Bureau De Recherches Geologiques Et Minieres Research Articles

Discussion of the paper by Yahya et al. 2018 entitled “Paleoenvironmental and paleoclimatic conditions during the deposition of the bauxite layer (Upper Cretaceous) using multi-proxy geochemical and palynological analyses, in the Zabirah Area, Northern Saudi Arabia” (Arabian Journal of Geosciences v.11, Article No.15)

Yahya et al. (2018) interpreted the palaeoenvironmental and palaeoclimatic conditions prevalent during the formation of the Late Cretaceous Az Zabirah Bauxite in Northern Saudi Arabia. They suggest that claystones associated with the bauxite profile are of Maastrichtian age based on palynology. This age interpretation is counter to the evidence of decades of detailed mapping and biostratigraphic analyses conducted by specialists from the Bureau de Recherches Geologiques et Minieres (BRGM) that demonstrate an Albian to Cenomanian age for the Az Zabirah Bauxite. This older age is even reported in Yahya et al.’s text quoting BRGM and Arabian American Oil Company palynology reports yet, for reasons that remain obscure, was rejected in favour of an unsubstantiated Maastrichtian age. More recent publications on the Cretaceous stratigraphy of Saudi Arabia were not cited. Furthermore, the palynology presented in the paper does not confirm their age interpretation. A second bauxite horizon, the “Pre-Aruma Bauxite” is present nearby but all descriptions and illustrations in the paper suggest that this is not the studied horizon. Moreover, recent Sr isotope dating suggests that the “Pre-Aruma Bauxite” is older than Middle Campanian. The value of sedimentological, palaeoclimatic and palaeoenvironmental interpretations requires them to be placed in their correct stratigraphic context. The authors have singularly failed to achieve this in their publication.

Zdeněk Johan (1935–2016)

Zdeněk Johan, emeritus Scientific Director of Bureau de Recherches Geologiques et Minieres (BRGM), passed away in Orleans (France) on February 13, 2016. Zdeněk Johan was born on November 18, 1935 in Lomnice nad Popelkou in the north of the Czech Republic (formerly Czechoslovakia). During his youth he divided his time between his three major interests: collecting minerals, astronomy, and classical music (he was an excellent pianist and singer). He finally decided to study mineralogy at Charles University in Prague, where he graduated with honours in 1958. In 1961 he defended his PhD thesis on the mineralogy of the binary Cu–As system. He was persecuted by the communist regime, and decided to emigrate in France in 1969. He worked as a research officer in BRGM, as did his wife Věra, where he later became Head of the Department of Mineralogy. Between 1977 and 1989 he was a Director of the Centre de Recherches sur la Synthese et la Chimie des Mineraux of the Centre National …

A tribute to Philippe Rossi

Publication of this special volume of the Bulletin de la Societe geologique de France, dedicated to the evolution of the southern segment of the European Variscan chain, is an opportunity for the French community of Geosciences to pay a friendly honoring tribute to Philippe Rossi, a tireless promoter of geology within the important institution that is the Bureau de Recherches Geologiques et Minieres (BRGM). After his secondary studies at the Lycee J.B. Corot in Savigny-sur-Orge, Philippe Rossi discovered geology at the Universite Paris-Sud (Orsay), where he defended in 1975 a Doctorat thesis entitled: “ Geologie et gitologie du Cerro San Cristobal Logrosan, Caceres, Espagne”. In the wake of his thesis, Philippe joined the BRGM where he went, from the 1980s, to play a prominent role as both a geologist specialist of the Variscan chain in Europe, and a key player of the evolution and accomplishment of the French mapping program (Programme de la Carte Geologique de la France). First of all, Philippe is recognized in our community as a researcher enthusiast about the petrologic and geodynamic evolution of the European Variscan chain. In 1986, he defended a Doctorat d’Etat thesis at the Universite P. Sabatier (Toulouse) entitled: “ Organisation et genese d’un grand batholite orogenique : le batholite calco-alcalin de la Corse ”. In parallel, Philippe has led the cartographic synthesis of Corsica at 1/250 000 published in 1980, and was involved in the survey of 7 geological maps at 1/50 000 in Corsica, to be published between 1984 and 2012. In 2009, he and his colleagues published a remarkable synthesis of the Corso-Sardinian segment of the Variscan chain, updated in 2014 with regard to the place of Corsica in the Variscan “puzzle”. This work conducted in collaboration with A. Cocherie within the BRGM, but also with many French and …

Tectonic evolution of the Oman Mountains: an introduction

It is now more than 20 years since the GeologicalSociety published The Geology and Tectonics ofthe Oman Region (Robertson et al. 1990) as oneof its early special publications. That volume, the‘blue book’ as it became fondly known to multiplegenerations of undergraduates, has been a majorreference on the geology of Oman for many whowork in the region. This present volume, moremodest in its size compared to its illustrious prede-cessor, is the fruit of a conference on The Geologyof the Arabian Plate and the Oman Mountainsheld in January 2012 at Sultan Qaboos Universityin Muscat, organized by Professor Sobhi Nasirwith colleagues from Sultan Qaboos University,the Oman Government and the Geological Societyof Oman. Since the first comprehensive study ofthe geology of the Oman Mountains during thelate 1960s and early 1970s by Ken Glennie and histeam from Shell, the Oman Mountains have beenknown to contain some of the most spectacularand best-exposed geology not only in the MiddleEast but across the world. A summary of the geo-logy and the lithostratigraphy is given in Figure 1.The publications of Glennie et al. (1973, 1974),building on many earlier Shell geologists’ internalreports (notably D. M. Morton, R. H. Tschopp,H. H. Wilson, B. M. Reinhardt and M. W. Hughes-Clarke) set out the major stratigraphic frameworkfor the whole area, defined the major structuresand critically interpreted the Semail Ophiolite as athrust sheet of oceanic crust and upper mantleemplaced onto the previously passive continentalmargin of Arabia. Since the Glennie et al. (1974)memoir was published, oil companies have carriedout increasingly more intensive work comparingwell sections in the interior with the Permian–Mesozoic shelf carbonates so beautifully exposedalong numerous wadis cutting through the JebelAl-Akhdar and Saih Hatat massifs.During the late 1970s and 1980s two majorresearchteamsfromtheUSGS(ledbyBobColemanand Cliff Hopson) and the Open University, UK(led by Ian Gass, John Smewing and Steve Lip-pard) conducted detailed geological surveys acrossthe ophiolite in the Muscat–Ibra transect (USGS)and northern ophiolite (OU), respectively. Theirresults were published in a Special Issue of theJournal of Geophysical Research (volume 86,editors Coleman & Hopson 1981) and the Geologi-cal Society of London Memoir no. 11 (Lippard etal.1986). Major systematic mapping of the OmanMountains as well as the interior, Batain coast andDhofar region has been carried out by the Bureaude Recherches Ge´ologiques et Minieres (BRGM),France, the Geological Survey of Japan and theUniversity of Berne, Switzerland (see for examplePeters et al. (1991)) and the whole UAE part of thenorthern Oman Mountains was recently mapped bythe British Geological Survey (UAE Ministry ofEnergy Petroleum & Mineral Resources 2012).During the last 20 years major research groupsfrom France, Japan, USA and the UK have con-ducted research projects in the country. Detailedfield studies of the Oman Ophiolite have beencombined with geochemical and isotopic studiesto determine the tectonic setting and evolution ofthe Late Cretaceous oceanic crust and upper mantle(Boudier & Juteau 2000). Field-based studies havealso been linked to ocean drilling sites, in particularthe East Pacific rise, to compare the ophiolite toregions of active fast spreading. Key to the obduc-tion–emplacement story are the amphibolite andgreenschist facies rocks in the metamorphic solethat record an inverted metamorphic field gradientalong the base of the ophiolite. The ophiolite hasbeen the source of recent detailed studies involvingthe possible sequestration of CO

Caracterização e avaliação de reservas geológicas do depósito mineral de Farim-Saliquinhé

Esse trabalho apresenta uma metodologia integrada e os principais resultados da modelagem geológica e econômica do jazigo mineral de fosfato de Farim-Saliquinhé, Guiné-Bissau. Esse jazigo foi, primeiramente, reconhecido nos anos 80, pelo Bureau de Recherches Géologiques et Minières (BRGM), como sendo de origem sedimentar. A caracterização morfológica consistiu na estimação da profundidade e da espessura da camada de estéril e das formações mineralizadas (rochas fosfáticas FPA, principais, e carbonato-fosfática FPB, secundária). A caracterização dos teores em P2O5 foi efetuada para uma malha de blocos por krigagem e, posteriormente, por simulação, para caracterizar a incerteza e classificar as reservas em inferidas, indicadas ou medidas. A morfologia e os teores foram, posteriormente, convertidos em benefícios/custos, conforme um potencial cenário de exploração mineral. No que se refere à modelagem econômica, apresenta-se um estudo de pré-viabilidade econômica, com análise de sensibilidade, relativamente aos parâmetros preço de venda, custo de extração, custo de transporte e desconto no preço de venda da rocha fosfática por não concentração e uma estimativa da taxa interna de retorno (TIR) do projecto para um cenário-base e uma variante.

CDSA: A New Seismological Data Center for the French Lesser Antilles

The Lesser Antilles, in the eastern Caribbean, is prone to a large seismic hazard due to the subduction of the Atlantic lithosphere beneath the Caribbean plate, with a slow convergence rate of 2 cm/yr (Demets et al. 2000; Mann et al. 2002). The largest historical earthquake in the region, in 1843 between Guadeloupe and Antigua, had a magnitude estimate of 7.5 to 8 (Bernard and Lambert 1988), but historical seismicity covers too short a period of time (less than three and one-half centuries) to estimate the recurrence time of strong events or their plausible maximum magnitude. The latest destructive earthquake, Les Saintes in Guadeloupe in 2004, had a magnitude 6.3 (Institut de Physique du Globe de Paris 2004; Bertil et al. 2004). To better understand the regional geodynamics and assess the related seismic hazard, we must improve our knowledge and our understanding of the area's present seismicity. Since the 1950s, several regional research institutes have monitored local seismicity. The Institut de Physique du Globe de Paris (IPGP) and Bureau de Recherches Geologiques et Minieres (BRGM) have set up various seismological and accelerometric arrays to monitor the French islands of Guadeloupe and Martinique. As a consequence, several large datasets with very different formats and time spans exist, scattered among several sites. Providing a more integrated database for the seismicity of the Lesser Antilles arc was the primary motivation for creating the French Antilles Seismological Data Base (Centre de Donnees Sismologiques des Antilles, CDSA). The aim of this paper is to introduce the newly created CDSA and to illustrate its capacity for improving our knowledge of the region's seismicity. In the first part of this study, we present the various arrays, waveform databases, and seismicity catalogs used by the CDSA. In the second part, we present and discuss new …

First Permian Ostracode Fauna from the Arabian Plate (Khuff Formation, Sultanate of Oman)

First Permian Ostracode Fauna from the Arabian Plate (Khuff Formation, Sultanate of Oman)

Symposium on ophiolite genesis and evolution of oceanic lithosphere

The recently published Special Publication No 49 of the Geological Society of London The Geology and Tectorlics of the Oman Region edited by A. H. F. Robertson, M. P. Searle and A. C. Ries (Feb. 1990) resulted largely from a six year AMOCO-funded project concentrating mainly on the structure, strat atigraphy and sedimentology of the platform margin and basin sediments beneath the Semail ophiolite. This study, and more particularly the BRGM-French project (1982–1990) formed the basis of the ophiolite conference. It was held at the Sultan Qaboos University, Sultanate of Oman, 7–18 January 1990, and was the first, major, international geological conference to be held in Oman. Over 300participants from 27 countries attended. Since the classic work of Glennie et al. (1974) and the Shell team, the Semail ophiolite in the Oman Mountains has been widely regarded as the largest, best exposed and most spectacular example of an obducted ophiolite complex anywhere in the world. Subsequent field projects, including the Open University Oman Ophiolite project (1975–1985) summarized by Lippard et al. (1986) and the University of California-USGS project (1977–1979) published in a special issue of Journal of Geophysical Research (1981) vol. 86 , concentrated mainly on the Semail ophiolite complex. Since 1982, the Bureau de Recherches Geologiques et Minieres (BRGM) have remapped large areas of the central and southern mountains and 13 maps at 1: 100,OOO scale have been published. Together with new detailed studies of the Semail ophiolite, some of the French teams’ results have been published in a

Geological data bases combine

In a move designed to eliminate overlap and increase coverage of scholarly publications, three major institutions have agreed to pool their resources in compiling a common geological bibliographic data base. The American Geological Institute (AGI), the Bureau de Recherches Geologiques et Minieres (BRGM), and the Centre National de la Recherche Scientifique (CNRS) will begin producing a joint bibliographic record in 1981, according to information furnished by AGI.The associations will retain their present reference resources—AGI's GeoRef, BRGM's Geode, and the geology sections of CNRS's Pascal—but each will contain all citations in the joint data base. French and English will be the primary languages. Coverage will include all materials previous indexed by the individual reference services.