Nordine Bouden

@article{Bouden_etal2021,

title = {Triple oxygen isotope measurements by multi-collector secondary ion mass spectrometry},

author = {N. Bouden and J. Villeneuve and Y. Marrocchi and E. Deloule and E. F\"{u}ri and A. Gurenko and L. Piani and E. Thomassot and P. Peres and F. Fernandes},

doi = {doi: 10.3389/feart.2020.601169},

year  = {2021},

date = {2021-01-01},

journal = {Frontiers in Earth Science},

pages = {8:601169},

abstract = {Secondary ion mass spectrometry (SIMS) is a powerful technique for in situ triple oxygen isotope measurements that has been used for more than 30 years. Since pioneering works performed on small-radius ion microprobes in the mid-80s, tremendous progress has been made in terms of analytical precision, spatial resolution and analysis duration. In this respect, the emergence in the mid-90s of the large-radius ion microprobe equipped with a multi-collector system (MC-SIMS) was a game changer. Further developments achieved on CAMECA MC-SIMS since then (e.g., stability of the electronics, enhanced transmission of secondary ions, automatic centering of the secondary ion beam, enhanced control of the magnetic field, 1012$\Omega$ resistor for the Faraday cup amplifiers) allow nowadays to routinely measure oxygen isotopic ratios (18O/16O and 17O/16O) in various matrices with a precision (internal error and reproducibility) better than 0.5texttenthousand (2$sigma$), a spatial resolution smaller than 10 $mu$m and in a few minutes per analysis. This paper focuses on the application of the MC-SIMS technique to the in situ monitoring of mass-independent triple oxygen isotope variations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Cavalazzi_etal2021,

title = {Cellular remains in a 3.42-billion-year-old subseafloor hydrothermal environment},

author = {B. Cavalazzi and L. Lemelle and A. Simionovici and S. L. Cady and M. J. Russell and E. Bailo and R. Canteri and E. Enrico and A. Manceau and A. Maris and M. Salom\'{e} and E. Thomassot and N. Bouden and R. Tucoulou and A. Hofmann},

doi = {10.1126/sciadv.abf3963},

year  = {2021},

date = {2021-01-01},

journal = {Science Advances},

volume = {7},

number = {29},

pages = {eabf3963},

abstract = {Subsurface habitats on Earth host an extensive extant biosphere and likely provided one of Earthtextquoterights earliest microbial habitats. Although the site of lifetextquoterights emergence continues to be debated, evidence of early life provides insights into its early evolution and metabolic affinity. Here, we present the discovery of exceptionally well-preserved, 3.42-billion-year-old putative filamentous microfossils that inhabited a paleo-subseafloor hydrothermal vein system of the Barberton greenstone belt in South Africa. The filaments colonized the walls of conduits created by low-temperature hydrothermal fluid. Combined with their morphological and chemical characteristics as investigated over a range of scales, they can be considered the oldest methanogens and/or methanotrophs that thrived in an ultramafic volcanic substrate.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gress_etal2021_3,

title = {Two billion years of episodic and simultaneous websteritic and eclogitic diamond formation beneath the Orapa kimberlite cluster, Botswana},

author = {M. U. Gress and S. Timmerman and I. L. Chinn and J. M. Koornneef and E. Thomassot and E. A. S. Valk and K. Zuilen and N. Bouden and G. R Davies},

doi = {10.1007/s00410-021-01802-8},

year  = {2021},

date = {2021-01-01},

journal = {Contributions to Mineralogy and Petrology},

volume = {176},

number = {54},

abstract = {The Sm--Nd isotope systematics and geochemistry of eclogitic, websteritic and peridotitic garnet and clinopyroxene inclusions together with characteristics of their corresponding diamond hosts are presented for the Letlhakane mine, Botswana. These data are supplemented with new inclusion data from the nearby (20--30 km) Orapa and Damtshaa mines to evaluate the nature and scale of diamond-forming processes beneath the NW part of the Kalahari Craton and to provide insight into the evolution of the deep carbon cycle. The Sm--Nd isotope compositions of the diamond inclusions indicate five well-defined, discrete eclogitic and websteritic diamond-forming events in the Orapa kimberlite cluster at 220 textpm 80 Ma, 746 textpm 100 Ma, 1110 textpm 64 Ma, 1698 textpm 280 Ma and 2341 textpm 21 Ma. In addition, two poorly constrained events suggest ancient eclogitic (\> 2700 Ma) and recent eclogitic and websteritic diamond formation (\< 140 Ma). Together with sub-calcic garnets from two harzburgitic diamonds that have Archaean Nd mantle model ages (TCHUR) between 2.86 and 3.38 Ga, the diamonds studied here span almost the entire temporal evolution of the SCLM of the Kalahari Craton. The new data demonstrate, for the first time, that diamond formation occurs simultaneously and episodically in different parageneses, reflecting metasomatism of the compositionally heterogeneous SCLM beneath the area ( 200 km2). Diamond formation can be directly related to major tectono-magmatic events that impacted the Kalahari Craton such as crustal accretion, continental breakup and large igneous provinces. Compositions of dated inclusions, in combination with marked variations in the carbon and nitrogen isotope compositions of the host diamonds, record mixing arrays between a minimum of three components (A : peridotitic mantle ; B : eclogites dominated by mafic material ; C : eclogites that include recycled sedimentary material). Diamond formation appears dominated by local fluid--rock interactions involving different protoliths in the SCLM. Redistribution of carbon during fluid--rock interactions generally masks any potential temporal changes of the deep carbon cycle.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Casola_etal2020,

title = {No evidence for carbon enrichment in the mantle source of carbonatites in eastern Africa},

author = {V. Casola and L. France and A. Galy and N. Bouden and J. Villeneuve},

doi = {10.1130/G47629.1},

year  = {2020},

date = {2020-01-01},

journal = {Geology},

volume = {48},

pages = {971--975},

abstract = {Carbonatites are unusual, carbon-rich magmas thought to form either by the melting of a carbon-rich mantle source or by low-degree partial melting of a carbon-poor (\<80 ppm C) mantle followed by protracted differentiation and/or immiscibility. Carbonate-bearing mantle xenoliths from Oldoinyo Lengai (East African Rift), the only active volcano erupting carbonatites, have provided key support for a C-rich mantle source. Here, we report unique microscale O and C isotopic analyses of those carbonates, which are present as interstitial grains in the silicate host lava, veins in the xenoliths, and pseudo-inclusions in olivine xenoliths. The $delta$18O values vary little, from 19texttenthousand to 29texttenthousand, whereas $delta$13C values are more variable, ranging from --23texttenthousand to +0.5texttenthousand. We show that such carbonate $delta$18O values result from the low-temperature precipitation of carbonate in equilibrium with meteoric water, rather than under mantle conditions. In this framework, the observed $delta$13C values can be reproduced by Rayleigh distillation driven by carbonate precipitation and associated degassing. Together with petrological evidence of a physical connection between the three types of carbonates, our isotopic data support the pedogenic formation of carbonates in the studied xenoliths by soil-water percolation and protracted crystallization along xenolith cracks. Our results refute a mechanism of C enrichment in the form of mantle carbonates in the mantle beneath the Natron Lake magmatic province and instead support carbonatite formation by low-degree partial melting of a C-poor mantle and subsequent protracted differentiation of alkaline magmas.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Decraene_etal2020,

title = {High spatial resolution measurements of iron isotopes in pyrites by SIMS using the new Hyperion‐II Radio‐Frequency Plasma source},

author = {M. N. Decraene and J. Marin-Carbonne and A. S. Bouvier and J. Villeneuve and N. Bouden and B. Luais and E. Deloule},

doi = {10.1002/rcm.8986},

year  = {2020},

date = {2020-01-01},

journal = {Rapid Communications in Mass Spectrometry},

pages = {e8986},

abstract = {RationaleIron isotopic signatures in pyrites are considered as a good proxy to reconstruct paleoenvironmental and local redox conditions. However, the investigation of micro‐pyrites less than 20$mu$m in size has been limited by the evaluable analytical techniques. The development of the new brighter radio‐frequency plasma ion source (Hyperion‐II source) enhances the spatial resolution by increasing the beam density 10 times compared with the Duoplasmatron source.MethodsHere we present high spatial resolution measurements of iron isotopes in pyrites using a 3nA‐3$mu$m primary 16O‐ beam on two Cameca IMS 1280‐HR2 ion microprobe instruments equipped with Hyperion sources at CRPG‐IPNT (France) and at SwissSIMS (Switzerland). We tested analytical effects, such as topography and crystal orientation that could induce analytical biases perceptible through variations of the Instrumental Mass Fractionation (IMF).ResultsThe $delta$56Fe reproducibility for the Balmat pyrite standard is textpm0.25texttenthousand (2SD, standard deviation) and the typical individual internal error is textpm0.10texttenthousand (2SE, standard error). The sensitivity on 56Fe+ was 1.2x107cps/nA/ppm or better. Tests on Balmat pyrites revealed that neither the crystal orientation nor channeling effects seem to significantly influence the IMF. Different pyrite standards (Balmat and SpainCR) were used to test the accuracy of the measurements. Indium mounts must be carefully prepared with sample topography \< 2$mu$m, which was checked using an interferometric microscope. Such a topography is negligible for introducing change in the IMF. This new source increases the spatial resolution while maintaining the high precision of analyses and the overall stability of the measurements compared with the previous Duoplasmatron source.ConclusionsWe developed a reliable method to perform accurate and high‐resolution measurements of micrometric pyrites. The investigation of sedimentary micro‐pyrites will improve our understanding of the processes and environmental conditions during pyrite precipitation, including contribution of primary (microbial activities or abiotic reactions) and secondary signatures (diagenesis and/or hydrothermal fluid circulation).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kitayama_etal2017,

title = {Co-magmatic sulfides and sulfates in the Udachnaya-East pipe (Siberia): A record of the redox state and isotopic composition of sulfur in kimberlites and their mantle sources},

author = {Y. Kitayama and E. Thomassot and A. Galy and A. Golovin and A. Korsakov and E. DtextquoterightEyrames and N. Assayag and N. Bouden and D. Ionov},

doi = {10.1016/j.chemgeo.2016.10.037},

year  = {2017},

date = {2017-01-01},

journal = {Chemical Geology},

volume = {455},

pages = {315--330},

abstract = {Kimberlites of the Udachnaya-East pipe (Siberia) include a uniquely dry and serpentine-free rock type with anomalously high contents of chlorine (Cl ≤ 6.1 wt%), alkalies (Na2O + K2O ≤ 10 wt%) and sulfur (S ≤ 0.50 wt%), referred to as a textquotelefttextquoteleftsaltytextquoterighttextquoteright kimberlite. The straightforward interpretation is that the Na-, K-, Cl- and S-rich components originate directly from a carbonate-chloride kimberlitic magma that is anhydrous and alkali-rich. However, because brines and evaporites are present on the Siberian craton, previous studies proposed that the kimberlitic magma was contaminated by the assimilation of salt-rich crustal rocks. To clarify the origin of high Cl, alkalies and S in this unusual kimberlite, here we determine its sulfur speciation and isotopic composition and compare it to that of non-salty kimberlites and kimberlitic breccia from the same pipe, as well as potential contamination sources (hydrothermal sulfides and sulfates, country-rock sediment and brine collected in the area). The average $delta$34S of sulfides is−1.4 textpm 2.2texttenthousand in the salty kimberlite, 2.1 textpm 2.7texttenthousand in the non-salty kimberlites and 14.2 textpm 5.8texttenthousand in the breccia. The average $delta$34S of sulfates in the salty kimberlites is 11.1 textpm 1.8texttenthousand and 27.3textpm 1.6texttenthousand in the breccia. In contrast, the $delta$34S of potential contaminants range from 20 to 42texttenthousand for hydrothermal sulfides, from 16 to 34texttenthousand for hydrothermal sulfates, 34texttenthousand for a country-rock sediment (Chukuck suite) and the regional brine aquifer. Our isotope analyses show that (1) in the salty kimberlites, neither sulfates nor sulfides can be simply explained by brine infiltration, hydrothermal alteration or the assimilation of known salt-rich country rocks and instead, we propose that they are late magmatic phases ; (2) in the non-salty kimberlite and breccia, brine infiltration lead to sulfate reduction and the formation of secondary sulfides -- this explains the removal of salts, alkali-carbonates and sulfates, as well as theminor olivine serpentinization ; (3) hydrothermal sulfur was added to the kimberlitic breccia, but not to the massive kimberlites. In situ measurements of sulfides confirm this scenario, clearly showing the addition of two sulfide populations in the breccia (pyrite-pyrrhotites with average $delta$34S of 7.9 textpm 3.4texttenthousand and chalcopyrites with average $delta$34S of 38.0 textpm 0.4texttenthousand) whereas the salty and non-salty kimberlites preserve a unique population of djerfisherites (Cl- and K-rich sulfides) with $delta$34S values within themantle range. This study provides the first direct evidence of alkaline igneous rocks in which magmatic sulfate ismore abundant than sulfide. Although sulfates have been rarely reported in mantle materials, sulfate rich melts may be more common in the mantle than previously thought and could balance the sulfur isotope budget of Earthtextquoterights mantle.},

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pubstate = {published},

tppubtype = {article}

}