The oldest rock of Ivory Coast

Kouamelan, Alain Nicaise; Djro, Sagbrou Chérubin; Allialy, Marc Ephrem; Paquette, Jean‐Louis; Peucat, Jean-Jacques

doi:10.1016/j.jafrearsci.2014.12.004

Cited by 27 publications

(18 citation statements)

References 32 publications

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“…The age of the formations is not exactly known, and diverse estimates have been proposed in different studies (e.g. Kouamelan et al, 2015;Lompo, 2010;Feybesse et al, 2006;Egal et al, 2002;Guiraud, 1988). However, this shield can be subdivided into two domains:…”

Section: From Regional To Local Geologymentioning

confidence: 99%

Geophysical demonstration of the absence of correlation between lineaments and hydrogeologically usefull fractures: Case study of the Sanon hard rock aquifer (central northern Burkina Faso)

Soro

Koïta

Biaou

et al. 2017

Journal of African Earth Sciences

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The conceptualization of hard rock aquifers in terms of their geometry and structure has undergone considerable progress over the last two decades. Despite these advances, hydrogeologists are still divided by the models used to describe two central concepts: (i) the influence of weathering processes on hydraulic conductivity; (ii) the influence of tectonics on the hydraulic conductivity of hard rock aquifers. In order to provide further insight into this debate, the present study proposes a conceptual model for hard rock aquifers, based on an integrated hydrogeological and geophysical approach, using information acquired at different scales. The data and observations used for this case study were derived from the Sanon experimental site, located in Burkina Faso, which is presently exposed to a Sudano-Sahelian climate. The methodological approach consisted firstly in developing a description of the site's weathering profile at the scale of a borehole, based on lithologs and electrical resistivity logs. In a second step, the site's ridge to ridge (longitudinal) weathering profile was established from several 2D resistivity sections crossing a maximum number of lineament structures, which in some prior studies were considered to be the superficial manifestation of tectonic fractures. The results show that at that scale the weathering profile is comprised of three main layers, which from top to bottom are referred to as: the saprolite, the fissured layer and the fresh rock. This weathering profile model is consistent with other models proposed in recent years, suggesting that the hydraulic conductivity of hard rock aquifers is a consequence of weathering processes, rather than tectonic fracturing. Tectonic fractures are not visible on the 2D sections of the ridge to ridge profiles, and the lineaments originally thought to be overground representations of tectonic fractures are likely to have different origins. The lack of a substantial correlation between tectonic lineaments and fractures appears to account for the high incidence of negative boreholes in hard rock aquifers, where the siting of drillings has systematically been 3 based on lineament studies and on geophysical studies looking for vertical fractures such as profiling and vertical electrical sounding. There is thus a need to revise current hydrogeological concepts and methodologies to site wells based on tectonic fractures represented by lineaments.

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Section: From Regional To Local Geologymentioning

confidence: 99%

Geophysical demonstration of the absence of correlation between lineaments and hydrogeologically usefull fractures: Case study of the Sanon hard rock aquifer (central northern Burkina Faso)

Soro

Koïta

Biaou

et al. 2017

Journal of African Earth Sciences

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“…At the petrological level, grey gneisses are a typical Archean lithology, of which TTG orthogneiss suites are a common component that has been the focus of extensive research (Moorbath et al, 1972;Moorbath, 1975;Savanier et al, 2003;Martin et al, 2014, Koffi et al, 2020. Whereas in the SASCA domain, we observe lithologies mainly composed of metasediments (paragneiss, micaschists), grey gneiss (Kouamelan, 1996;Kouamelan et al, 2015;Kouadio, 2017), all intruded by granitoids as well as dolerite or metabasite dykes (Papon, 1973;Kouadio, 2017). Mafic dykes swarms may simultaneously provide information on the geodynamic setting, geochemical characteristics of their mantle source areas, age distribution and paleomagnetic-determined positions (paleolatitude and paleo-orientations) at the time of their formation (Ernst, 2014).…”

Section: Introductionmentioning

confidence: 66%

“…Paleoproterozoic domains lie adjacent to the Archean domain ( Figure 1) and are characterized by the typical Archean-like greenstone-granitoid assemblages that principally consist of volcanic, volcano-sedimentary, and sedimentary sequences separated either by extensive TTG and granite provinces or by slightly younger but still Paleoproterozoic sedimentary basins. The Archean and Paleoproterozoic domains were affected by multiple tectono-metamorphic and magmatic events, referred to as Leonian (3.2-3.0 Ga); Liberian (2.9-2.7 Ga) and Eburnean (2.15-2.07 Ga) orogenies, (Liégeois et al, 1991, Christian et al, 2004Thiéblemont, 2005;Gouédji et al, 2014;Kouamelan et al, 2015;Koffi et al, 2020). In particular, the whole complex of volcanic, volcano-sedimentary and sedimentary units has been intruded by several generations of granitoids (Thiéblemont, 2005…”

Section: Geological Contextmentioning

confidence: 99%

Petrographic and Geochemical Characteristics of the Metabasites of the SASCA Domain (Yonaké, Mani- Béréby and Dehié Sectors), South-West Côte d'Ivoire

Hervé

Nestor

Ephrem

et al. 2020

ESJ

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The petrographic and geochemical study of six (6) metabasites located in the Archean-Paleoproterozoic transition domain (SASCA domain, SouthWest Côte d'Ivoire) identified dolerites and gabbros. The thin sections revealed two textures: the doleritic texture (dolerite) and the granoblastic texture (gabbro). The dolerites are composed of plagioclase wands, pyroxene and olivine. Gabbros have a composition of pyroxene (clinopyroxene), green hornblende, plagioclase, biotite and rare quartz. Geochemical analysis, especially the major elements, corroborated the gabbroic character of the metabasites. Trace elements and rare earths helped to constrain the origin of the metabasites by showing: (i) their belonging to a tholeiitic series, (ii) a mantle source contaminated by the continental crust, and (iii) their emplacement in the field of intraplate or volcanic arc basalts.

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“…The study of major and trace elements provides information about rocks and minerals formation conditions. Authors [17] [34] [35] [36] have studied rocks similar to those of this study and none of them reveal anomalies likely to modify the geochemical characters. Thus, we use the major and trace elements to highlight the petro-geochemical characteristics of the Alahina meta-sediments.…”

Section: Nature and Provenance Of Metasedimentsmentioning

confidence: 99%

Metasediments in the Alahina Sector and Associated Mineralization (North-Eastern Guinea)

Tchokpon¹,

Kaki²,

Adissin³

et al. 2019

OJG

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The Alahina sector is located in the NorthEast of Guinea, precisely in the Siguiri volcano-sedimentary basin. It consists mainly of meta-sediments traversed by Paleoproterozoic pyroclastite, granite, monzogranite and granodiorite veins as well as Mesozoic dolerite and gabbros veins. This article presents new data, on the one hand, on the geochemical petrographic features and the origin of the metasediments of this zone, and on the other hand, on the genetic model of the gold mineralization that they contain. Field observations, as well as petrographic and geochemical studies reveal that the meta-sediments consist of sericite and chlorite schists. They belong to the groups of shales and grauwackes. Their protholites are moderately altered (60 < CIA < 80) andesitic, basaltic and granodioritic rocks emplaced in a geotectonic oceanic island arc and/or active continental margin. Their chondrite normalized REE patterns show a moderate LREE enrichment (La N /Yb N = 6.31-13.24) and a flat heavy rare earth patterns (HREE). This spectrum is almost identical to those of the "Post-Archean average Australian Shale" and Early Proterozoic Greywackes. Two types of polyphase gold mineralization occur in the Alahina sector: disseminated and veined. They consist of particular of grains and nanoparticles pyrite associated with gold, magnetite, hematite, ilmenite. The hydrothermal alteration accompanying this mineralization consists of silica, microcline, chlorite-epidote-sericite-carbonates.

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The oldest rock of Ivory Coast

Cited by 27 publications

References 32 publications

Geophysical demonstration of the absence of correlation between lineaments and hydrogeologically usefull fractures: Case study of the Sanon hard rock aquifer (central northern Burkina Faso)

Geophysical demonstration of the absence of correlation between lineaments and hydrogeologically usefull fractures: Case study of the Sanon hard rock aquifer (central northern Burkina Faso)

Petrographic and Geochemical Characteristics of the Metabasites of the SASCA Domain (Yonaké, Mani- Béréby and Dehié Sectors), South-West Côte d'Ivoire

Metasediments in the Alahina Sector and Associated Mineralization (North-Eastern Guinea)

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