We recently showed that highly ordered graphitic films can be formed on specific mineral surfaces during metamorphism of organic-rich sediments (van Zuilen et al., 2012). This mineral-template-induced process may be of interest for the artificial synthesis of sp2-bonded carbon structures and can possibly lead to innovations in carbon-based nanomaterials such as 3D-fiber-lattice networks, meso-porous thick films, thin graphite films, and carbon-microtube rings. Based on our experience with metamorphosed carbonaceous matter and fluid-deposited carbon in high-grade metamorphic terrains (Lepland et al., 2011) we will confidently develop a rigorous analytical program on naturally occurring carbonaceous solids. The combined use of Raman spectroscopy, FIB combined with TEM-EELS, and synchrotron-based techniques such as µXANES, will provide a powerful innovative approach for the study of geologic nano-materials. For more details, see Mark van Zuilen.
Various types of sp3-bonded carbon (i.e., 3C diamond, 2H lonsdaleite and similar 2nH hexagonal polytypes), formed under ultrahigh-pressure conditions, were for the first time described these last years in natural samples whose formation is still enigmatic (e.g. Godard et al., 2011). We will thus carry on the study of the natural forms of disordered sp3-bonded carbon in ultrahigh-pressure rocks, with the aim of characterizing these forms, understanding how they form and what they imply for the rheology of rocks formed at extreme depths. The characterization of the Popigaï “lonsdaleite” will be pursued. New samples will be investigated, particularly micro-diamonds preserved as inclusions in chromite from ultra-deep garnet peridotites of China and Northern Urals. A preliminary study shows that these micro-diamonds display the crystal shapes of hexagonal polytypes but show the typical Raman spectrum of 3C diamond, so that they could have been lonsdaleite transformed into 3C diamond. For more details, see Gaston Godard.