are placed in a subduction to syn-collisional (VAG + Syn-COLG) and of intraplate granitoids (WPG) environment.

关键词： Petrography Geochemistry Baïbokoum-Touboro-Ngaoundaye Adamawa-Yade Domain Pan-African Fold Belt

Petrological and Geochemical Studies on the Si-Undersaturated Rocks of the Mount Cameroon: Genesis of the Camptonite and Nephelinite at the Cameroon Hot Line

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Geology 2021年第6期11卷 239-252页

作者： Ntoumbé Mama Amaya Adama diguim kepnamou amadou Mbowou Gambie Isaac Bertrand Naimou Seguem Ngounouno Ismaïla Department of Mines Geology School of Geology and Mining Engineering University of Ngaoundere Meiganga Cameroon Department of Geomatic and Geology Mapping School of Geology and Mining Engineering University of Ngaoundere Meiganga Cameroon Department of Geology Faculty of Sciences and Techniques University Adam Barka of Abeche Abeche Chad

The Cameroon hot line is dominated by magmatic rocks. The variations of magma and chemistry are generally due to the difference of physical conditions and chemistry in the magma source region during the ascent of magma. The Mt Etinde and the Mt Cameroon, both edifices belong to the Cameroon Hot line, have a particularity some rare rocks such as camptonite and nephelinite. The relationship between the silica undersaturated rocks in the both edifices is characterized by the lateral variation appear through the petrography of the different rocks. The concerned geochemical data allow to compare the Mount Etinde nephelinite and Mount Cameroon camptonite where the differentiation process reflects geochemical affinities from a basaltic magma source on the Cameroon hot line. The compatible elements between the Mount Etinde nephelinite and the Mount Cameroon camptonite and basalt correlate with the difference in modal compositions of mineral phases. The lateral variation of major and trace element contents in the Mount Cameroon camptonite and Mount Etinde nephelinite seem to be related to the difference in the fractional crystallization processes of mineral phases, the difference in the partial melting processes and the metasomatism source rich in volatile. The silica-undersaturated character of the camptonite and nephelinite could be attributed to assimilation of carbonate rocks within depth-level magma chambers. Trace element AFC modelling revealed that the parental magmas of both edifice volcanic rocks were mostly affected by fractional crystallisation coupled with metasomatism process in Ca rich source.

关键词： Nephelinite Camptonite Link Source Cameroon Hot Line