Éditeur(s) : Gauthier-Villars
Résumé : The dissolved Mn distribution on an oceanographic section along 50-degrees-W in the western North Atlantic shows decreasing concentrations in the offshore direction in the surface layer and with depth at the deep water stations. Leachable particulate Mn concentrations are low in the open ocean surface waters and elevated at intermediate depths. Dissolved Al concentrations in the surface layer are higher in the open ocean than on the shelf and the vertical distributions are characterized by surface maxima, a subsurface minimum at almost-equal-to 1 000 m and increasing concentrations in the deep waters. Leachable particulate Al concentrations are elevated on the shelf and in open ocean surface waters compared to the intermediate and deep waters. The Deep Western Boundary Current has high levels of dissolved Al and leachable particulate Mn and Al, and low levels of dissolved Mn. The distribution of dissolved Al is controlled primarily by inputs from atmospheric dust and removal onto biogenic particles. Both fluvial and atmospheric inputs affect dissolved Mn levels with removal occurring primarily by oxidation of Mn2+. The Al distribution is characterized by short residence times in shelf and surface waters and relatively constant distribution coefficients. The Mn distribution is characterized by longer surface water residence times, shorter deep water residence times, and more widely varying distribution coefficients than Al. Removal of Al by a surface adsorption mechanism and Mn by slower oxidation of Mn2+ are consistent with these observations. A model of Mn oxidation kinetics accurately predicts the intermediate depth leachable particulate Mn maximum.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1992 , Vol. 15 , N. 6 , P. 609-619

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00101/21186/18803.pdf
http://archimer.ifremer.fr/doc/00101/21186/

Éditeur(s) : La Havane : La Propaganda literaria
Siècle(s) traité(s) : 19
Provenance : Ville de Bordeaux. Bibliothèque municipale
Permalien : http://www.manioc.org/patrimon/BBX19051
BBX19051

Éditeur(s) : Cayenne : Imprimerie du gouvernement
Résumé : Année 1858
Siècle(s) traité(s) : 19
Droits : Domaine public
Provenance : Collectivité territoriale de Guyane. Bibliothèque Alexandre-Franconie
Permalien : http://www.manioc.org/patrimon/FRA11253
FRA11253

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
A CO2-rich brine core-flood experiment in calcite limestone for conditions representative of underground storage (P = 12 MPa and T = 100°C) was performed in order to explore the dissolution mechanisms arising at moderate CO2 partial pressure (0.3 MPa). An increase of the total porosity (φT) accompanied by a persistent permeability (k) decrease was measured. The mechanisms controlling this atypical anticorrelated k − φT relationship were investigated from the analysis of high-resolution X-ray microtomography images of the sample acquired before and after the experiment. All the evidences converge to the conclusion that the ubiquitous decrease of permeability measured during the 44 h of dissolution is due to the clogging of a fraction of the macroporosity by microporous material triggered by the rearrangement of the detached undissolved particles. This mechanism results in the development of low permeability zones bridging the macroporosity.
ISSN: 0094-8276

hal-00903585
https://hal.archives-ouvertes.fr/hal-00903585
DOI : 10.1002/grl.50595

Éditeur(s) : Elsevier
Résumé : In situ microbialites occurring in reef rocks dredged between 80 and 130 in water depth on the modern fore-reef slopes of Tahiti and the Marquesas islands yield ages ranging from 17,100 2900 to 4410 2250 years BP, suggesting that they played a prominent role during the last deglacial sea level rise. Microbialites developed in both shallow and deep water depositional environments where they characterize various zones of the reef tracts (reef crests, upper reef slopes, deep fore-reef slopes), reflecting contrasting scenarios of microbialite development involving ''reefal microbialites'' in shallow-water settings and ''slope microbialites'' that formed in environments deeper than 1020 in and extending down to more than 100 m. Reefal microbialites correspond to a late stage of encrustation of the dead parts of coral colonies, or more commonly, of related encrusting organisms (red algae and foraminifers), thus forming surface crusts. Slope microbialites generally form the ultimate stage of a biological succession indicating a deepening sequence, whereby shallow water corals and associated encrusting organisms are replaced by deeper water assemblages of red algae and foraminifers before microbialite growth. The precipitation of phosphatic-iron-manganese crusts and the deposition of planktonic micritic limestones on the microbialites characterize a deepening-upward sequence. The widespread development of microbialites in reef sequences from the Last Deglaciation characterizes a period of environmental degradation consequential oil the rapid sea-level rise and abrupt climatic changes of that time. The reported biological succession reflects changes in water quality, and especially an increase in nutrients. In shallow-water settings, increased alkalinity and nutrient availability in interstitial waters were related to surface fluxes and terrestrial groundwater seepage while slope environments were exposed to continuous upwelling of nutrient-rich deeper waters during the last deglacial sea level rise. The age differences between corals and overlying slope microbialites range from 1600 to 8400 years, based on high-precision U-series age measurements of both corals and microbialites, and indicates that a significant time (several thousand years) elapsed between the development of the coralgal frameworks and the growth of slope microbialite crusts. Microbialites cannot be considered as part of the drowning event some 14,000 years ago that resulted in the demise of reef frameworks in the 90-110 m present depth range, but are Substantially younger. (c) 2006 Elsevier B.V. All rights reserved.
Sedimentary Geology (0037-0738) (Elsevier), 2006-03 , Vol. 185 , N. 3-4 , P. 277-295

Droits : 2006 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/2006/publication-4204.pdf
DOI:10.1016/j.sedgeo.2005.12.018
http://archimer.ifremer.fr/doc/00000/4204/

Éditeur(s) : HAL CCSD GIA - Gemological Institute of America
Résumé : A new opal deposit was discovered in 2008 near the village of Wegel Tena, in volcanic rocks of Ethiopia's Wollo Province. Unlike previous Ethiopian opals, the new material is mostly white, with some brown opal, fire opal, and colorless "crystal" opal. Some of it resembles Australian and Brazilian sedimentary opals, with play-of-color that is often very vivid. However, its properties are consistent with those of opal-CT and most volcanic opals. Inclusions consist of pyrite, barium-manganese oxides, and native carbon Some samples show "digit patterns", interpenetrating play-of-color and common opal, resembling fingers. The opaque-to-translucent Wegel Tena opals become transparent when soaked in water, showing a remarkable hydrophane character. White opals from this deposit contain an elevated Ba content, which has not been reported so far in opal-CT. The fire and crystal opals are prone to breakage, while the white, opaque-to-translucent opals are remarkably durable. The proportion of gem-quality material in the Wegel Tena deposit seems unusually high, and 1,500 kg have already been extracted using rudimentary mining techniques. The deposit may extend over several kilometers and could become a major source of gem-quality opal
ISSN: 0016-626X

hal-00560177
https://hal.archives-ouvertes.fr/hal-00560177

Éditeur(s) : HAL CCSD
Résumé : International audience
The Cenozoic weathering of peninsular India has been advocated as a major driver of globalcooling, however, its timing remains virtually unconstrained such that proposed links betweentropical weathering of the Deccan Traps, regional monsoonal intensity and global climate remainsspeculative. To solve this conundrum we present here a revised weathering chronologybased on the identification of lateritic paleosurfaces and their dating using 40Ar/39Ar on supergeneK-rich manganese oxides. We focus on the Indian western passive margin where theWestern Ghats Escarpment (WGE) – a ~1000 m high topographic barrier resulting from thecontinental break up of Greater India – exposes exceptionally preserved weathering profilesfrom the western coastal lowlands to the eastern highland plateaus above the WGE. Four mainlateritic paleosurfaces have been identified: Three in the highland; a high landsurface (Al-Femostly bauxite) at elevation 1200-1000 m asl, an intermediate landsurface covered by a Feduricrustat 1000-900 m asl and a lower pediment landsurface at 850-600 m asl; and one inthe coastal lowland underneath a pediment landsurface at 150-50 m asl. The 40Ar/39Ar agesdocument three major weathering periods over the Cenozoic. The oldest weathering period(W1) is recorded between 53 Ma to 45 Ma both in the highland and the lowland. This correlatesto the Global Eocene climatic Optimum, and allows defining a bauxitic paleolandsurface acrossthe escarpment. Intense bauxitic weathering between ~ 45 and 47 Ma in the lowland indicatethat the WGE was stabilized before ~ 47 Ma on its margin and also implies low denudation rateat the foot of the WGE (<5 m Ma-1) since that time. The second weathering period between37 Ma to 19 Ma (W2) occurred in two distinctive stages (W2a and W2b). From 37 to 26 (W2a),weathering is only recorded in the highland and affect intermediate surfaces. The intensityof chemical weathering decreased sensibly between 32 and 29 Ma – potentially linked to theEarly Oligocene cooling – and resulted in the formation of the lower pediment surface. From~26 Ma to 19 Ma (W2b), only the western coastal lowland weathered while the highland surfacesare mostly dissected. This change and the highland/lowland weathering mitigation after~26 Ma documents a change in climatic patterns over peninsular India that signs the onset ofmodern-like monsoon regime. These results are being interpolated to the Deccan Traps basaltsto quantify their weathering and ultimately estimate of the contribution to CO2 fluxes of thesethree weathering periods and their potential link to Asian Monsoons and global cooling.
Source to Sink: a long term perspective of sediment budgets and sources characterization, Abstracts
Rennes, France

insu-01406455
https://hal-insu.archives-ouvertes.fr/insu-01406455

Éditeur(s) : Elsevier
Résumé : The accumulation of nine heavy metals in fine-grained sediments from the mangrove fringed coast of French Guiana is evaluated. The dynamic features of the South American tropical coastline, from the Amazon to the Orinoco Rivers, result in mangrove sediments being alternately submitted to phases of erosion and net sedimentation a few tens of years long. This process influences the distribution of the heavy metals associated with these frequently re-mobilized deposits. Sedimentary cores and mangrove plant samples were collected, at different seasons, in various swamps characterized by different properties (content of sedimentary organic matter, distance from sea water and fresh water). The ranges of measured concentrations expressed in mu mol g(-1) were the following: Cu (0.06 to 0.61), Co (0.12 to 0.68), Pb (0.08 to 0.18), Ni (0.32 to 0.76), Cr (0.61 to 1.40), Zn (1.25 to 5.94), Mn (4.36 to 45.4) and Fe (441 to 1128). No differences were found between sediments from mangroves developing upstream and downstream of urban areas, i.e. Cayenne and Kourou. This suggests that the content of mangrove sediments in heavy metals along the coastline of French Guiana is essentially the result of the continuous alternation of accumulation and transport phases occurring upstream after departing from the Amazon watershed. The sources of this heavy metals content are thus difficult to identify. However it is well known that the alluvium produced by the natural erosion of the Amazonian soils is naturally enriched in mercury. Also, the run-off from gold mining activities is known to contribute to mercury pollution. Ranges in total Hg were between 0.15 and 2.57 nmol g(-1), with mean values close to 0.41 nmol g(-1), and were clearly correlated with total organic carbon except for some outstanding high values, which may be a result of rapid geochemical changes. Heavy metal concentrations showed variations with depth. The redox conditions and the decay processes affecting the organic matter control the cycling of iron and manganese, which in turn control the concentrations and associations of heavy metals. These preliminary results suggest that the variations in heavy metal content with depth or between mangrove areas result largely from diagenetic processes rather than changes in metal input resulting from local human activities. (c) 2005 Elsevier B.V. All rights reserved.
Marine Chemistry (0304-4203) (Elsevier), 2006 , Vol. 98 , N. 1 , P. 1-17

Droits : 2005 Elsevier B.V. All rights reserved
http://archimer.ifremer.fr/doc/2006/publication-1041.pdf
DOI:10.1016/j.marchem.2005.06.001
http://archimer.ifremer.fr/doc/00000/1041/

Éditeur(s) : Paris : Rousselon, Libraire-Editeur
Siècle(s) traité(s) : 19
Droits : Domaine public
Provenance : Fondation Clément
Permalien : http://www.manioc.org/patrimon/FCL18028
FCL18028

Éditeur(s) : Paris : Gide et J. Baudry, éditeurs
Siècle(s) traité(s) : 19
Provenance : Archives départementales de Guadeloupe
Permalien : http://www.manioc.org/patrimon/ADG18262
ADG18262

Éditeur(s) : HAL CCSD Elsevier
Résumé : Detailed sedimentological investigations on numerous outcrops and drill-core sections in the 2.1-Ga-old Franceville basin, Gabon, provide evidence for a large-scale injectite network. The injectites were formed by the injection of sands through a thickness of about 150 m of the FB1 Member, and now cover a minimum area of 70 km2 corresponding to the Bangombé plateau, but are also recognized close to Franceville 35 km farther south-east. The injectite lithology corresponds to a mud- or carbonate-supported sandstone characterized by a loose and uncompacted fabric contrasting with the host-rock. Because the injectites are often parallel to subparallel to the stratification, they were misinterpreted as depositional beds by previous authors. At outcrop, the injectite bodies exhibit sill, dyke, wing and protrusive geometries emplaced during early burial within poorly compacted material, with partial wall erosion and dissociation. The source of the sand material is attributed to a channel-levee turbidite depositional system located in the lower part of the FB1 Member. These deposits were buried by a thick biochemical muddy cap deposited during a starvation phase, which increased the seal capacity of the system. This type of architecture has a high potential to develop compaction disequilibrium during burial. Moreover, in the case of the Francevillian injectites, the abundance of microbial organic matter favoured early methane degassing and lateral charging of the sand reservoir. The overpressure in the channels was periodically released during early burial, through the effect of rapid sedimentary and tectonic loading, and possible seismic activity. The fluidized sand was injected according to a symmetrical wing pattern. Thus, the injected masses caused a local decrease in the grade of the lateritic manganese ore deposit of the Bangombé plateau.
ISSN: 0301-9268

hal-01667217
https://hal.archives-ouvertes.fr/hal-01667217
DOI : 10.1016/j.precamres.2017.09.022

Éditeur(s) : HAL CCSD
Résumé : Geological storage of CO2 is one of diverse technologies being explored to reduce atmospheric carbon fromindustrial processes (i.e. fossil fuel combustion). One of the specific features of CO2 injection is the possibility ofgeochemical reactions (dissolution – precipitation) between mobile reactive brine (e.g. formation water enrichedin CO2) and the host rock during the spatial and temporal evolution of CO2. That leads to modifications in thepore structure, which in turn change the flow dynamics of the reservoir (e.g. the permeability k). Then, thesesstructural modifications can largely control the injectivity, so that the pressure field in the reservoir and also theCO2 propagation. Accordingly, it is crucial to explore the changes in the reservoir properties (e.g. structural andhydrodynamic) induced during a CO2 injection and specially the relationships between them (e.g. k or reactivesurface-Sr versus porosity-φ , k versus rock heterogeneity), for developing predictive modelling tools of thetransport and reaction processes occurring during a CO2 injection and reliable risk assessment. In the case ofcarbonate rocks, the application of the predictive models of transport and reaction is still challenging, because oftheir high heterogeneity so that the incertitude in the reaction kinetics of carbonate minerals.From this perspective, we realized brine-enriched in CO2 percolation experiments through carbonate rocksamples in thermodynamic conditions expected during CO2 injection in deep reservoirs (T = 100°C et P =12MPa). The permeability changes k(t) is monitored during the experiments and the porosity variationφ (t) iscalculated from chemical analyses of the sampled outlet fluids, using ICP-EAS. The pore structure modificationsare investigated from high resolution X ray micro tomography images acquired from the synchrotron ofGrenoble (ESRF). Depending to the dissolution regime, controlled by the reservoir rock fabric and the chemicalcomposition of the brine (e.g. PCO2), we observed that a modification of pore structure can either improve(atypical result in dissolution context) or impair the value of the permeability k.
Le stockage géologique du CO2 est l’une des diverses technologies étant explorées afin deréduire les émissions de carbone atmosphérique des processus industriels (i.e. combustion del’énergie fossile). L’une des spécifiques caractéristiques de l’injection du CO2 en profondeurreste la possibilité de réactions géochimiques (dissolution-précipitation) entre la saumureréactive mobile (e.g. eau de formation enrichie en CO2) et la roche encaissante durantl’évolution spatiale et temporelle du CO2, conduisant à des modifications dans la structure despores et par conséquent dans les propriétés d’écoulement du réservoir (e.g. la perméabilité k).Donc, ces changements structuraux peuvent largement contrôler l’injectivité, ainsi que lechamp de pression dans le réservoir et aussi la propagation du CO2. Il demeure ainsi cruciald’explorer les changement dans les propriétés de réservoirs (e.g. structurales ethydrodynamiques) induits durant une injection de CO2 et explicitement les relations existantesentre eux (e.g. k ou surface réactive-Sr versus porosité-φ , k versus hétérogénéité de la roche),afin de développer des outils de modélisation prédictive des processus de transport etréactionnels se produisant durant une injection de CO2 et d’évaluer de façon fiable les risques.Dans le cas des réservoirs carbonatés, l’application des modèles prédictifs de transport réactifdemeure toujours un enjeu, car contrainte par la forte hétérogénéité en leur sein ainsi que parl’incertitude dans la cinétique de réactions des minéraux carbonatés dans ce contexte. Danscette optique, nous avons réalisé des expériences de percolation à travers des échantillons deroches carbonatées dans les conditions thermodynamiques de stockage en profondeur (T =100°C et P =12 MPa). L’évolution de la perméabilité k(t) est suivie au cours desexpériences ; et la variation de la porosité φ (t) est calculée à partir des résultats d’analyseschimiques au ICP-AES des fluides de sortie échantillonnés. L’investigation des modificationsapportées à la structure des pores est réalisée par le biais de la Micro-Tomographie hauterésolution à rayon X, acquise au synchrotron de Grenoble (e.g. ESRF).Dépendant du régime de dissolution, contrôlé par la fabrique de la roche réservoir et lacomposition chimique de la saumuré chargée en CO2 (e.g. PCO2 engagée), on a observéqu’une modification de la structure de la roche peut soit améliorer soit détériorer (résultatatypique en contexte de dissolution) la valeur de la perméabilité k.
https://hal.archives-ouvertes.fr/tel-01142136

tel-01142136
https://hal.archives-ouvertes.fr/tel-01142136
https://hal.archives-ouvertes.fr/tel-01142136/document
https://hal.archives-ouvertes.fr/tel-01142136/file/thesemangane2013.pdf

Éditeur(s) : Paris : Association d'imprimeurs
Siècle(s) traité(s) : 20
Droits : Domaine public
Provenance : Collectivité territoriale de Guyane. Bibliothèque Alexandre-Franconie
Permalien : http://www.manioc.org/patrimon/FRA12350
FRA12350

Éditeur(s) : Paris : Librairie orientale et américaine, E. Guimolto

Droits : Domaine public
Provenance : Institut des Hautes Études de l'Amérique latine, Bibliothèque Pierre-Monbeig
Permalien : http://www.manioc.org/patrimon/IHE14017
IHE14017

Éditeur(s) : HAL CCSD Geological Society of America
Résumé : International audience
The post-rift denudation history of high-elevation divergent continental margins is central to deciphering source-to-sink systems across such margins and to unraveling their topographic evolution. We performed 40Ar-39Ar dating of supergene K-Mn oxides from supergene manganese ore deposits in order to constrain the age of in situ formed laterites on both the lowland and highland sides of the Western Ghats Escarpment of Peninsular India. Documentation of laterites as old as 53 Ma on the highland and 47 Ma at the foot of the escarpment shows that the escarpment stabilized before 47 Ma (possibly 60 Ma). The topographic setting of the dated weathering mantles also constrains denudation of the lowland and the highland since ca. 50 Ma to maximums of 5 m/m.y. and 15 m/m.y., respectively. Our results challenge denudation rates derived from apatite fission track thermochronology by documenting the topography and relief longevity of the southwest Indian margin and its hinterland. The results preclude large-magnitude uplift of Peninsular India after the Eocene, and more generally argue against late Neogene uplift and topographic rejuvenation of continental shields.
ISSN: 0091-7613

hal-01306559
https://hal.archives-ouvertes.fr/hal-01306559
DOI : 10.1130/G37303.1

Éditeur(s) : Cayenne : Société d'études et d'exploitations minières de l'Inini (S.E.E.M.I)
Résumé : "Carnet de calques agrafés brouillon du texte "Année 1943 résumé des travaux effectués n°2"
Siècle(s) traité(s) : 20
Droits : Domaine public
Provenance : ORkidé|BRGM Guyane
Permalien : http://www.manioc.org/patrimon/ORK13051
ORK13051

Éditeur(s) : Paris : Librairie Larousse
Extrait de : Atlas colonial illustré
Résumé : Fascicule 24 de l'Atlas colonial illustré composé de 25 fascicules, pp. 257 à 260 concernant l'or en Guyane française
Siècle(s) traité(s) : 20
Droits : Domaine public
Provenance : ORkidé|Association Le Planeur Bleu (Cacao), Collection Philippe Soler
Permalien : http://www.manioc.org/patrimon/ORK13057
ORK13057

Éditeur(s) : Paris : Dusacq

Provenance : Archives départementales de Guadeloupe
Permalien : http://www.manioc.org/patrimon/ADG18219
ADG18219

Éditeur(s) : Fort-de-France : Imprimerie du Gouvernement
Extrait de : Bulletin agricole
Résumé : Revue sur l'agriculture tropicale
Vol. VII - n° 3 & 4, décembre 1938
Siècle(s) traité(s) : 20
Provenance : Fondation Clément
Permalien : http://www.manioc.org/patrimon/FCL18030
FCL18030

Éditeur(s) : Fort-de-France : Imprimerie du Gouvernement
Siècle(s) traité(s) : 19
Droits : Domaine public
Provenance : Communauté d'agglomération de La Rochelle. Médiathèque Michel-Crépeau
Permalien : http://www.manioc.org/patrimon/MMC16033
MMC16033