Papers by Frederic Candaudap
Because of the complex bathymetry of the Southwest Atlantic, pathways of the deep waters to the A... more Because of the complex bathymetry of the Southwest Atlantic, pathways of the deep waters to the Argentine basin are not fully determined (Ahran et al., Deep Sea Res., 1999). In addition, Albarede et al. (Geochimica Acta, 1997) showed that the Nd isotopic signature of manganese nodules collected in this area is different from the surrounding bottom seawater, which could indicate
Toxic monomethylmercury (MMHg) accumulates to harmful levels along the marine food chain and pres... more Toxic monomethylmercury (MMHg) accumulates to harmful levels along the marine food chain and presents a health risk at a global scale. The origin of MMHg in the marine water column is under debate. Bacterial methylation of inorganic Hg in sediments and in the oceanic water column may be in play. We investigated MMHg distributions in the contrasted basins of the Mediterranean Sea as part of the GOSHIP cruise M84/3 on RV Meteor. The 8 full depth vertical profiles cover a West-East transect from oligotrophic to ultra-oligotrophic waters. MeHg concentrations were generally higher in the more productive Western Basin. Our findings suggest that quantity and the quality of phytoplankton may influence the production of MeHg in the oceanic water column.
Journal of Glaciology - J GLACIOLOGY, 1995
Mineralogical Magazine, 2012
Granitic pegmatites are exceptional igneous rocks and the possible role of an immiscibility proce... more Granitic pegmatites are exceptional igneous rocks and the possible role of an immiscibility process in their origin is strongly debated. To investigate metal and metalloid behaviour in hydrous peraluminous systems (aluminium saturation index, ASI >1), we analysed 15 quartz-hosted primary melt and fluid inclusions from pegmatites in the Ehrenfriedersdorf Complex (Erzgebirge, Germany) and 26 primary melt inclusions from leucogranites of the Ehrenfriedersdorf district (Germany), Kymi (Finland) and Erongo (Namibia) by femtosecond laser ablation inductively coupled plasma quadrupole mass spectrometry. The results presented here for 32 elements provide evidence for metal and metalloid fractionation between two types of immiscible melts (A and B) and NaClÀHCl-rich brine in the pegmatite system. No evidence for the boundary layer effect was observed in the 40À500 mm size melt inclusions that were investigated. The data on the Ehrenfriedersdorf pegmatites allow quantification of the metal and metalloid partitioning between natural NaCl-rich brine and the two types of melt (e.g. K As brine/type-A,B melts = 0.01À1.7; K Sb brine/type-A,B melts = 10À285; K Zn brine/type-A,B melts 5 50; K Pb brine/type-A melt 5 50; K Ag brine/type-A melt = 46). These data are in accord with existing natural and experimental data on equilibrium fluidÀmelt partitioning as well as spectroscopic data on the metal and metalloid complexation in hydrous aluminosilicate melts and NaClÀHCl-rich fluids.
Journal of Analytical Atomic Spectrometry, 2008
... Femtosecond LA-ICP-MS thus provides more stable signals, lower noise levels and more reproduc... more ... Femtosecond LA-ICP-MS thus provides more stable signals, lower noise levels and more reproducible experiments.10 Femtosecond ablation should also be less dependant on the laser wavelength.24 In this paper, we report on systematic studies of the effect of the pulse ...
Geochimica et Cosmochimica Acta, 2006
The dacite pumice erupted from Mt. Pinatubo on June 15, 1991 (whole-rock, rhyolitic groundmass gl... more The dacite pumice erupted from Mt. Pinatubo on June 15, 1991 (whole-rock, rhyolitic groundmass glasses and homogenized melt inclusions) has been analyzed using inductively coupled plasma-mass spectrometry (ICP-MS), nanosecond and femtosecond laser ablation ICP-MS and secondary ion mass spectrometry (SIMS) to evaluate its ore-forming potential. Data suggest that adakite magmas are metal-rich and concentrate ore metals during magmatic differentiation. Sulfides segregate in limited amounts under the hydrous, oxidizing conditions typical of adakitic magmas resulting in incompatible behavior for Au (6-22 ppb), Cu (26-77 ppm), and Pb, Mo, As, and Sb in melts of dacitic to rhyolitic compositions. Metal transfer from this adakite magma to the coexisting aqueous phase was favored by the peraluminous composition of the rhyolitic melt and high aqueous chloride concentrations. Mass balance calculations suggest that the pre-eruptive aqueous phase could have extracted a minimum of 100 t Au and 5 · 10 5 t Cu from the Mt. Pinatubo magma. Our data suggest that intrusives having adakitic signatures are genetically associated with Au-Cu and Cu-Mo mineralization, auriferous porphyry copper deposits, and epithermal gold veins. High H 2 O, Cl, Sr/Y, Pb/Ce, Mo/Ce, As/Ce and Sb/Ce in Mt. Pinatubo melts reflect the contribution of deep fluids derived from subducted sediments and altered MORBs in the dacite genesis. The slab-derived fluids carrying mobile elements are likely responsible for the enrichment of adakite magmas in gold, associated metals and H 2 O, and may explain the exceptional ore-forming potential of adakite magmatism.
American Mineralogist, 2009
We used configurational entropy theory to model the viscosity (η) of hydrous melts of NaAlSi 3 O ... more We used configurational entropy theory to model the viscosity (η) of hydrous melts of NaAlSi 3 O 8 , haplogranite (SiO 2 -KAlSi 3 O 8 -NaAlSi 3 O 8 ), and complex (natural) granite composition from available measurements and recently published configurational heat-capacity data. The equation log η = A e + B e /TS conf (T), where S conf is configurational entropy, reproduces viscosity data for individual samples as well as or better than the empirical three-parameter TVF equation (defined below), and has the advantage of being based on thermodynamic theory. The variables A e , B e , and S conf (T g ), where T g is glass transition temperature, were parameterized as a function of water content for compilations of viscosity data for hydrous NaAlSi 3 O 8 , haplogranite, and peraluminous granite melts. With the simplest assumption of ideal mixing between silicate and water components, configurational entropy models with between 4 and 10 fitting parameters reproduce experimentally determined η-T-X H2O relationships significantly better than previous literature models based on empirical equations. Our preferred configurational entropy models have root-mean-square deviations of 0.26 log units for NaAlSi 3 O 8 (n = 77), 0.16 log units for haplogranite (n = 55), and 0.28 log units for peraluminous granites (n = 79). The best statistical fits to the data sometimes require thermodynamically unlikely variations in A e , B e , and S conf (T g ) as a function of water content, however, such that further calorimetry data are needed to extract accurate thermodynamic information from viscosity data sets for hydrous melts.
Palaeogeography, Palaeoclimatology, Palaeoecology, 2013
To precisely reconstruct environmental changes from high-resolution bivalve shell geochemistry, t... more To precisely reconstruct environmental changes from high-resolution bivalve shell geochemistry, the shell layers must represent environmental conditions at the time of deposition. Therefore, calcium carbonate along growth lines that formed at the same time should show the same geochemical signature. We test this assumption by evaluating the geochemical spatial homogeneity along growth layers (i.e., shell secreted at a given time)
Geochimica et Cosmochimica Acta, 2007
Mollusk shells are increasingly used as records of past environmental conditions, particularly fo... more Mollusk shells are increasingly used as records of past environmental conditions, particularly for sea-surface temperature (SST) reconstructions. Many recent studies tackled SST (and/or sea-surface salinity) tracers through variations in the elementary (Mg and Sr) or stable isotope (d 18 O) composition within mollusk shells. But such attempts, which sometimes include calibration studies on modern specimens, are not always conclusive. We present here a series of Mg and Sr analyses in the calcitic layer of Concholepas concholepas (Muricidae, Gastropoda) with a very high time-resolution on a time window covering about 1 and a half month of shell formation, performed by Laser Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICP-MS) and electron probe micro-analysis (EPMA). The selected specimen of this common Chilean gastropod was grown under controlled environmental conditions and precise weekly time-marks were imprinted in the shell with calcein staining. Strontium variations in the shell are too limited to be interpreted in terms of environmental parameter changes. In contrast, Mg incorporation into the shell and growth rate appear to change systematically between night and day. During the day, Mg is incorporated at a higher rate than at night and this intake seems positively correlated with water temperature. The nightly reduced Mg incorporation is seemingly related to metabolically controlled processes, formation of organic-rich shell increments and nocturnal feeding activity of the animals. The nyctemeral Mg changes in the C. concholepas shell revealed in this study might explain at least part of the discrepancies observed in previous studies on the use of Mg as a SST proxy in mollusk shells. In the case of C. concholepas, Mg cannot be used straightforwardly as a SST proxy.
préparation de matériaux de référence par la technique de fusion.
Geostandards and Geoanalytical Research, 2010
préparation de matériaux de référence par la technique de fusion.
Geostandards and Geoanalytical Research, 2008
Vol. 32 -N°2 p . 2 0 9 -2 2 9
Geochimica et Cosmochimica Acta, 2007
Mollusk shells are increasingly used as records of past environmental conditions, particularly fo... more Mollusk shells are increasingly used as records of past environmental conditions, particularly for sea-surface temperature (SST) reconstructions. Many recent studies tackled SST (and/or sea-surface salinity) tracers through variations in the elementary (Mg and Sr) or stable isotope (d 18 O) composition within mollusk shells. But such attempts, which sometimes include calibration studies on modern specimens, are not always conclusive. We present here a series of Mg and Sr analyses in the calcitic layer of Concholepas concholepas (Muricidae, Gastropoda) with a very high time-resolution on a time window covering about 1 and a half month of shell formation, performed by Laser Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICP-MS) and electron probe micro-analysis (EPMA). The selected specimen of this common Chilean gastropod was grown under controlled environmental conditions and precise weekly time-marks were imprinted in the shell with calcein staining. Strontium variations in the shell are too limited to be interpreted in terms of environmental parameter changes. In contrast, Mg incorporation into the shell and growth rate appear to change systematically between night and day. During the day, Mg is incorporated at a higher rate than at night and this intake seems positively correlated with water temperature. The nightly reduced Mg incorporation is seemingly related to metabolically controlled processes, formation of organic-rich shell increments and nocturnal feeding activity of the animals. The nyctemeral Mg changes in the C. concholepas shell revealed in this study might explain at least part of the discrepancies observed in previous studies on the use of Mg as a SST proxy in mollusk shells. In the case of C. concholepas, Mg cannot be used straightforwardly as a SST proxy.
The natural river water certified reference material SLRS-5 (NRC-CNRC) was routinely analysed in ... more The natural river water certified reference material SLRS-5 (NRC-CNRC) was routinely analysed in this study for major and trace elements by ten French laboratories. Most of the measurements were made using ICP-MS. Because no certified values are assigned by NRC-CNRC for silicon and 35 trace element concentrations (rare earth elements, Ag, B, Bi, Cs, Ga, Ge, Li, Nb, P, Rb, Rh, Re, S, Sc, Sn, Th, Ti, Tl, W, Y and Zr), or for isotopic ratios, we provide a compilation of the concentrations and related uncertainties obtained by the participating laboratories. Strontium isotopic ratios are also given.
Journal of Analytical Atomic Spectrometry, 2013
The rare earth elements (REEs) are valuable tracers in the earth, ocean and environmental science... more The rare earth elements (REEs) are valuable tracers in the earth, ocean and environmental sciences. Ten out of fourteen stable REEs have two or more isotopes, making them suitable for quantification by isotope dilution.
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Papers by Frederic Candaudap