Nature and origin of natural Zn clay minerals from the Bou Arhous Zn ore deposit: Evidence from electron microscopy (SEM-TEM) and stable isotope compositions (H and O)
International audience; Zn-clay minerals have been found in the non-sulfide deposit of Bou Arhous (High Atlas, Morocco). They occur as white or ochre clays embedding willemite (Zn2SiO4) and are commonly associated to red detrital clays in karstic cavities. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) with Energy Dispersive X-ray (EDX) analyses were combined in order to characterize the clay minerals and to determine the mechanism of their formation. XRD patterns on oriented and powdered clays and Fourier Transform Infrared (FTIR) spectroscopic analyses suggest that fraipontite is the major Zn clay phase (with some smectite interstrat…
The role of pedogenic overprinting in the obliteration of parent material in some polygenetic landscapes of Sicily (Italy)
Abstract Many soils older than the Holocene have experienced several changes, and possess properties that may be due to the complex effect of several stages of soil development; these soils are called polygenetic. It is still rather unclear, however, if, as time elapses, pedogenic processes tend to diverge generating different soils, or converge towards increasingly similar soils. We studied five pedons (37°60′N, 13°90′E) exposed to present weathering simultaneously since the Holocene but located on Upper Miocene or Holocene parent material. Their XRD and FTIR clay mineralogy reveal an overall homogeneity; smectites, calcite and gypsum reach the thermodynamic equilibrium, a slight undersatu…
Missions to Mars: Characterization of Mars analogue rocks for the International Space Analogue Rockstore (ISAR)
International audience; Instruments for surface missions to extraterrestrial bodies should be cross-calibrated using a common suite of relevant materials. Such work is necessary to improve instrument performance and aids in the interpretation of in-situ measurements. At the CNRS campus in Orléans, the Observatoire des Sciences de l'Univers en région Centre (OSUC) has created a collection of well-characterised rocks and minerals for testing and calibrating instruments to be flown in space missions. The characteristics of the analogue materials are documented in an accompanying online database. In view of the recent and upcoming rover missions to Mars (NASA's 2011 Mars Science Laboratory (MSL…
A new simple approach to evaluate pedogenic clay transformation in a Vertic Calcisol
The aim of this study is to characterize the pedogenic clay minerals by using simple approach: Mixing mineralogical and geochemical findings. The fine clay fractions (< 0.1 μm) of a Vertic Cambisol profile were studied by means of X-ray diffraction (XRD), infrared spectroscopy (FTIR) and cation exchange capacity (CEC). Qualitative and quantitative mineralogical compositions of the clay mixture were determined. Moreover, chemical equilibria and thermodynamic stabilities of minerals (calcite, gypsum, kaolinite, smectites and illites) were studied using results of ionic activities obtained from total concentration of various aqueous species in water extracts from soil-saturated pastes. XRD ana…
Material sources of the Roman brick-making industry in the I and II century A.D. from Regio IX, Regio XI and Alpes Cottiae
International audience; Bricks, fine pottery, ceramic gears and tiles are among the human-made objects routinely recovered in archaeological documentation. Sites associated with early civilizations can provide thousands of samples from a single excavation. They come in endless varieties according to economic and social circumstances and, as debris can last almost forever, provide important clues about the past behaviours in human societies. Any information about the provenance of ceramics is highly valuable in archaeological analysis. In the case of Roman brick-making, the provenance and manufacture of clayey materials are usually interpreted only by studying stamps imprinted on the artefac…