Tonelli G.*1, Renzulli A.1, Santi P.1, Talozzi D.2, Tramontana M.1 & Veneri F.1
1 Dipartimento di Scienze Pure e Applicate, Università degli Studi di Urbino Carlo Bo, (Italy).
2 Studio di Ingegneria e Geologia, Urbania (Italy).
Corresponding email: [email protected]
Keywords: historical centre of Urbino, bricks, raw materials.
Man used bricks for buildings for thousands of years, but the greatest breakthrough came with the invention of fired bricks (about 3.500 BC). Due to the use of mobile kilns, the Romans strongly contributed to spread the fired bricks throughout the conquered territories. The historical town of Urbino (in the list of UNESCO World Heritage since 1998) is characterized by a very widespread use of bricks in monumental walls, palaces and churches. A collection of brick samples from buildings of different historical times such as the remnants of the Roman period, the Urbino Cathedral (built in a span time between the XI and the XVIII century), the Renaissance walls and some other monuments (Mazzini, 1982; Luni, 1985; Agnati, 1999; Luni & Ermeti, 2001; Negroni, 2005) will be investigated through a comprehensive archaeometric project. Close to the town of Urbino, several raw materials suitable to make bricks, such as fine-grained clayey soils, are present and ruins of ancient furnaces since the Roman period are also recognizable (Luni, 1986). Concerning the Urbino Cathedral, the bricks are representative of numerous diachronic building phases, mainly due to the reconstructions after the seismic events of the XVII and XVIII centuries.
The aim of the present work will be the mineralogical and chemical characterization of the bricks in order to define the nature and the provenance of the raw materials employed in their manufacture. Standard thin section and powder XRD methods will be used to identify the different mineralogical assemblages and to establish the reached thermal conditions of firing, whereas major-trace elements analyses (ICP-OES-MS) will be of paramount importance for comparisons with raw materials. Physical and mechanical properties of the bricks (dry bulk density, specific gravity, total porosity and, if possible, uniaxial compressive strength) and also physical properties of the raw materials (grain size distribution and Atterberg limits) will be determined.
Finally, thermoluminescence will be used as a powerful method to date the original firing of the bricks (Martini
& Sibilia, 2001) in order to constrain a chronology of the various building periods of the architectural structures, coupled with the different pyrotechnological processes and raw materials used through the time.
Agnati U. (1999) - Urvinum Mataurense. In: Per la storia romana della provincia di Pesaro e Urbino. L’Erma di Bretschneider, 19-108.
Luni M. (1985) - Urvinum Mataurense. Dall’insediamento romano alla città medievale. In: M.L. Polichetti (ed.), “Il Palazzo di Federico da Montefeltro”. Urbino, 11-49.
Luni M. & Ermeti A.L. (2001) - Le mura di Urbino tra tardoantico e Medioevo. Edizioni all’Insegna del Giglio, 1-10.
Martini M. & Sibilia E. (2001) - Radiation in archaeometry: archaeological dating. Radiation physics and chemistry, 61(3/6), 241-246.
Mazzini F. (1982) - I mattoni e le pietre di Urbino. Argalia Editore, Urbino, 609 pp.
Negroni F. (2005) - Appunti su alcuni palazzi e case di Urbino. Accademia Raffaello, Urbino, 198 pp.
Hyperspectral sensor: a practice tool to evalute the efficacy of cleaning procedures
Vettori S.1, Verrucchi M.2, Di Benedetto F.*2, Gioventù E.3, Benvenuti M.2, Pecchioni E.2,Costagliola P.2 & Moretti S.2
1 Institute for the Conservation and Valorization of Cultural Heritage (ICVBC) - CNR, Milan, Italy.
2 Earth Sciences Department, University of Florence, Florence, Italy.
3 ISCR, Rome
Corresponding email: [email protected]
Keywords: SWIR hyperspectral investigation, sulfation of marble, Loggia di Baccio d’Agnolo.
Atmospheric agents and air pollution play a key role in the degradation of surfaces of historical buildings and monuments. One of the most diffused decay processes affecting both natural and artificial carbonate materials exposed to the urban atmosphere is the formation of sulfate-based deposits (i.e. “black crusts”). Moreover, the cleaning of exposed surfaces represents a crucial step in the restoration procedure of stone monuments and works of art. For the restorers involved in the cleaning of stone surfaces, it is crucial to know in real time the effectiveness of the adopted procedures in order to opportunely optimize and tune their interventions.
The present study focuses on the evaluation of the efficacy of different cleaning methods (i.e. laser, chemical and microbial) for the “black crusts” on marble surfaces belonging to a column of Loggia di Baccio d’Agnolo in Santa Maria del Fiore Cathedral (Florence) employing SWIR (Short Wave Infrared) hyperspectral investigation. The SWIR technique is fully non-invasive and allows to gain spectral information in both the visible (VIS) and near infrared (NIR) regions using a portable spectroradiometer (ASD Fieldspec® 3). The procedure consisted in the detection of gypsum amount still present onto the stone surfaces after partial cleaning steps. The resulting SWIR spectra were modelled through a full profile approach proposed by Suzuki et al. (2018), in order to obtain a reliable and efficient spectral decomposition and an esteem of the amount of gypsum left on the surface after each cleaning step/procedure. With a support of a dedicated software relying on the approach of Suzuki et al (2018), to be implemented in the next future, the acquisition of the spectra and the determination of the gypsum residues submitted the cleaning treatment may be in principle obtained in less than one minute for surface spots having a surface up to ~20 cm2.
In the case of the column under study, the best cleaning results were obtained for chemical cleaning and the combined use of laser and biological procedures.
Suzuki A., Vettori S., Giorgi S., Carretti E., Di Benedetto F., Dei L., Benvenuti M., Moretti S., Pecchioni E. & Costagliola P. (2018) - Laboratory study of the sulfation of carbonate stones through SWIR hyperspectral investigation. J. Cult.
Her., 32, 30-37.
Experimental and theoretical studies of magmatic processes
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hairpersonsMichael R. Carroll (Università di Camerino) Fabrizio Arzilli (Università di Manchester)
Paola Stabile (Università di Camerino)
Highly explosive basaltic eruptions: magma fragmentation induced by rapid crystallisation
Arzilli F.*1, La Spina G.1, Burton M.R.1, Polacci M.1, Le Gall N.2, Hartley M.1, Di Genova D.3, Cai B.4,Vo N.5, Bamber E.1, Nonni S.5, Atwood R.5, Llewellin E.6, Heidy M.7, Brooker R.A.7 & Lee P.2
1 School of Earth and Environmental Science, University of Manchester.
2 Department of Mechanical Engineering, University College London.
3 Institute of Non-Metallic Materials, Clausthal University of Technology.
4 School of Metallurgy and Materials, University of Birmingham.
5 Diamond Light Source, Harwell Science and Innovation Campus.
6 Department of Earth Sciences, Durham University.
7 School of Earth Sciences, University of Bristol.
Corresponding email: [email protected] Keywords: basalt, fragmentation, rapid crystallisation.
The low viscosity of basaltic magmas generally favours effusive and mildly explosive volcanic activity.
Highly explosive basaltic eruptions occur less frequently and their eruption mechanism still remains subject to debate (Szramek, 2016; Moitra et al., 2018), with implications for the significant hazard associated with explosive basaltic volcanism. Particularly, highly explosive eruptions require magma fragmentation, yet it is unclear how basaltic magmas can reach the fragmentation threshold (Papale, 1999).
In volcanic conduits, the crystallisation kinetics of an ascending magma are driven by degassing and cooling (Cashman & Blundy, 2000; La Spina et al., 2016). So far, the crystallisation kinetics of magmas have been estimated through ex situ crystallization experiments. However, this experimental approach induces underestimation of crystallization kinetics in silicate melts. The crystallization experiments reported in this study were performed in situ at Diamond Light Source (experiment EE12392 at the I12 beamline), Harwell, UK, using basalt from the 2001 Etna eruption as the starting material. We combined a bespoke high-temperature environmental cell with fast synchrotron X-ray microtomography to image the evolution of crystallization in real time. After 4 hours at sub-liquidus conditions (1170 °C and 1150 °C) the system was perturbed through a rapid cooling (0.4 °C/s), inducing a sudden increase of undercooling. Our study reports the first in situ observation of exceptionally rapid plagioclase crystallisation in trachybasaltic magmas. We combine these constraints on crystal kinetics and viscosity evolution with a numerical conduit model to show that exceptionally rapid syn-eruptive crystallisation is the fundamental process required to trigger basaltic magma fragmentation under high strain rates.
Cashman K. & Blundy J. (2000) - Degassing and crystallisation of ascending andesite and dacite. Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 358, 1487-1513.
La Spina G., Burton M., Vitturi M.D.M. & Arzilli F. (2016) - Role of syn-eruptive plagioclase disequilibrium crystallisation in basaltic magma ascent dynamics. Nature communications, 7, 13402.
Moitra P., Gonnermann H.M., Houghton B.F. & Tiwary C.S. (2018) - Fragmentation and Plinian eruption of crystallizing basaltic magma. Earth and Planetary Science Letters, 500, 97-104.
Papale P. (1999) - Strain-induced magma fragmentation in explosive eruptions. Nature, 397, 425.
Szramek, L.A. 2016. Mafic Plinian eruptions: Is fast ascent required? Journal of Geophysical Research: Solid Earth, 121, 7119-7136.
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