Cathodoluminescence is the phenomenon of photon emission of a solid surface excited by an electron beam. In the cold cathode equipment, the electron beam is produced by the electrical discharge between two metal electrodes instead of the incandescence of a tungsten filament as in the SEM and hot cathodoluminescence.
Cathodoluminescence in rock minerals depends on crystallographic defects and dislocations and trace element concentration. In particular, some elements activate luminescence whereas others quench it. Depending on the type of mineral and the activator/quencher quantitative ratio different colours and/or intensity of brightness may result.
The Laboratory
The cold cathodoluminescence laboratory is hosted at the Torino Territorial Unit of IGG
Instruments
The laboratory equipment consists of:
- CITL 8200 mk3 cathodoluminescence microscope stage, combined with an Olympus BH2 polarization light microscope.
- Olympus DP 74 20.7 Mpx high-sensitivity camera, with dedicated Olympus Stream software that allows the acquisition of digital images in various formats.
Staff and Contacts
The staff of the cold cathodoluminescence laboratory is composed of:
- Luca Barale (Ricercatore IGG – Responsabile laboratorio)
- Luca Martire (Professore Associato, Università di Torino, DST – Responsabile laboratorio)
Contacts:
- Luca Barale (IGG Researcher – Laboratory Manager)
- Luca Martire (Associate Professor, University of Turin, DST – Laboratory Manager)
Methods and Applications
Cold cathodoluminescence has numerous applications in the field of earth sciences, particularly in the field of sedimentary geology and in the study of hydrothermal systems.
- Reconstruction of diagenetic/hydrothermal sequences: Variations in geochemical conditions during the precipitation of diagenetic/hydrothermal minerals result in more or less complex zoning, which can be correlated between samples from different sectors. CL can also highlight specific structures, both within individual crystals and within the rock (dissolution surfaces, micro-brecciation), which are difficult to detect with other methods in the absence of significant textural or compositional variations.
- studies on the provenance of arenites: the CL characteristics of many of the main constituents of arenite grains (e.g., quartz, feldspars) allow us to distinguish between minerals of volcanic, plutonic or metamorphic origin.
Cathodoluminescence studies can be performed on conventional thin sections, strictly uncoated (preferably polished), and on rock slabs up to 15 mm thick (and with a maximum size of 6 x 4 cm). No preliminary sample preparation is necessary.
Cathodoluminescence allows an easy distinction between phosphatic (blue) and ferruginous (black) accretions.
Scientific Projects and Interests
The cold cathodoluminescence apparatus, active at the Turin site since 1992, has been used in numerous scientific projects, such as, for example:
- study of fossil hydrothermal systems in the Mesozoic carbonate successions of the Alpine Tethys;
- study of methane-derived authigenic carbonates in the Tertiary successions of the Piedmont Tertiary Basin;
- characterization of stone artefacts of archaeological/cultural heritage interest (e.g., lapis lazuli objects), as part of studies on the provenance of materials.
Publications
- Incerpi N., Martire L., Bernasconi S., Manatschal G., Gerdes A. (2018) Silica-rich septarian concretions in biogenic silica-poor sediments: a marker of hydrothermal activity at fossil hyper-extended rifted margins (Err nappe, Switzerland). Sedimentary Geology, 378, 19-33.
- Barale L., Bertok C., d’Atri A., Martire L., Piana F. (2017) Stratigraphy, sedimentology and syndepositional tectonics of the Jurassic–Cretaceous succession at the transition between Provençal and Dauphinois domains (Maritime Alps, NW Italy). Rivista Italiana di Paleontologia e Stratigrafia, 123, 3, 355-378.
- Incerpi N., Martire L., Manatschal G., Bernasconi S. (2017) Evidence of hydrothermal fluid flow in a hyperextended rifted margin: the case study of the Err nappe (SE Switzerland). Swiss Journal of Geosciences, 110, 439-456.
- Barale L., Bertok C., Salih Talabani N., d’Atri A., Martire L., Piana F. Préat A. (2016) Very hot, very shallow hydrothermal dolomitization: an example from the Maritime Alps (NW Italy–SE France). Sedimentology, 63, 7, 2037–2065.
- Martire L., Bertok C., d’Atri A., Perotti E., Piana F. (2014) Selective dolomitization by syntaxial overgrowth around detrital dolomite nuclei: a case from the Jurassic of the Ligurian Briançonnais (Ligurian Alps). Journal of Sedimentary Research, 84, 40–50.
- Barale L., d’Atri A., Martire L. (2013) The role of microbial activity in the generation of Lower Cretaceous mixed Fe-oxide–phosphate ooids from the Provençal Domain, French Maritime Alps. Journal of Sedimentary Research, 83, 196–206.
- Perotti E., Bertok C., d’Atri A., Martire L.., Piana F., Catanzariti R. (2012) A tectonically-induced Eocene sedimentary mélange in the West Ligurian Alps, Italy. Tectonophysics, 568-569, 200-214.
- Bertok C., Martire L., Perotti E., d’Atri A. & Piana F. (2012) Kilometre-scale palaeoescarpments as evidence for Cretaceous synsedimentary tectonics in the External Briançonnais Domain (Ligurian Alps, Italy). Sedimentary Geology, 251-252, 58-75.
- Natalicchio M., Birgel d., Dela Pierre f., Martire L., Clari P., Spötl C., Peckmann J. (2012) Polyphasic carbonate precipitation in the shallow subsurface: Insights from microbially-formed authigenic carbonate beds in upper Miocene sediments of the Tertiary Piedmont Basin (NW Italy). Palaeogeography, Palaeoclimatology, Palaeoecology, 329-330, 158-172.
- Bertok C., Martire L., Perotti E., d’Atri A., Piana F. (2011) Middle-Late Jurassic syndepositional tectonics recorded in the Ligurian Brianconnais succession (Marguareis–Mongioie area, Ligurian Alps, NW Italy). Swiss Journal of Geosciences, 104, 237-255.
- Dela Pierre F., Martire L., Natalicchio M., Clari P., Petrea C. (2010) Authigenic carbonates in Upper Miocene sediments of the Tertiary Piedmont Basin (NW Italy): Vestiges of an ancient gas hydrate stability zone?
- GSA Bulletin, 122 (7-8), 994-1010.
- Martire L., Natalicchio M., Petrea C., Cavagna S., Clari P., & Dela Pierre F. (2010) Petrographic evidence of the past occurrence of gas hydrates in the Tertiary Piedmont Basin (NW Italy). GeoMar-Lett., 30, 461-476.
- Clari P., Dela Pierre F., Martire L., Cavagna S. (2009) The Cenozoic CH4-derived carbonates of Monferrato (NW Italy): A solid evidence of fluid circulation in the sedimentary column. Marine Geology, 265, 167-184.
- Lo Giudice A., Re A., Calusi S., Giuntini L., Massi M., Olivero P., Pratesi G., Albonico M., Conz E. (2009) Multitechnique characterization of lapis lazuli for provenance study. Analytical and Bioanalytical Chemistry, 395, 2211-2217.
- Perello P., Delle Piane L., Piana F., Stella F., Damiano A. (2004) Brittle post-metamorphic tectonics in the Gran Paradiso Massif (north-western Italian Alps). Geodinamica Acta, 17, 71-90.
- Clari P., Cavagna S., Martire L. & Hunziker J. (2004) – A Miocene mud volcano and its plumbing system: a chaotic complex revisited (Monferrato, NW Italy). Jour.Sed.Res., 74, 662-676.