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Papers by Christine Franke

Magnetotactic bacteria produce chains of magnetite1,2 and/or greigite3–5 crystals within their ce... more Magnetotactic bacteria produce chains of magnetite1,2 and/or greigite3–5 crystals within their cell bodies called magnetosomes that are permanently magnetized6. They use these magnets to navigate along geomagnetic field lines to reach their preferred habitat7. Greigite magnetosomes have been well documented in modern sedimentary environments, but their identification in the fossil record remains controversial. Here we use transmission electron microscopy, electron diffraction patterns and rockmagnetic analyses to assess the origins of nanometre-scale greigite crystals found in Pliocene claystones from the Carpathian foredeep of Romania. We find that, like modern magnetosomal greigite grains, the crystals are single domain8, with few crystallographic defects and an overall shape consistent with an intracellular origin. We suggest these crystals are magnetosomal in origin, which would place them among

Nanomaterials

A set of three commercial zeolites (13X, 5A, and 4A) of two distinct shapes have been characteriz... more A set of three commercial zeolites (13X, 5A, and 4A) of two distinct shapes have been characterized: (i) pure zeolite powders and (ii) extruded spherical beads composed of pure zeolite powders and an unknown amount of binder used during their preparation process. The coupling of gas porosimetry experiments using argon at 87 K and CO2 at 273 K allowed determining both the amount of the binder and its effect on adsorption properties. It was evidenced that the beads contain approximately 25 wt% of binder. Moreover, from CO2 adsorption experiments at 273 K, it could be inferred that the binder present in both 13X and 5A zeolites does not interact with the probe molecule. However, for the 4A zeolite, pore filling pressures were shifted and strong interaction with CO2 was observed leading to irreversible adsorption of the probe. These results have been compared to XRD, IR spectroscopy, and ICP-AES analysis. The effect of the binder in shaped zeolite bodies can thus have a crucial impact o...

Les techniques de preparation des echantillons pour l'analyse mineralogique des mineraux argi... more Les techniques de preparation des echantillons pour l'analyse mineralogique des mineraux argileux sont presentees. Ces techniques consistent essentiellement a extraire une fraction fine (enrichie en argiles) a partir d'echantillons geologiques. Puis sont presentes les traitements de cette fraction enrichie en argiles en vue de leur analyse par diffraction des Rayons X. Enfin sont presentees les bases de la determination des mineraux argileux par diffraction RX et l'interpretation des parametres de cristallinite qui peuvent etre extraits de ces diagrammes.

Although paleogeographic time markers are available in sedimentary basin, where all strata are ch... more Although paleogeographic time markers are available in sedimentary basin, where all strata are chronologically stacked, there is still a lack of such markers for the crystalline basement. This limits the knowledge about the temporal evolution of the continental basement areas. The alteration process of albitization affects both, crystalline and sedimentary rocks, and seems to be highly abundant in the European Palaeozoic basement. Therefore, it could probably be use as a tool to develop time markers for the reconstruction of basement erosion.

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

The EGU General Assembly, 2010

The EGU General Assembly, 2016

In France, erosion by water runoff is estimated to 1.5 t ha −1 yr −1 and can exceed 10 t ha −1 yr... more In France, erosion by water runoff is estimated to 1.5 t ha −1 yr −1 and can exceed 10 t ha −1 yr −1 in large growing areas, such as the North of France (Nord-Pas-de-Calais). In this region, the Canche watershed (1294 km 2) sustains heavy loss of fertile soils. The land use is mainly dominated by arable lands (80%) and in 2013, 104 kt of suspended sediment transited to the estuary. As demonstrated in literature, agricultural soil erosion leads to the gradual disappearance and depletion of fertile soil, which constitute a non-renewable resource at human time scale. Additionally, water erosion can significantly damage the aquatic habitat and can be responsible for the input of nutrients , bacteria, pesticides, heavy metals and radionuclides into surface waters. Conscious of these effects, many programs have emerged in the Nord-Pas-de-Calais to reduce erosion. This study presents a combination of environmental magnetic proxy parameters and geochemical analyses on sediments and suspende...

Magnetotactic bacteria produce chains of magnetite1,2 and/or greigite3–5 crystals within their ce... more Magnetotactic bacteria produce chains of magnetite1,2 and/or greigite3–5 crystals within their cell bodies called magnetosomes that are permanently magnetized6. They use these magnets to navigate along geomagnetic field lines to reach their preferred habitat7. Greigite magnetosomes have been well documented in modern sedimentary environments, but their identification in the fossil record remains controversial. Here we use transmission electron microscopy, electron diffraction patterns and rockmagnetic analyses to assess the origins of nanometre-scale greigite crystals found in Pliocene claystones from the Carpathian foredeep of Romania. We find that, like modern magnetosomal greigite grains, the crystals are single domain8, with few crystallographic defects and an overall shape consistent with an intracellular origin. We suggest these crystals are magnetosomal in origin, which would place them among

Nanomaterials

A set of three commercial zeolites (13X, 5A, and 4A) of two distinct shapes have been characteriz... more A set of three commercial zeolites (13X, 5A, and 4A) of two distinct shapes have been characterized: (i) pure zeolite powders and (ii) extruded spherical beads composed of pure zeolite powders and an unknown amount of binder used during their preparation process. The coupling of gas porosimetry experiments using argon at 87 K and CO2 at 273 K allowed determining both the amount of the binder and its effect on adsorption properties. It was evidenced that the beads contain approximately 25 wt% of binder. Moreover, from CO2 adsorption experiments at 273 K, it could be inferred that the binder present in both 13X and 5A zeolites does not interact with the probe molecule. However, for the 4A zeolite, pore filling pressures were shifted and strong interaction with CO2 was observed leading to irreversible adsorption of the probe. These results have been compared to XRD, IR spectroscopy, and ICP-AES analysis. The effect of the binder in shaped zeolite bodies can thus have a crucial impact o...

Les techniques de preparation des echantillons pour l'analyse mineralogique des mineraux argi... more Les techniques de preparation des echantillons pour l'analyse mineralogique des mineraux argileux sont presentees. Ces techniques consistent essentiellement a extraire une fraction fine (enrichie en argiles) a partir d'echantillons geologiques. Puis sont presentes les traitements de cette fraction enrichie en argiles en vue de leur analyse par diffraction des Rayons X. Enfin sont presentees les bases de la determination des mineraux argileux par diffraction RX et l'interpretation des parametres de cristallinite qui peuvent etre extraits de ces diagrammes.

Although paleogeographic time markers are available in sedimentary basin, where all strata are ch... more Although paleogeographic time markers are available in sedimentary basin, where all strata are chronologically stacked, there is still a lack of such markers for the crystalline basement. This limits the knowledge about the temporal evolution of the continental basement areas. The alteration process of albitization affects both, crystalline and sedimentary rocks, and seems to be highly abundant in the European Palaeozoic basement. Therefore, it could probably be use as a tool to develop time markers for the reconstruction of basement erosion.

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

The EGU General Assembly, 2010

The EGU General Assembly, 2016

In France, erosion by water runoff is estimated to 1.5 t ha −1 yr −1 and can exceed 10 t ha −1 yr... more In France, erosion by water runoff is estimated to 1.5 t ha −1 yr −1 and can exceed 10 t ha −1 yr −1 in large growing areas, such as the North of France (Nord-Pas-de-Calais). In this region, the Canche watershed (1294 km 2) sustains heavy loss of fertile soils. The land use is mainly dominated by arable lands (80%) and in 2013, 104 kt of suspended sediment transited to the estuary. As demonstrated in literature, agricultural soil erosion leads to the gradual disappearance and depletion of fertile soil, which constitute a non-renewable resource at human time scale. Additionally, water erosion can significantly damage the aquatic habitat and can be responsible for the input of nutrients , bacteria, pesticides, heavy metals and radionuclides into surface waters. Conscious of these effects, many programs have emerged in the Nord-Pas-de-Calais to reduce erosion. This study presents a combination of environmental magnetic proxy parameters and geochemical analyses on sediments and suspende...