334 results on '"Andrea Dini"'
Search Results
2. [Deep geothermal and energy: electricity, geothermal lithium, critical raw materials]
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Paolo Cerutti, Andrea Dini, and Emanuele Emani
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Deep geothermal ,geothermal lithium ,critical raw materials ,Geology ,QE1-996.5 - Abstract
[Article in Italian] Geotermia profonda ed energia: elettricità, litio geotermico, materie prime critiche
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- 2024
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3. Prego! An Invitation to Italian Graziana Lazzarino Maria Cristina Peccianti Andrea Dini
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Pausini, Cristina
- Published
- 2009
4. Approaches to Teaching Petrarch’s Canzoniere and the Petrarchan Tradition ed. by Christopher Kleinhenz and Andrea Dini (review)
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Hiltzik, Andrew
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- 2016
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5. Prego! An Invitation to Italian Graziana Lazzarino Maria Cristina Peccianti Janice M. Aski Andrea Dini Pamela Marcantonio Loredana Anderson-Tirro Giuseppe Faustini Maria Mann
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Arthur, Gabriella Colussi
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- 2004
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6. Geology of Montecastelli Pisano (inner Northern Apennines, Italy): normal and transfer fault zones affecting a dismantled ophiolite bearing orogenic wedge
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Andrea Brogi, Domenico Liotta, Andrea Dini, and Andrea Rielli
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Transfer faults ,superimposed extensional structures ,serpentinite ,Ligurian ophiolite ,extensional tectonics ,Northern Apennines ,Maps ,G3180-9980 - Abstract
ABSTRACTWe present the geological map (1:10.000) of the Montecastelli Pisano area, where (i) the relationships between Neogene-Quaternary transfer and normal faults have been carefully mapped (Sheet 1), and (ii) the mantle sequence of the Ligurian Ocean has been analysed (Sheet 2). Fault analyses allowed to define: (i) NE-trending fault system (left-lateral strike- to oblique-slip faults) belonging to a transfer shear zone; and (ii) NW-trending normal to oblique-slip faults. Their evolution is framed in the extensional tectonics affecting the Northern Apennines since Early-Middle Miocene. The ophiolite complex is constituted by serpentinized spinelharzburgite with minor serpentinized dunite channels cut by gabbro dykes. A km-scale cataclastic zone cut the mantle section, locally hosting Cu-Fe mineralization. The goal of this work is to present the distribution of the main fractures affecting an area where the occurrence of ophiolite can favor the success of the CO2 reinjection project.
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- 2023
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7. Approaches to Teaching Petrarch’s Canzoniere and the Petrarchan Tradition ed. by Christopher Kleinhenz and Andrea Dini
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Andrew Hiltzik
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History ,General Medicine ,Theology ,Classics - Published
- 2016
8. Graziana Lazzarino, Maria Cristina Peccianti, Janice M. Aski, and Andrea Dini (with contributions by Pamela Marcantonio, Loredana Anderson-Tirro, Giuseppe Faustini, and Maria Mann). Prego! An Invitation to Italian
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Arthur, Gabriella Colussi
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Prego! An Invitation to Italian, 6th ed. (Book) -- Lazzarino, Graziana -- Peccianti, Maria Cristina -- Aski, Janice M. -- Dini, Andrea ,Books -- Book reviews ,Languages and linguistics - Abstract
Graziana Lazzarino, Maria Cristina Peccianti, Janice M. Aski, and Andrea Dini (with contributions by Pamela Marcantonio, Loredana Anderson-Tirro, Giuseppe Faustini, and Maria Mann). Prego! An Invitation to Italian. Sixth Edition. [...]
- Published
- 2004
9. The Ophiolite-Hosted Cu-Zn VMS Deposits of Tuscany (Italy)
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Andrea Dini, Andrea Rielli, Paolo Di Giuseppe, Giovanni Ruggieri, and Chiara Boschi
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VMS deposits ,ophiolites ,slow spreading ridge ,cataclasite ,bornite ,orebodies ,Mineralogy ,QE351-399.2 - Abstract
Several Jurassic, ophiolite-hosted Cu-Zn VMS deposits occur in Tuscany. They are hosted by tectonic units of oceanic affinity (Ligurian Units), such as the well-known deposits of nearby Liguria. Industrial production was small and definitively ceased in the 1960s. Locally, massive ore (chalcopyrite-bornite-chalcocite) with an exceptionally high grade was found. The Montecatini Val di Cecina mine exploited the largest “bonanza” and, for few decades in the 19th century, became one of the most profitable copper mines in Europe. This study provides an updated review of these deposits. Tuscan Cu-Zn VMSs mostly occur in proximity of the contact between the serpentinite-gabbro basement and the overlying basalts. Chalcopyrite-pyrite stockworks occur in serpentinite-gabbro cut by dolerite dykes, while the largest massive sulphide bodies are hosted by polymictic-monomictic breccias at the base of pillow basalts. Early chalcopyrite ores were mechanically–chemically reworked and upgraded to bornite-rich nodular ore embedded in a chlorite, calcic amphibole, Fe-rich serpentine, quartz, andradite, ilvaite, and xonotlite assemblage. This bornite-rich ore contains substantial amount of sphalerite and pyrite and ubiquitous grains of clausthalite, hessite, tellurium, and gold. They represent a prime example of the sub-seafloor portion of a hybrid mafic-ultramafic oceanic hydrothermal system formed in an OCC along the slow spreading ridge of the Jurassic Piedmont-Ligurian Ocean. The peculiar mineralogical–textural character of the bornite-rich ore was driven by an interface coupled dissolution–precipitation process mediated by fluids.
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- 2024
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10. Three-dimensional muon imaging of cavities inside the Temperino mine (Italy)
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Diletta Borselli, Tommaso Beni, Lorenzo Bonechi, Massimo Bongi, Debora Brocchini, Nicola Casagli, Roberto Ciaranfi, Luigi Cimmino, Vitaliano Ciulli, Raffaello D’Alessandro, Andrea Dini, Catalin Frosin, Giovanni Gigli, Sandro Gonzi, Silvia Guideri, Luca Lombardi, Massimiliano Nocentini, and Giulio Saracino
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Medicine ,Science - Abstract
Abstract Muon radiography (muography) is an imaging technique based on atmospheric muon absorption in matter that allows to obtain two and three-dimensional images of internal details of hidden objects or structures. The technique relies on atmospheric muon flux measurements performed around and underneath the object under examination. It is a non-invasive and passive technique and thus can be thought of as a valid alternative to common prospecting techniques used in archaeological, geological and civil security fields. This paper describes muon radiography measurements, in the context of archaeological and geological studies carried out at the Temperino mine (LI, Tuscany, Italy), for the search and three-dimensional visualisation of cavities. This mine has been exploited since Etruscan times until recently (1973), and is now an active tourist attraction with public access to the tunnels. Apart from the archaeological interest, the importance of mapping the cavities within this mine lies in identifying the areas where the extraction ores were found and also in the safety issues arising from the tourist presence inside the mine. The three-dimensional imaging is achieved with two different algorithms: one involving a triangulation of two or more measurements at different locations; the other, an innovative technique used here for the first time, is based on the back-projections of reconstructed muon tracks. The latter requires only a single muographic data tacking and is to be preferred in applications where more than one site location can be difficult to access. Finally the quality of the three-dimensional muographic imaging was evaluated by comparing the results with the laser scan profiles obtained for some known cavities within the Temperino mine.
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- 2022
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11. Approaches to Teaching Petrarch’s ‘Canzoniere’ and the Petrarchan Tradition ed. by Christopher Kleinhenz and Andrea Dini (review)
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Stoessel, Jason
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- 2017
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12. Prego! An Invitation to Italian 7th ed. by LAZZARINO, GRAZIANA, MARIA CRISTINA PECCIANTI, & ANDREA DINI. Workbook to Accompany Prego! An Invitation to Italian . 7th ed. by LAZZARINO, GRAZIANA, & ANDREA DINI
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Cristina Pausini
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Linguistics and Language ,Workbook ,media_common.quotation_subject ,Art ,Humanities ,Language and Linguistics ,media_common - Abstract
The article reviews the books "Prego! An Invitation to Italian," 7th ed., by Graziana Lazzarino, Maria Cristina Peccianti and Andrea Dini and "Workbook to Accompany Prego! An Invitation to Italian," 7th ed., by Graziana Lazzarino and Andrea Dini.
- Published
- 2009
13. Timescale of a magmatic-hydrothermal system revealed by 40Ar–39Ar geochronology: the Mio-Pliocene Campiglia Marittima system (Tuscany, Italy)
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Gianfranco Di Vincenzo, Simone Vezzoni, Andrea Dini, and Sergio Rocchi
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Medicine ,Science - Abstract
Abstract Petrology and timing of magmatic-hydrothermal systems and the linkage between plutonic and volcanic domains are central topics in geosciences, because of broad implications for natural hazards and exploitation of natural resources. We investigated by the 40Ar–39Ar method the timescale of a well-characterized natural example, the Mio-Pliocene Campiglia Marittima magmatic-hydrothermal system (Tuscany, Italy). 40Ar–39Ar data from pristine and homogeneous trioctahedral micas and sanidine from the plutonic-hydrothermal-subvolcanic-volcanic sequence (from the Botro ai Marmi Granite to the San Vincenzo Rhyolite) record crystallization ages and define a temporal sequence lasting 973 ± 43 ka, starting from 5.409 ± 0.043 Ma. K-feldspar from mafic and felsic porphyries, unlike micas, are affected by submillimetre, micropore laden, alteration domains consisting of secondary K-feldspar and albite, and yielded staircase-shaped age spectra, compatible with a ternary mixing. Results document that the San Vincenzo Rhyolite consists of two diachronous batches, the first emplaced at 5.0024 ± 0.0062 Ma, closely following emplacement of mafic porphyries, the second at 4.4359 ± 0.0045 Ma. Bulk of hydrothermal deposits, consisting of skarns and associated Zn–Pb(-Ag) mineralization predating Fe–Cu ore, formed within the first ~ 400-ka lifetime of the whole sequence and was closely followed by the first eruption which should have run out most of the ore-forming potential of the system.
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- 2022
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14. Approaches to Teaching Petrarch’s ‘Canzoniere’ and the Petrarchan Tradition ed. by Christopher Kleinhenz and Andrea Dini
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Stoessel, Jason, primary
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- 2016
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15. Fabian Alfie and Andrea Dini, eds., “Accessus ad auctores”: Studies in Honor of Christopher Kleinhenz. (Medieval and Renaissance Texts and Studies 397.) Tempe: Arizona Center for Medieval and Renaissance Studies, 2011. Pp. xxii, 506; black-and-white plates, black-and-white figures, and tables. $75. ISBN: 9780866984454.
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Botterill, Steven, primary
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- 2014
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16. Approaches to Teaching Petrarch’s ‘Canzoniere’ and the Petrarchan Tradition ed. by Christopher Kleinhenz and Andrea Dini
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Jason Stoessel
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Microbiology (medical) ,media_common.quotation_subject ,Immunology ,Immunology and Allergy ,Art ,Theology ,Classics ,media_common - Published
- 2016
17. Prego! An Invitation to Italian 7th ed. by LAZZARINO, GRAZIANA, MARIA CRISTINA PECCIANTI, & ANDREA DINI. Workbook to Accompany Prego! An Invitation to Italian . 7th ed. by LAZZARINO, GRAZIANA, & ANDREA DINI.
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PAUSINI, CRISTINA, primary
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- 2009
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18. Campiglia Marittima Skarn (Tuscany): A Challenging Example for the Evolution of Skarn-Forming Models
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Simone Vezzoni, Sergio Rocchi, and Andrea Dini
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Campiglia Marittima ,ore deposit ,skarn ,Mineralogy ,QE351-399.2 - Abstract
Campiglia Marittima (hereafter Campiglia) has a long record of attracting interest on its ore deposits that have been intermittently exploited from the Copper Age to the late XX century. Since the XIX century, Campiglia has been a key locality for the debate on skarn-forming processes due to the presence of mining activities ensuring access to ever new rock exposures. The pioneering study of vom Rath and the comparison with attractive chemical model (e.g., Korzhinskii’s theory) in the XX century made Campiglia a “classic” example of skarn ore deposit, from the causative intrusion to the marble host rock. In recent years, detailed field investigations integrated by petrographic, geochemical, and isotopic analyses revealed a more complex and stimulating geological history. The Campiglia skarn was later intruded by mafic magma causing textural reworking and chemical redistribution as well as the reverse telescoping process with Fe-Cu sulfides overprinting previously formed Pb-Zn ore. This work aims to trace the evolution of the scientific thinking on the Campiglia ore deposit by comparison with existing skarn-forming models and, ultimately, shows that the current skarn-forming model(s) cannot fully explain the textural and geochemical features of the Campiglia skarn.
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- 2023
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19. Lithium Occurrence in Italy—An Overview
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Andrea Dini, Pierfranco Lattanzi, Giovanni Ruggieri, and Eugenio Trumpy
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lithium ,Italy ,geothermal fluids ,Mineralogy ,QE351-399.2 - Abstract
Italy has no record of Li production, even though it is well known for its outstanding Li mineral specimens from the Elba Island pegmatites. Because of the current geopolitical situation, the opportunity for a systematic appraisal of resources is evident. Most European Li production comes from deposits associated with Late Paleozoic magmatic rocks. In Italy, such rocks occur extensively in Sardinia and Calabria, but their potential for Li is unknown, and deserves a more systematic exploration. Also of potential interest are the Permo–Triassic spodumene pegmatites in the Austroalpine units of the Central Alps. The Tertiary pegmatites (Elba Island and Central Alps) contain Li minerals, but do not appear large enough to warrant bulk mining. However, we notice that Tertiary–Quaternary magmatic rocks of the Tuscan and Roman magmatic provinces have systematically higher Li contents than those recorded in normal arc igneous rocks worldwide. Specifically, Tuscan granites contain up to 350 μg/g Li, mostly hosted by biotite (up to 4000 μg/g Li); the Capo Bianco aplite (Elba Island) contains up to 1000 μg/g. There are other small Li occurrences associated with Mn deposits and metabauxites, and there is a hypothetical potential for sediment-hosted deposits in the post-orogenic Lower Permian Alpine basins. However, the most promising potential seems to be associated with subsurface fluids. High-enthalpy fluids in geothermal fields may contain up to 480 mg/L Li. Lower-temperature thermal waters may also contain significant Li (>10 mg/L). Moreover, a visionary, but not impossible, perspective may consider a deep injection of water to interact with, and extract Li from, magmatic rocks.
- Published
- 2022
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20. Dutrowite, Na(Fe2+2.5Ti0.5)Al6(Si6O18)(BO3)3(OH)3O, a new mineral from the Apuan Alps (Tuscany, Italy): the first member of the tourmaline supergroup with Ti as a species-forming chemical constituent
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Cristian Biagioni, Ferdinando Bosi, Daniela Mauro, Henrik Skogby, Andrea Dini, and Federica Zaccarini
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The new tourmaline supergroup mineral dutrowite, Na(Fe2.52+Ti0.5)Al6(Si6O18)(BO3)3(OH)3O, has been discovered in an outcrop of a Permian metarhyolite near the hamlet of Fornovolasco, Apuan Alps, Tuscany, Italy. It occurs as chemically homogeneous domains, up to 0.5 mm, brown in colour, with a light-brown streak and a vitreous lustre, within anhedral to subhedral prismatic crystals, up to 1 mm in size, closely associated with Fe-rich oxy-dravite. Dutrowite is trigonal, space group R3m, with a=15.9864(8), c=7.2187(4) Å, V=1597.68(18) Å3, and Z=3. The crystal structure was refined to R1=0.0257 for 1095 unique reflections with Fo>4σ (Fo) and 94 refined parameters. Electron microprobe analysis, coupled with Mössbauer spectroscopy, resulted in the empirical structural formula X(Na0.81Ca0.20K0.01)Σ1.02 Y(Fe1.252+Mg0.76Ti0.56Al0.42)Σ3.00 Z(Al4.71Fe0.273+V0.023+Mg0.82Fe0.182+)Σ6.00 T[(Si5.82Al0.18)Σ6.00O18] (BO3)3O(3)(OH)3O(1)[O0.59(OH)0.41]Σ1.00, which was recast in the empirical ordered formula, required for classification purposes: X(Na0.81Ca0.20K0.01)Σ1.02 Y(Fe1.432+Mg1.00Ti0.56)Σ3.00 Z(Al5.13Fe0.273+V0.023+Mg0.58)Σ6.00 T[(Si5.82Al0.18)Σ6.00O18] (BO3)3V(OH)3 W[O0.59(OH)0.41]Σ1.00. Dutrowite is an oxy-species belonging to the alkali group of the tourmaline supergroup. Titanium is hosted in octahedral coordination, and its incorporation is probably due to the substitution 2Al3+ = Ti4+ + (Fe,Mg)2+. Its occurrence seems to be related to late-stage high-T/low-P replacement of “biotite” during the late-magmatic/hydrothermal evolution of the Permian metarhyolite.
- Published
- 2023
21. Deep Electrical Resistivity Tomography as a mineral exploration tool: the Calamita distal Fe-skarn, Elba Island (Italy)
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Damian Braize, Julien Sfalcin, Matteo Lupi, Kalin Kouzmanov, Andrea Dini, and Gianfranco Morelli
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To face the growing demand for raw materials, the discovery of new mineral deposits is essential for the future. Geophysical methods, and in particular electrical and electromagnetic tools, have an important role in mineral exploration. Recently, new technological developments made possible targetting deeper ore bodies and large areas with logistical challenges. We use the Deep Electrical Resistivity Tomography (DERT) method to investigate its application in mineral exploration. In particular, we use the Fullwaver technology developed by IRIS Instruments to study the full 3D resistive structure of the Calamita distal Fe-skarn deposit, Elba Island, Italy. This innovative hardware allows a full 3D deployment of autonomous and cable-less receivers and contrasts with traditional resistivity methods by its easy set-up and applicability in difficult contexts.In November 2022, a 3D DERT survey has been carried out to investigate the Calamita deposit, consisting of massive magnetite-hematite ore bodies hosted in marbles overlaying micaschists of Tuscan Units. Skarn mineralogy/geochemistry and fluid inclusion characteristics suggest a magmatic source for the mineralizing fluids. 148 current injections have been performed on 48 receivers over an area of 2km² with the aim to reach exploration depths ranging from 600 m to 700 m. Geophysical data were combined with a high-resolution 3D Digital Elevation Model acquired by standard and thermal drone imagery.The 3D inverted resistivity and induced polarization models match with the surface geology and shallow exploration drill hole data and highlight the architecture of Calamita deposit. Strong resistivity contrasts reveal the presence of sub-vertical conductive and chargeable pipes connecting the different skarn bodies at depth, interpreted to represent the paleo-hydrothermal upflow zones. The pipes point towards the inferred cupola of a magmatic intrusion that potentially triggered the formation of the ore deposit. High chargeability anomalies suggest the presence of hidden massive ore bodies and disseminated mineralisation on the flanks of the system.DERT has the potential to investigate and explore mineral deposits in full 3D, with high sensitivity, and in logistically complex settings.
- Published
- 2023
22. Three-dimensional localization of Radon source conduits inside the Temperino mine (Tuscany-Italy) with the muon radiography technique
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Diletta Borselli, Tommaso Beni, Lorenzo Bonechi, Massimo Bongi, Debora Brocchini, Nicola Casagli, Roberto Ciaranfi, Vitaliano Ciulli, Raffaello D'Alessandro, Andrea Dini, Catalin Frosin, Giovanni Gigli, Sandro Gonzi, Silvia Guideri, Luca Lombardi, Andrea Paccagnella, and Simone Vezzoni
- Abstract
Muon radiography, or muography, is a non-invasive technique allowing imaging of the interior of large structures (target) thanks to the study of the absorption of atmospheric muons in materials. The muons absorption effect depends not only on the thickness, but also on the density of the target. Careful comparisons of the muographic results with simulations taking into account a precise description of the target's geometry, allow estimating the two dimensional distribution of the average density of the structure under study as seen from the measurement point of view. In this presentation an application in the geological field for the research and localization of low density anomalies attributable to cavities inside an abandoned mine will be shown. The aim of the study is to identify and locate areas that might be responsible for the production of anomalous concentrations of radon gas inside underground mining sites used for touristic itineraries. Radon is a natural radioactive gas that exposes tourists to ionizing radiation. Radon decay products are the second cause of lung cancer after smoking. It is important therefore to understand where the radon gas comes from before moving through the different galleries. The case study is the Temperino mine near Campiglia Marittima (LI-Italy). Here, the mining activity ended in 1980 and it was primarily focused on the extraction of copper, silver lead and zinc minerals. The area to be explored with muon radiography is part of an area dating back to the Etruscan period that has not yet been completely mapped and that is located above the tourist path of the Temperino mine at a depth of about 40 m from the surface of the hill above. Any nearby cavity could represent a prime conduit that brings radon gas into the tourist trail. The identification and localization in space of these ancient excavations is also interesting from a geological and archaeological point of view. The detector employed for the muographic measurements reported in this presentation, designed in Florence by the National Institute of Nuclear Physics (INFN) and the Department of Physics and Astronomy, is called MIMA (Muon Imaging for Mining and Archaeology) and has cubic shape and approximate dimensions of (50x50x50) cm3. MIMA is equipped with a special protective aluminum mechanism that allows its altazimuth orientation.
- Published
- 2023
23. Transmission-Based Muography for Ore Bodies Prospecting: A Case Study from a Skarn Complex in Italy
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Tommaso Beni, Diletta Borselli, Lorenzo Bonechi, Massimo Bongi, Debora Brocchini, Roberto Ciaranfi, Luigi Cimmino, Vitaliano Ciulli, Raffaello D’Alessandro, Andrea Dini, Catalin Frosin, Giovanni Gigli, Sandro Gonzi, Silvia Guideri, Luca Lombardi, Massimiliano Nocentini, Giulio Saracino, Nicola Casagli, Beni, T., Borselli, D., Bonechi, L., Bongi, M., Brocchini, D., Ciaranfi, R., Cimmino, L., Ciulli, V., D'Alessandro, R., Dini, A., Frosin, C., Gigli, G., Gonzi, S., Guideri, S., Lombardi, L., Nocentini, M., Saracino, G., and Casagli, N.
- Subjects
General Environmental Science - Abstract
Transmission-based muography (TM) is an innovative imaging technique based on the measurement and analysis of the cosmic ray muons flux attenuation within the target under investigation. This technique allows imaging inner-body density differences and has successfully been applied in a wide range of research fields: geology, archaeology, engineering geology and civil engineering. The aim of this study is to show the reliability of TM as an innovative, noninvasive geophysical method for ore body prospecting and other mining related studies. The measurements were carried out at the Temperino mine in the San Silvestro Archaeological and Mining Park (Campiglia Marittima, Italy), where several magmatic and metasomatic geological units are embodied. Among them, a Cu–Fe–Zn–Pb(–Ag) sulfide skarn complex primarily composed by hedenbergite and ilvaite minerals. Using the acquired muon imaging data obtained with the MIMA (Muon Imaging for Mining and Archaeology) detector prototype (cubic detector of 0.5 × 0.5 × 0.5 m3), the presence of a high-density vein inside the skarn body within the rock volume above the muon detector was identified, localized and interpreted. Applying a back-projection algorithm to the obtained 2D transmission map made it possible to estimate and visualize as point cloud data, in a 2D or 3D environment, the identified high-density body and its relative distance from the detector. The results of this study highlight the potential of muography as a support tool to other geophysical methods in the field of mining exploration.
- Published
- 2023
24. Fractures, fluid flow and inherited structures in geothermal systems: inputs from the Fe-ore deposits of eastern Elba Island (Northern Apennines, Italy)
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Martina Zucchi, Andrea Brogi, Domenico Liotta, Alfredo Caggianelli, Andrea Dini, Gennaro Ventruti, Giovanni Ruggieri, and Paola Francesca Matera
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Geology - Abstract
Geothermal systems in terrains affected by polyphase deformation have reservoirs with a 3D geometry that is always difficult to predict. In this paper we describe a fossil exhumed geothermal system exposed in eastern Elba Island that developed in a polyphase folded and faulted setting, which can help us to understand how geothermal fluids circulate in geological bodies with inherited structures. Geothermal circulation at Elba allowed the deposition of Fe-ore deposits (haematite/magnetite and pyrite) and altered rock volumes, which represent tracers of the palaeo-fluid flow. Normal and oblique-slip faults dissected a polyphase folded metasiliciclastic succession and produced a secondary permeability in the range of 5 × 10−13 to 5 × 10−16 m2. From the permeable fault zones acting as feeder conduits, geothermal fluids permeated the hydraulically connected metasiliciclastic rock bodies previously deformed by two generations of folds. Geothermal fluids followed the already defined geometry, thus giving rise to apparent folded mineralized levels. Fluid migration into the metasiliciclastic rocks was possible due to their chemical aggression, which favoured the dissolution and reprecipitation of quartz, and Fe-oxide and sulphide deposition. Renewed fluids maintained their chemical properties (pH value and temperature, mostly). This conclusion provides inputs for reconstructing geothermal conceptual models and evaluating the geothermal potentiality of exploitable areas developing in similar geological settings.
- Published
- 2022
25. Permian Hydrothermal Alteration Preserved in Polymetamorphic Basement and Constraints for Ore-genesis (Alpi Apuane, Italy)
- Author
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Simone Vezzoni, Diego Pieruccioni, Yuri Galanti, Cristian Biagioni, and Andrea Dini
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basement ,Permian magmatism ,hydrothermal alteration ,ore genesis ,Alpi Apuane ,Geology ,QE1-996.5 - Abstract
The reconstruction of the polymetamorphic history of basement rocks in orogens is crucial for deciphering past geodynamic evolution. However, the current petrographic features are usually interpreted as the results of the metamorphic recrystallization of primary sedimentary and/or magmatic features. In contrast, metamorphic rocks derived by protoliths affected by pre-metamorphic hydrothermal alterations are rarely recognized. This work reports textural, mineralogical and geochemical data of metasedimentary and metaigneous rocks from the Paleozoic succession of the Sant’Anna tectonic window (Alpi Apuane, Tuscany, Italy). These rocks were recrystallized and reworked during the Alpine tectono-metamorphic event, but the bulk composition and some refractory minerals (e.g., tourmaline) are largely preserved. Our data show that the Paleozoic rocks from the Alpi Apuane were locally altered by hydrothermal fluids prior to Alpine metamorphism, and that the Permian magmatic cycle was likely responsible for this hydrothermal alteration. Finally, the Ishikawa Alteration Index, initially developed for magmatic rocks, was applied to metasedimentary rocks, providing a useful geochemical tool for unravelling the hydrothermal history of Paleozoic rocks, as well as a potential guide to the localization of hidden ore deposits in metamorphic terranes.
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- 2020
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26. HFSE‐REE Transfer Mechanisms During Metasomatism of a Late Miocene Peraluminous Granite Intruding a Carbonate Host (Campiglia Marittima, Tuscany)
- Author
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Gabriele Paoli, Andrea Dini, Maurizio Petrelli, and Sergio Rocchi
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metamorphic contact aureole ,metasomatism ,hfse/ree‐bearing minerals ,hfse/ree mobility ,ree‐rich metasomatic ca‐silicates ,Mineralogy ,QE351-399.2 - Abstract
The different generations of calc‐silicate assemblages formed during sequential metasomatic events make the Campiglia Marittima magmatic−hydrothermal system a prominent case study to investigate the mobility of rare earth element (REE) and other trace elements. These mineralogical assemblages also provide information about the nature and source of metasomatizing fluids. Petrographic and geochemical investigations of granite, endoskarn, and exoskarn bodies provide evidence for the contribution of metasomatizing fluids from an external source. The granitic pluton underwent intense metasomatism during post‐magmatic fluid−rock interaction processes. The system was initially affected by a metasomatic event characterized by circulation of K‐rich and Ca(‐Mg)‐rich fluids. A potassic metasomatic event led to the complete replacement of magmatic biotite, plagioclase, and ilmenite, promoting major element mobilization and crystallization of K‐feldspar, phlogopite, chlorite, titanite, and rutile. The process resulted in significant gain of K, Rb, Ba, and Sr, accompanied by loss of Fe and Na, with metals such as Cu, Zn, Sn, W, and Tl showing significant mobility. Concurrently, the increasing fluid acidity, due to interaction with Ca‐rich fluids, resulted in a diffuse Ca‐metasomatism. During this stage, a wide variety of calc‐silicates formed (diopside, titanite, vesuvianite, garnet, and allanite), throughout the granite body, along granite joints, and at the carbonate−granite contact. In the following stage, Ca‐F‐rich fluids triggered the acidic metasomatism of accessory minerals and the mobilization of high-field-strength elements (HFSE) and REE. This stage is characterized by the exchange of major elements (Ti, Ca, Fe, Al) with HFSE and REE in the forming metasomatic minerals (i.e., titanite, vesuvianite) and the crystallization of HFSE‐REE minerals. Moreover, the observed textural disequilibrium of newly formed minerals (pseudomorphs, patchy zoning, dissolution/reprecipitation textures) suggests the evolution of metasomatizing fluids towards more acidic conditions at lower temperatures. In summary, the selective mobilization of chemical components was related to a shift in fluid composition, pH, and temperature. This study emphasizes the importance of relating field studies and petrographic observations to detailed mineral compositions, leading to the construction of litho‐geochemical models for element mobilization in crustal magmatic‐hydrothermal settings.
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- 2019
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27. Tourmaline as a Tracer of Late-Magmatic to Hydrothermal Fluid Evolution: The World-Class San Rafael Tin (-Copper) Deposit, Peru
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Matthieu Harlaux, Andrea Rielli, Miroslav Kalinaj, Oscar Laurent, Andrew Menzies, Alain Chauvet, Andrea Dini, Kalin Kouzmanov, Stefano Gialli, Lluis Fontboté, Université de Genève (UNIGE), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), The Wellcome Trust Sanger Institute [Cambridge], and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS)
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Tourmaline ,[SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography ,Geochemistry ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Hydrothermal circulation ,[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry ,Geochemistry and Petrology ,Breccia ,[SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology ,ddc:550 ,010503 geology ,isotopes ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Arsenopyrite ,Sn ore deposit ,Cassiterite ,Trace element ,Geology ,mineral chemistry ,Geophysics ,[SDU]Sciences of the Universe [physics] ,13. Climate action ,visual_art ,visual_art.visual_art_medium ,engineering ,Phenocryst ,Economic Geology ,Vein (geology) ,[SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy - Abstract
The world-class San Rafael tin (-copper) deposit (central Andean tin belt, southeast Peru) is an exceptionally large and rich (>1 million metric tons Sn; grades typically >2% Sn) cassiterite-bearing hydrothermal vein system hosted by a late Oligocene (ca. 24 Ma) peraluminous K-feldspar-megacrystic granitic complex and surrounding Ordovician shales affected by deformation and low-grade metamorphism. The mineralization consists of NW-trending, quartz-cassiterite-sulfide veins and fault-controlled breccia bodies (>1.4 km in vertical and horizontal extension). They show volumetrically important tourmaline alteration that principally formed prior to the main ore stage, similar to other granite-related Sn deposits worldwide. We present here a detailed textural and geochemical study of tourmaline, aiming to trace fluid evolution of the San Rafael magmatic-hydrothermal system that led to the deposition of tin mineralization. Based on previous works and new petrographic observations, three main generations of tourmaline of both magmatic and hydrothermal origin were distinguished and were analyzed in situ for their major, minor, and trace element composition by electron microprobe analyzer and laser ablation-inductively coupled plasma-mass spectrometry, as well as for their bulk Sr, Nd, and Pb isotope compositions by multicollector-inductively coupled plasma-mass spectrometry. A first late-magmatic tourmaline generation (Tur 1) occurs in peraluminous granitic rocks as nodules and disseminations, which do not show evidence of alteration. This early Tur 1 is texturally and compositionally homogeneous; it has a dravitic composition, with Fe/(Fe + Mg) = 0.36 to 0.52, close to the schorl-dravite limit, and relatively high contents (10s to 100s ppm) of Li, K, Mn, light rare earth elements, and Zn. The second generation (Tur 2)—the most important volumetrically—is pre-ore, high-temperature (>500°C), hydrothermal tourmaline occurring as phenocryst replacement (Tur 2a) and open-space fillings in veins and breccias (Tur 2b) and microbreccias (Tur 2c) emplaced in the host granites and shales. Pre-ore Tur 2 typically shows oscillatory zoning, possibly reflecting rapid changes in the hydrothermal system, and has a large compositional range that spans the schorl to dravite fields, with Fe/(Fe + Mg) = 0.02 to 0.83. Trace element contents of Tur 2 are similar to those of Tur 1. Compositional variations within Tur 2 may be explained by the different degree of interaction of the magmatic-hydrothermal fluid with the host rocks (granites and shales), in part because of the effect of replacement versus open-space filling. The third generation is syn-ore hydrothermal tourmaline (Tur 3). It forms microscopic veinlets and overgrowths, partly cutting previous tourmaline generations, and is locally intergrown with cassiterite, chlorite, quartz, and minor pyrrhotite and arsenopyrite from the main ore assemblage. Syn-ore Tur 3 has schorl-foititic compositions, with Fe/(Fe + Mg) = 0.48 to 0.94, that partly differ from those of late-magmatic Tur 1 and pre-ore hydrothermal Tur 2. Relative to Tur 1 and Tur 2, syn-ore Tur 3 has higher contents of Sr and heavy rare earth elements (10s to 100s ppm) and unusually high contents of Sn (up to >1,000 ppm). Existence of these three main tourmaline generations, each having specific textural and compositional characteristics, reflects a boron-rich protracted magmatic-hydrothermal system with repeated episodes of hydrofracturing and fluid-assisted reopening, generating veins and breccias. Most trace elements in the San Rafael tourmaline do not correlate with Fe/(Fe + Mg) ratios, suggesting that their incorporation was likely controlled by the melt/fluid composition and local fluid-rock interactions. The initial radiogenic Sr and Nd isotope compositions of the three aforementioned tourmaline generations (0.7160–0.7276 for 87Sr/86Sr(i) and 0.5119–0.5124 for 143Nd/144Nd(i)) mostly overlap those of the San Rafael granites (87Sr/86Sr(i) = 0.7131–0.7202 and 143Nd/144Nd(i) = 0.5121–0.5122) and support a dominantly magmatic origin of the hydrothermal fluids. These compositions also overlap the initial Nd isotope values of Bolivian tin porphyries. The initial Pb isotope compositions of tourmaline show larger variations, with 206Pb/204Pb(i), 207Pb/204Pb(i), and 208Pb/204Pb(i) ratios mostly falling in the range of 18.6 to 19.3, 15.6 to 16.0, and 38.6 to 39.7, respectively. These compositions partly overlap the initial Pb isotope values of the San Rafael granites (206Pb/204Pb(i) = 18.6–18.8, 207Pb/204Pb(i) = 15.6–15.7, and 208Pb/204Pb(i) = 38.9–39.0) and are also similar to those of other Oligocene to Miocene Sn-W ± Cu-Zn-Pb-Ag deposits in southeast Peru. Rare earth element patterns of tourmaline are characterized, from Tur 1 to Tur 3, by decreasing (Eu/Eu*)N ratios (from 20 to 2) that correlate with increasing Sn contents (from 10s to >1,000 ppm). These variations are interpreted to reflect evolution of the hydrothermal system from reducing toward relatively more oxidizing conditions, still in a low-sulfidation environment, as indicated by the pyrrhotite-arsenopyrite assemblage. The changing textural and compositional features of Tur 1 to Tur 3 reflect the evolution of the San Rafael magmatic-hydrothermal system and support the model of fluid mixing between reduced, Sn-rich magmatic fluids and cooler, oxidizing meteoric waters as the main process that caused cassiterite precipitation.
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- 2020
28. Magnesio-lucchesiite, CaMg3Al6(Si6O18)(BO3)3(OH)3O, a new species of the tourmaline supergroup
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Lee A. Groat, R. James Evans, Paolo Orlandi, Andrea Dini, Marco Pasero, Ulf Hålenius, Jan Cempírek, Emily D. Scribner, Ferdinando Bosi, and Cristian Biagioni
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010504 meteorology & atmospheric sciences ,Tourmaline ,O'Grady Batholith ,beryllium and boron: Quintessentially crustal ,Geochemistry ,Lithium ,new mineral species ,Magnesio-lucchesiite ,010502 geochemistry & geophysics ,01 natural sciences ,lamprophyre dike ,San Piero in Campo ,Geophysics ,Geochemistry and Petrology ,Elba Island ,lithium ,Supergroup ,Geology ,0105 earth and related environmental sciences - Abstract
Magnesio-lucchesiite, ideally CaMg3Al6(Si6O18)(BO3)3(OH)3O, is a new mineral species of the tourmaline supergroup. The holotype material was discovered within a lamprophyre dike that cross-cuts tourmaline-rich metapelites within the exocontact of the O’Grady Batholith, Northwest Territories (Canada). Two additional samples were found at San Piero in Campo, Elba Island, Tuscany (Italy) in hydrothermal veins embedded in meta-serpentinites within the contact aureole of the Monte Capanne intrusion. The studied crystals of magnesio-lucchesiite are black in a hand sample with vitreous luster, conchoidal fracture, an estimated hardness of 7–8, and a calculated density of 3.168 (Canada) and 3.175 g/cm3 (Italy). In plane-polarized light, magnesio-lucchesiite is pleochroic (O = dark brown, E = colorless) and uniaxial (–); its refractive index values are nω = 1.668(3) and nε = 1.644(3) (Canada), and nω = 1.665(5) and nε = 1.645(5) (Italy). Magnesio-lucchesiite is trigonal, space group R3m, Z = 3, with a = 15.9910(3) Å, c = 7.2224(2) Å, V = 1599.42(7) Å3 (Canada) and with a = 15.9270(10) Å, c = 7.1270(5) Å, V = 1565.7(2) Å3 (Italy, sample 1). The crystal structure of magnesio-lucchesiite was refined to R1 = 3.06% using 2953 reflections with Fo > 4σ(Fo) (Canadian sample; 1.96% / 1225 for the Italian sample) The Canadian (holotype) sample has the ordered empirical formula X(Ca0.60Na0.39K0.01)Σ1.00Y(Mg2.02Fe0.622+Fe0.093+Ti0.25V0.01Cr0.01)Σ3.00Z(Al5.31Fe0.693+)Σ6.00[T(Si5.98Al0.02)Σ6.00O18](BO3)3V[(OH)2.59O0.41]Σ3.00W(O0.78F0.22)Σ1.00. The Italian (co-type) material shows a wider chemical variability, with two different samples from the same locality having ordered chemical formulas: X(Ca0.88Na0.12)Σ1.00Y(Mg1.45Fe0.402+Al0.79Fe0.363+)Σ3.00ZAl6[T(Si5.05Al0.95)Σ6.00O18](BO3)3V[(OH)2.90O0.10]Σ3.00W(O0.98F0.02)Σ1.00 (sample 1) and X(Ca0.71Na0.21☐0.08)Σ1.00Y(Mg2.49Fe0.412+Ti0.10)Σ3.00Z(Al5.44Fe0.463+Mg0.09V0.01)Σ6.00[T(Si5.87Al0.13)Σ6.00O18](BO3)3V(OH)3W[O0.61(OH)0.39]Σ1.00 (sample 2). Magnesio-lucchesiite is an oxy-species belonging to the calcic group of the tourmaline supergroup. It is related to lucchesiite by the homovalent substitution YFe ↔ YMg, and to feruvite by the homovalent and heterovalent substitutions YFe ↔ YMg and ZAl3+ + WO2– ↔ ZMg2+ + W(OH)1–. The new mineral was approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA 2019-025). Occurrences of magnesio-lucchesiite show that its presence is not restricted to replacement of mafic minerals only; it may also form in metacarbonate rocks by fluctuations of F and Al during crystallization of common uvitic tourmaline. High miscibility with other tourmaline end-members indicates the large petrogenetic potential of magnesio-lucchesiite in Mg, Al-rich calc-silicate rocks, as well as contact-metamorphic and metasomatic rocks.
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- 2021
29. Muon Radiography of Ancient Mines: The San Silvestro Archaeo-Mining Park (Campiglia Marittima, Tuscany)
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Guglielmo Baccani, Lorenzo Bonechi, Massimo Bongi, Debora Brocchini, Nicola Casagli, Roberto Ciaranfi, Luigi Cimmino, Vitaliano Ciulli, Raffaello D’Alessandro, Chiara Del Ventisette, Andrea Dini, Giovanni Gigli, Sandro Gonzi, Silvia Guideri, Luca Lombardi, Barbara Melon, Nicola Mori, Massimiliano Nocentini, Pasquale Noli, Giulio Saracino, and Lorenzo Viliani
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muon radiography ,cosmic rays ,tracking detectors ,imaging ,geophysical prospection ,mining ,Elementary particle physics ,QC793-793.5 - Abstract
Muon absorption radiography is an imaging technique based on the measurement of the absorption of cosmic ray muons. This technique has recently been used successfully to investigate the presence of unknown cavities in the Bourbon Gallery in Naples and in the Chephren Pyramid at Cairo. The MIMA detector (Muon Imaging for Mining and Archaeology) is a prototype muon tracker for muon radiography for application in the fields of archaelogy and mining. It is made of three pairs of X-Y planes each consisting of 21 scintillator bars with a silicon photomultiplier readout. The detector is compact, robust, easily transportable, and has a low power consumption: all of which makes the detector ideal for measurements in confined and isolated environments. With this detector, a measurement from inside the Temperino mine in the San Silvestro archaeo-mining park in Tuscany was performed. The park includes about 25 km of mining tunnels arranged on several levels that have been exploited from the Etruscan time. The measured muon absorption was compared to the simulated one, obtained from the information provided by 3D laser scanner measurements and cartographic maps of the mountain above the mine, in order to obtain information about the average density of the rock. This allowed one to confirm the presence of a partially accessible exploitation opening and provided some hints regarding the presence of a high-density body within the rock.
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- 2019
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30. Absorption-based muography for ore bodies prospecting: a case study from Temperino Mine (Italy)
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Tommaso Beni, Guglielmo Baccani, Diletta Borselli, Lorenzo Bonechi, Massimo Bongi, Debora Brocchini, Nicola Casagli, Roberto Ciaranfi, Luigi Cimmino, Vitaliano Ciulli, Raffaello D'Alessandro, Chiara Del Ventisette, Andrea Dini, Giovanni Gigli, Sandro Gonzi, Silvia Guideri, Luca Lombardi, Nicola Mori, Massimiliano Nocentini, Pasquale Noli, Giulio Saracino, and Lorenzo Viliani
- Abstract
In the last twenty years several applications of muography (or muon radiography) technique have been carried out for geological purposes. Among them, particular attention was given to underground ore bodies prospections. For thousands of years humans have been searching new methods to understand where to find underground ore bodies and how to localize it in the three-dimensional space. Often, economically useful minerals are bounded to other minerals, forming rocks of high density values that are hosted, usually, in rocks with lower density values. In literature gravimetry and magnetometry represent the most employed geophysical methods for imaging and detection of mineral-rich ore bodies. To verify the feasibility of muography as a non-invasive geophysical prospecting technique, our research group, composed by subnuclear physicists and geologists, carried out some underground measurement campaigns at the Temperino Mine (Campiglia Marittima, Italy). Here it is located a pliocenic metasomatic ore deposit, a Cu-Pb-Zn-Fe skarn complex composed by johannsenite, quartz, hedenbergite, ilvaite and accessory primary sulphides (chalcopyrite, galena, sphalerite, pyrite). These metalliferous bodies of skarn have tabular geometries with sub-vertical orientations. Currently, the first level of Temperino Mine has been equipped as a touristic path and belong to the Archeological Mining Park of San Silvestro. Along this gallery, carved both into the metamorphic and non-metamorphic rocks, it’s been installed the MIMA muon tracker (Muon Imaging for Mining and Archaeology), a small and rugged prototype (0.5 x 0.5. x 0.5 m3) developed by the physicists of the National Institute of Nuclear Physics (INFN), unit of Florence, and the Department of Physics and Astronomy of Florence. MIMA detector is able to measure the underground muon flux inside the mine gallery. Matching the simulated muon transmission rate with the experimentally measured one it’s possible to obtain a two dimensional average density angular map of the observed target. Also, using algorithms based on triangulation and back-projection techniques is possible to obtain a reconstruction of the 3D volume of high-density areas (and also low-density areas) inside the studied volume. The latter is the volume that falls within the detector’s acceptance. The aim of this research is to obtain a georeferenced 3D model of the Cu-Pb-Zn ore bodies hosted in the rocks between the top of the mine gallery and the surface of the Temperino Mine area. We want to confirm that muography technique could become a suitable and reliable tool for the mining prospections field.
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- 2022
31. Identification and three-dimensional localization of cavities at the Temperino mine (Tuscany-Italy) with the muon imaging technique
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Diletta Borselli, Guglielmo Baccani, Tommaso Beni, Lorenzo Bonechi, Massimo Bongi, Debora Brocchini, Nicola Casagli, Roberto Ciaranfi, Luigi Cimmino, Vitaliano Ciulli, Raffaello D'Alessandro, Chiara Del Ventisette, Andrea Dini, Giovanni Gigli, Sandro Gonzi, Silivia Guideri, Luca Lombardi, Massimiliano Nocentini, Pasquale Noli, Nicola Mori, Giulio Saracino, and Lorenzo Viliani
- Abstract
Muon radiography is a non-invasive imaging technique that allows, through cosmic muon absorption measurements, to obtain two-dimensional and three-dimensional images of the internal structure and average density of very large material volumes. Its applications currently range from many fields: geological, archaeological, industrial, civil and nuclear safety. The technique of muon radiography being non-invasive represents a valid alternative to the common survey techniques in these fields of applications. In this presentation I will show some results obtained with this technique in the geological field for the three-dimensional imaging of cavities and tunnels within the Temperino mine located in the San Silvestro Archaeological Mining Park near Campiglia Marittima in the province of Livorno in Tuscany (Italy). The Temperino mine has ancient etruscan origins and still has areas which are not mapped in the available documentation. The mining activities of the area have always been focused on the search for a hard and dense rock called skarn in which there are metallic sulphides of Cu, Ag, Pb, Zn, Fe. Currently only one of the most superficial levels of the mine is accessible to the public through a tourist route. The muographic measurements on this site therefore have a dual objective, on the one hand to test the imaging technique on known cavities, on the other hand to discover new cavities whose knowledge could be useful, for example, for important assessments concerning historical and safety aspect of the site. All measurements were carried out with the muon detector MIMA (Muon Imaging for Mining and Archaeology) designed and built at the National Institute of Nuclear Physics (INFN) in Florence. MIMA is a cubic tracker of approximate dimensions (50x50x50) cm3and is equipped with a special protective aluminum mechanism that allows its altazimuth orientation. Various measurements were made within the tourist gallery located about 50 m below ground level for the observation of areas above. By comparing muon transmission measurements with simulations, it was possible to generate two-dimensional angular maps of average density of material observed in every direction within the detector's acceptance. The presence of some low-density anomalies associated with the presence of cavities was thus identified. Through algorithms based on the triangulation technique and on a track backprojection technique, the cavities were located in three-dimensions. For the known cavities it was also possible to compare the reconstructed development with their real profile that was acquired with the laser scanner technique, finding a good compatibility (average deviation below 1 m for a 7 m high cavity located 20 m above the detector’s installation location). These measurements therefore validate the muon radiography technique in the geological field for the search for cavities inside mines. The technique can be applied to identify not only low-density anomalies or voids, but also high-density areas: the application of the muon imaging technique for the identification of dense ore bodies is being studied at Temperino mine.
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- 2022
32. Anatectic Lithium-Cesium-Tantalum pegmatites formation during low pressure metamorphism of metapelites
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Lorenzo Magnani, Federico Farina, Federico Pezzotta, Andrea Dini, Matthew Mayne, and Omar Bartoli
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- 2022
33. Il litio dalla geotermia: una nuova opportunità
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Andrea, Dini, Fiorenzo, Fumanti, Nunzia, Bernardo, Emanuele, Emani, Marcello, Saralli, Domenico, Savoca, Maria Grazia Verdura, Vico, Giuseppe, and Litio, Wg
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litio ,fluidi geotermici ,Direct Lithium Extraction - Published
- 2022
34. Metasomatism and cyclic skarn growth along lithological contacts: Physical and geochemical evidence from a distal Pb Zn skarn
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Oscar Laurent, Aaron L. Hantsche, Thomas Edward Sheldrake, Andrea Dini, Georgi Milenkov, Rossitsa D. Vassileva, Simone Vezzoni, Kalin Kouzmanov, Marcel Guillong, Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Institute of Geochemistry and Petrology [ETH Zürich], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
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010504 meteorology & atmospheric sciences ,Clinozoisite ,Geochemistry ,[SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,Geology ,Skarn ,Epidote ,Pyroxene ,engineering.material ,distal skarn ,skarn formation ,metasomatism ,mineral geochemistry ,pyroxene ,epidote ,Pb-Zn deposit ,Madan ,010502 geochemistry & geophysics ,Fluid transport ,01 natural sciences ,Geochemistry and Petrology ,[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry ,engineering ,[SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology ,Metasomatism ,Protolith ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Gneiss - Abstract
Distal skarns form by the metasomatic reactions of a host rock induced by far-traveled hydrothermal fluids. Physical and structural characteristics and geochemical patterns of distal Pb Zn skarn bodies were studied at the Petrovitsa deposit in southern Bulgaria. Skarn bodies formed from the interaction of hydrothermal fluids with reactive host lithologies (marble and gneiss). These fluids were transported along sub-vertical feeder structures and lithological contacts. Epidote skarn developed in gneiss protolith, and pyroxene (johannsenite) skarn developed in marble. Detailed geological mapping, complimented by measurements of the internal structure of the skarn body using pyroxene growth versors, quantifies the propagation direction of the skarn body: 1) away from the major local fluid conduit (feeder structure), and 2) away from lithological contacts between aluminosilicate rock and marble. Such growth suggests that fluid flow was generally orthogonal to the skarn front propagation direction in the pyroxene skarn. Textural, mineralogical and geochemical data from skarn samples reveal multiple growth generations of major skarn calc-silicates epidote and pyroxene. The epidote skarn is characterized by limited spatial distribution and fine-grained epidote/clinozoisite growth associated with massive replacement and sulfide mineralization. The pyroxene skarn consists of acicular clinopyroxene crystals which form spheroidal aggregates with discrete growth banding. These bands are the physical representation of the cyclic fluid pulses which resulted in rhythmic skarn growth marked by geochemical banding. In situ geochemical analyses in the epidote skarn reveal early Al-rich epidote overprinted by Fe-rich epidote associated with higher Mn and Sr contents and irregular compositional banding. Clinopyroxene (Jo60–95) shows general increase in Na, Al, Mn, and REE + Y with distance from the feeder structure and lithologic contacts. These elements correlate with the distance traveled by the hydrothermal fluid from the feeder to the site of skarnification, which we define using a proxy based on the Al content of pyroxene crystals. This reflects an increasing degree of fluid “contamination” by interaction with the aluminosilicate host rocks and functions as a proxy for fluid transport distance. The spatial distribution of trace-elements in pyroxene on an outcrop scale is indicative of discrete pulses of hydrothermal fluid resulting in precipitation of skarn calc-silicates along the increasingly tortuous fluid pathway between the feeder structure and the skarn front, resulting in both the macro- and micro-scale chemical and textural variability of the skarn body.
- Published
- 2021
35. Structural Controls of Ore Mineralization in a Polydeformed Basement: Field Examples from the Variscan Baccu Locci Shear Zone (SE Sardinia, Italy)
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Antonio Funedda, Stefano Naitza, Cristina Buttau, Fabrizio Cocco, and Andrea Dini
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sulphide lenses ,hinge trap ,dilational jogs ,orogenic gold ,mafic dikes ,mineralization chronology ,arsenopyrite ,late Variscan strike-slip faults ,Mineralogy ,QE351-399.2 - Abstract
The Baccu Locci mine area is located in a sector of the Variscan Nappe zone of Sardinia (the Baccu Locci shear zone) that hosts several type of ore deposits mined until the first half of the last century. The orebodies consist of lenses of Zn–Cu sulphides, once interpreted as stratabound, and Qtz–As–Pb sulphide ± gold veins; the implication of structural controls in their origin were previously misinterpreted or not considered. Detailed field mapping, structural analyses, and ore mineralogy allowed for unraveling how different ore parageneses are superimposed each other and to recognize different relationships with the Variscan structures. The sulphide lenses are parallel to the mylonitic foliation, hosted in the hinges of minor order upright antiforms that acted as traps for hydrothermal fluids. The Qtz–As–Pb sulphide veins crosscut the sulphide lenses and are hosted in large dilatational jogs developed in the hanging wall of dextral-reverse faults, whose geometry is influenced by the attitude of reverse limbs of late Variscan folds. The ores in the Baccu Locci shear zone are best interpreted as Variscan orogenic gold-type; veins display mutual crosscutting relationships with mafic dikes dated in the same district at 302 ± 0.2 Ma, a reliable age for the mineralizing events in the area.
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- 2018
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36. Fluid mixing as primary trigger for cassiterite deposition: Evidence from in situ ?18O-?11B analysis of tourmaline from the world-class San Rafael tin (-copper) deposit, Peru
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Stefano Gialli, Anne-Sophie Bouvier, Andrea Rielli, Alain Chauvet, Kalin Kouzmanov, Andrea Dini, Lluis Fontboté, Lukas P. Baumgartner, Matthieu Harlaux, Miroslav Kalinaj, Katharina Marger, Université de Genève (UNIGE), Institute of Earth Sciences [Lausanne], University of Lausanne (UNIL), CNR Istituto di Geoscienze e Georisorse [Pisa] (IGG-CNR), Consiglio Nazionale delle Ricerche (CNR), Géosciences Montpellier, and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)
- Subjects
tourmaline ,010504 meteorology & atmospheric sciences ,Tourmaline ,δ18O ,tin deposit ,Geochemistry ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Hydrothermal circulation ,Isotopes of oxygen ,hydrothermal fluids ,boron isotopes ,fluid mixing ,Geochemistry and Petrology ,[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry ,Earth and Planetary Sciences (miscellaneous) ,ddc:550 ,Rayleigh fractionation ,0105 earth and related environmental sciences ,Geochemical modeling ,oxygen isotopes ,Cassiterite ,Geophysics ,13. Climate action ,Space and Planetary Science ,engineering ,Deposition (chemistry) ,Geology - Abstract
We present a high-resolution in situ study of oxygen and boron isotopes measured in tourmaline from the world-class San Rafael Sn (–Cu) deposit (Central Andean tin belt, Peru) aiming to trace major fluid processes at the magmatic-hydrothermal transition leading to the precipitation of cassiterite. Our results show that late-magmatic and pre-ore hydrothermal tourmaline has similar values of δ 18 O (from 10.6‰ to 14.1‰) and δ 11 B (from −11.5‰ to −6.9‰). The observed δ 18 O and δ 11 B variations are dominantly driven by Rayleigh fractionation, reflecting tourmaline crystallization in a continuously evolving magmatic-hydrothermal system. In contrast, syn-ore hydrothermal tourmaline intergrown with cassiterite has lower δ 18 O values (from 4.9‰ to 10.2‰) and in part higher δ 11 B values (from −9.9‰ to −5.4‰) than late-magmatic and pre-ore hydrothermal tourmaline, indicating important contribution of meteoric groundwater to the hydrothermal system during ore deposition. Quantitative geochemical modeling demonstrates that the δ 18 O- δ 11 B composition of syn-ore tourmaline records variable degrees of mixing of a hot Sn-rich magmatic brine with meteoric waters that partially exchanged with the host rocks. These results provide thus direct in situ isotopic evidence of fluid mixing as a major mechanism triggering cassiterite deposition. Further, this work shows that combined in situ δ 18 O and δ 11 B analyses of tourmaline is a powerful approach for understanding fluid processes in dynamic magmatic-hydrothermal environments.
- Published
- 2021
- Full Text
- View/download PDF
37. Tectonically driven carbonation of serpentinite by mantle CO2: Genesis of the Castiglioncello magnesite deposit in the Ligurian ophiolite of central Tuscany (Italy)
- Author
-
Andrea Rielli, Chiara Boschi, and Andrea Dini
- Subjects
Geochemistry and Petrology ,Economic Geology ,Geology - Published
- 2022
38. Origin of Monte Rosa whiteschist from in-situ tourmaline and quartz oxygen isotope analysis by SIMS using new tourmaline reference materials
- Author
-
Andrea Dini, Lukas P. Baumgartner, Benita Putlitz, Katharina Marger, Anne-Sophie Bouvier, Cindy Luisier, and Barbara L. Dutrow
- Subjects
In situ ,Monte Rosa ,Materials science ,010504 meteorology & atmospheric sciences ,Tourmaline ,oxygen isotopes ,Analytical chemistry ,010502 geochemistry & geophysics ,quartz ,01 natural sciences ,Isotopes of oxygen ,whiteschist-tourmaline ,Tourmaline reference materials ,Geophysics ,Geochemistry and Petrology ,Whiteschist ,SIMS ,Quartz ,0105 earth and related environmental sciences - Abstract
A series of tourmaline reference materials are developed for in situ oxygen isotope analysis by secondary ion mass spectrometry (SIMS), which allow study of the tourmaline compositions found in most igneous and metamorphic rocks. The new reference material was applied to measure oxygen isotope composition of tourmaline from metagranite, meta-leucogranite, and whiteschist from the Monte Rosa nappe (Western Alps). The protolith and genesis of whiteschist are highly debated in the literature. Whiteschists occur as 10 to 50 m tube-like bodies within the Permian Monte Rosa granite. They consist of chloritoid, talc, phengite, and quartz, with local kyanite, garnet, tourmaline, and carbonates. Whiteschist tourmaline is characterized by an igneous core and a dravitic overgrowth (XMg > 0.9). The core reveals similar chemical composition and zonation as meta-leucogranitic tourmaline (XMg = 0.25, δ18O = 11.3–11.5‰), proving their common origin. Dravitic overgrowths in whiteschists have lower oxygen isotope compositions (8.9–9.5‰). Tourmaline in metagranite is an intermediate schorl-dravite with XMg of 0.50. Oxygen isotope data reveal homogeneous composition for metagranite and meta-leucogranite tourmalines of 10.4–11.3‰ and 11.0–11.9‰, respectively. Quartz inclusions in both meta-igneous rocks show the same oxygen isotopic composition as the quartz in the matrix (13.6–13.9‰). In whiteschist the oxygen isotope composition of quartz included in tourmaline cores lost their igneous signature, having the same values as quartz in the matrix (11.4–11.7‰). A network of small fractures filled with dravitic tourmaline can be observed in the igneous core and suggested to serve as a connection between included quartz and matrix, and lead to recrystallization of the inclusion. In contrast, the igneous core of the whiteschist tourmaline fully retained its magmatic oxygen isotope signature, indicating oxygen diffusion is extremely slow in tourmaline. Tourmaline included in high-pressure chloritoid shows the characteristic dravitic overgrowth, demonstrating that chloritoid grew after the metasomatism responsible for the whiteschist formation, but continued to grow during the Alpine metamorphism. Our data on tourmaline and quartz show that tourmaline-bearing white-schists originated from the related meta-leucogranites, which were locally altered by late magmatic hydrothermal fluids prior to Alpine high-pressure metamorphism.
- Published
- 2019
39. Fluid transfer and vein thickness distribution in high and low temperature hydrothermal systems at shallow crustal level in southern Tuscany (Italy)
- Author
-
Francesco Mazzarini, Giovanni Ruggieri, Ilaria Isola, Chiara Boschi, Andrea Dini, Giovanni Musumeci, and Sergio Rocchi
- Subjects
Hydrothermal systems ,Vein thickness distribution ,Transmissivity ,Tuscany ,Meteorology. Climatology ,QC851-999 ,Geophysics. Cosmic physics ,QC801-809 - Abstract
Geometric analysis of vein systems hosted in upper crustal rocks and developed in high and low temperature hydrothermal systems is presented. The high temperature hydrothermal system consists of tourmaline-rich veins hosted within the contact aureole of the upper Miocene Porto Azzurro pluton in the eastern Elba Island. The low temperature hydrothermal system consists of calcite-rich veins hosted within the Oligocene sandstones of the Tuscan Nappe, exposed along the coast in southern Tuscany. Vein thickness distribution is here used as proxy for inferring some hydraulic properties (transmissivity) of the fluid circulation at the time of veins’ formation. We derive estimations of average thickness of veins by using the observed distributions. In the case of power law thickness distributions, the lower the scaling exponent of the distribution the higher the overall transmissivity. Indeed, power law distributions characterised by high scaling exponents have transmissivity three order of magnitude lower than negative exponential thickness distribution. Simple observations of vein thickness may thus provides some clues on the transmissivity in hydrothermal systems.
- Published
- 2014
- Full Text
- View/download PDF
40. A global hydrothermal reactor triggered prebiotic synthesis on Earth
- Author
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Chiara Boschi, Andrea Dini, Gretchen Früh-Green, and Luca Caricchi
- Published
- 2021
41. Timescales of plutonic-subvolcanic-volcanic connection in a Mio-Pliocene long-lived igneous system (Tuscany): zircon CA-ID-TIMS dating
- Author
-
Maria Ovtcharova, Gabriele Paoli, Andrea Dini, and Sergio Rocchi
- Subjects
geography ,Igneous rock ,geography.geographical_feature_category ,Volcano ,Geochemistry ,Geology ,Connection (mathematics) ,Zircon - Abstract
The genetic link between plutonic and volcanic realms is a key for understanding timescales of igneous plumbing systems, and precise geochronological records are pivotal in estimating the duration of processes at different levels in such plumbing systems. The Campiglia igneous complex, Tuscany, offers exposures of the full range of emplacement levels (plutonic, subvolcanic, volcanic) of mantle- and crust-derived magmas. Magma emplacement occurred astride the Miocene-Pliocene boundary. New high-precision U-Pb CA-ID-TIMS, zircon geochronological data, coupled with LA-HR-ICP-MS zircon dates for the whole Campiglia system define a short crystallization time span for zircon from the peraluminous granite pluton (~100 ka), intermediate for the shallow-level mafic porphyry (~450 ka), and longer for the rhyolite (~700 ka), at odd with what commonly expected. The oldest ages for the three units are the same, leading to hypothesize the occurrence of a bimodal deep reservoir remaining in melt-present conditions for some 700 ka. In this framework, early-crystallized zircons were cannibalized by younger melt batches that were sequentially extracted from the reservoir.
- Published
- 2021
42. The potential for geothermal lithium in Italy
- Author
-
Andrea Dini, Pierfranco Lattanzi, Eugenio Trumpy, and Giovanni Ruggieri
- Subjects
chemistry ,Geochemistry ,Environmental science ,chemistry.chemical_element ,Lithium ,Geothermal gradient - Abstract
Italy has never been a lithium (Li) producer, and the potential for “hard rock” deposits is moderate at best. On the other hand, the increasing demand for Li-based rechargeable batteries fostered new interest in this metal, and prompted the quest for alternative resources. The extraction of Li from geothermal brines (“geothermal lithium”) is currently considered in several countries, including, in Europe, France, Germany, and UK (EGEC, 2020).Italy has vast geothermal resources, and there is a potential for “geothermal lithium” as well. A preliminary survey of literature data pointed out several occurrences of fluids with Li contents up to hundreds of mg/L. Among high-enthalpy fluids, we point out those of Cesano, Mofete, and Latera. At Cesano, geothermal fluids contain about 350 mg/L lithium (Calamai et al., 1976). Early studies conducted in the past century (Pauwels et al., 1990) suggested the feasibility of lithium recovery from these fluids. Even higher contents (480 mg/L) occur in the deep reservoir at Mofete (Guglielminetti, 1986), whereas fluids in the shallow and intermediate reservoir in the same field contain 28 to 56 mg/L. Geothermal fluids at Latera have somewhat lower contents (max 13.5 mg/L; Gianelli and Scandiffio, 1989). Several low-enthalpy thermal waters in Emilia-Romagna, Sardinia, Sicily and Tuscany also show significant (> 1 mg/L) Li contents (max 96 mg/L at Salsomaggiore; Boschetti et al., 2011). There are no published Li data for high-enthalpy fluids at Larderello; however, evidence of Li-rich fluids was found in fluid inclusions in hydrothermal minerals (Cathelineau et al., 1994). Moreover, the shallow (ca. 3.5 km) granitoid body underlying the field contains a Li-rich (about 1,000 ppm) biotite (A. Dini, unpublished data); it has been estimated that such rock may contain as much as 500 g Li per cubic meter. ReferencesBoschetti T., et al. - Aquat Geochem (2011) 17:71–108Calamai A., et al. - Proc. U.N. Symp. Development Use Geotherm. Energy, S. Francisco, USA (1976), 305-313Cathelineau M., et al. – Geochim. Cosmochim. Acta (1994) 58: 1083-1099EGEC (European Geothermal Council). https://www.egec.org/time-to-invest-in-clean-geothermal-lithium-made-in-europe/. Accessed December 2, 2020.Gianelli G., Scandiffio G. - Geothermics (1989) 18: 447-463Guglielminetti M. - Geothermics (1986) 15: 781-790Pauwels H., et al. - Proc. 12th New Zealand Geothermal Workshop (1990), 117-123
- Published
- 2021
43. Magma and hydrothermal fluids exploiting similar crustal traps at Gavorrano (Tuscany)
- Author
-
Luca Tinagli, Sergio Rocchi, Simone Vezzoni, and Andrea Dini
- Subjects
Magma ,Petrology ,Geology ,Hydrothermal circulation - Abstract
The 3D reconstruction of magmatic, metasomatic and/or ore bodies plays a major role in understanding the emplacement mechanisms for magmas and hydrothermal fluids in the upper crust.The Gavorrano Intrusive-Hydrothermal Complex (GIHC, Tuscany, Italy) is an excellent case study in which intrusive and hydrothermal rocks, as well as sulphides ore bodies are spatially associated.The evolution of the GIHC starts in the early Pliocene with the sequential emplacement, at the contact between the Paleozoic basement (metapelites) and the overlying Mesozoic limestone-dolostone formations, of a cordierite-biotite monzogranite and a tourmaline microgranite. The monzogranite is highly porphyritic with megacrysts of K-feldspar and phenocrysts of quartz, plagioclase, biotite, and cordierite. The microgranite is characterised by a huge number of euhedral microliths (10-500 µm) of black tourmaline set in a quartz-feldspars groundmass. The small size of the Gavorrano intrusion (ca. 3 x 1 km) and its shallow emplacement level (ca. 5 km) resulted in a thin contact aureole (< 100 m thick) made of phlogopite-olivine marble and biotite-andalusite pelitic hornfels. Isoclinal folds in marble are indicative of dynamic crystallization during contact metamorphism and point out an outward sense of movement of the aureole rocks with respect to the granite intrusion. At the contact with the intrusion, marbles were overprinted by a discontinuous (0.1-10 m thick) layer of vesuvianite-garnet exoskarn. Exoskarn, contact aureole and undisturbed host rocks, were subsequently affected by hydraulic brecciation. The closing stage of the evolution of the complex is characterized by mineralizing fluid circulation, producing widespread chloritization-silicification and decametric pyrite bodies (with adularia, fluorite, and base metal sulfides). Surface and underground mapping integrated by mining reports and drill logs allow us gave way to the reconstruction of the attitude and shape of magmatic and hydrothermal bodies. The NW-SE elongated intrusion is characterised by a pronounced asymmetry: the eastern part is made of sub-horizontal multiple bodies, locally with both roof and bottom contacts exposed; the western part has an overall sub-vertical, west-dipping attitude. Such an asymmetry is shown by each of the two intrusive units and highlighted by second order features: the monzogranite unit reaches its maximum thickness (0.8 km) in the central-western subvertical zone while in the subhorizontal eastern branches is few hundred meters thick, and the subhorizontal microgranite bodies display steep west-dipping offshoots. The GIHC asymmetry is also exhibited by the hydrothermal system: the pyrite orebodies mantle the top and the western flank of the intrusion, with the two main masses displaying, in vertical section, a sigmoidal shape with a steep west-dipping thick portion connecting upper and lower tails gently dipping to the west.The collected data indicate the west side of the GIHC as the focus zone for both magmas and hydrothermal fluids. The overall geometries of the intrusive units and pyrite bodies suggest a sense of movement top-down-to-the-west. This close spatial and shape relationship between intrusive rocks and hydrothermal bodies suggests a common extensional tectono-magmatic regime capable to produce asymmetric crustal traps (dilational structures) for magmas and fluids.
- Published
- 2021
44. 'Geothermal lithium': a new resource for Italy?
- Author
-
Pierfranco Lattanzi, Andrea Dini, Eugenio Trumpy, and Giovanni Ruggieri
- Subjects
Resource (biology) ,chemistry ,Environmental protection ,General Engineering ,chemistry.chemical_element ,Environmental science ,Lithium ,Geothermal gradient - Published
- 2021
45. Sequestration of mantle CO2 into the Ligurian Ophiolites of Central Tuscany
- Author
-
Chiara Boschi, Andrea Rielli, and Andrea Dini
- Subjects
Geochemistry ,Ophiolite ,Geology ,Mantle (geology) - Published
- 2021
46. Peraluminous magmas and the LCT pegmatitic Li paradox
- Author
-
Luca Caricchi, Kalin Kouzmanov, Andrea Dini, Federico Pezzotta, and Federico Farina
- Subjects
Pegmatite - Published
- 2021
47. Lead-Antimony Sulfosalts from Tuscany (Italy). XX. Members of the Jordanite–Geocronite Series from the Pollone Mine, Valdicastello Carducci: Occurrence and Crystal Structures
- Author
-
Cristian Biagioni, Andrea Dini, Paolo Orlandi, Yves Moëlo, Marco Pasero, and Federica Zaccarini
- Subjects
jordanite ,geocronite ,lead ,antimony ,arsenic ,Pollone mine ,Apuan Alps ,Italy ,Mineralogy ,QE351-399.2 - Abstract
A crystal-chemical study of historical specimens as well as new ones belonging to the jordanite–geocronite series from the Pollone baryte + pyrite ± (Pb-Zn-Ag) ore deposit (Valdicastello Carducci, Apuan Alps, Tuscany, Italy) has been performed. These crystals were collected in quartz extension veins embedded in three different occurrences: (i) baryte + pyrite orebodies; (ii) schist layers interbedded between baryte + pyrite orebodies; and (iii) schists at the contact with pyrite-poor baryte orebodies. Electron-microprobe data indicated the occurrence of three distinct groups of compositions within the sample suite. These correspond to As-bearing geocronite, Sb-rich jordanite, and Sb-bearing jordanite, with mean compositions Pb14Sb3.8As2.2S23, Pb14Sb2.9As3.1S23, and Pb14Sb2.6As3.4S23, respectively. Crystals representative of these different compositions have been investigated through single-crystal X-Ray diffraction studies and their crystal structures have been solved to R1 = 0.078, 0.069, and 0.033, respectively. The unit-cell volume decreases passing through As-bearing geocronite (V = 2149.5(3) Å3) to Sb-bearing jordanite (V = 2132.3(3) Å3). The As-to-Sb substitution takes place preferentially at the Sb4 site; through the increasing of the Sb content, Sb can substitute As also at the As6 site. According to the structural study of the ore deposit, formation of jordanite–geocronite is subordinated to a late Alpine deformative D2 stage, which permitted in situ remobilization of preexisting sulfide ore in small quartz extension veins. Such a local recrystallization would explain the variability of the As/(As + Sb) ratio of the members of the jordanite series, reflecting the heterogeneity of the orebody.
- Published
- 2016
- Full Text
- View/download PDF
48. Origin and metamorphic reworking of the Buca della Vena Tl-rich orebody (Alpi Apuane, Italy)
- Author
-
Cristian Biagioni, Andrea Dini, Giancarlo Molli, Simone Vezzoni, and Diego Pieruccioni
- Subjects
Metamorphic rock ,Geochemistry ,Geology - Abstract
The origin and evolution of an orebody hosted in metamorphic terrane is a prime topic in economic geology because they have implications on exploration as well as on related potential geo-environmental health hazards. The Alpi Apuane orebodies has long been known; however, their ore genesis and the relationships with the Apenninic age deformation and metamorphism is still a matter of debate. Indeed, they are still an interesting field of research, as proved by the recent discovery of a remarkable Tl anomaly associated to the baryte ± pyrite ± Fe-oxides ores of southern Alpi Apuane, northern Tuscany, Italy [1]. The present work reports a new detailed field and underground geological-structural investigation, performed from cartographic- to microscopic-scale, integrated by available drill-logs data, of one of these Tl-rich orebodies - the Buca della Vena ore.The present study gives new insights on some aspect of the ore-forming events and discusses previous interpretations. According to our investigations, the ore settings were acquired during successive geological events related to an early hydrothermal-magmatic phase, likely of Permian age, and to the more recent Apenninic deformations. We suggest that the proto-ore was produced by hydrothermal activity related to the post-Variscan magmatic cycle (documented by the Permian age “Fornovolasco metarhyolite” Fm [2]), causing ore-formation, tourmalinization and hydrothermal alteration halo in the Cambrian-Lower Ordovician phyllites host-rocks. In our model, the ores were then partially exhumed suffering supergene alteration with development of minor Fe-oxides sedimentary mineralizations during the upper Norian-Hettangian. Finally, the previous hydrothermal and sedimentary ores, along with the host-rocks, were involved in the Apenninic orogenesis, and were recrystallized, and partially remobilized acquiring the current mineralogical, textural, and structural settings.References:[1] Biagioni, C., D’Orazio, M., Vezzoni, S., Dini, A., Orlandi, P., 2013. Mobilization of Tl-Hg-As-Sb-(Ag,Cu)-Pb sulfosalt melts during low-grade metamorphism in the Alpi Apuane (Tuscany, Italy). Geology, 41, 747-750.[2] Vezzoni, S., Biagioni, C., D’Orazio, M., Pieruccioni, D., Galanti, Y., Petrelli, M., Molli, G., 2018. Evidence of Permian magmatism in the Alpi Apuane metamorphic complex (Northern Apennines, Italy): New hints for the geological evolution of the basement of the Adria plate. Lithos, 318-319, 104-123.
- Published
- 2020
49. Permian hydrothermal alteration preserved in polymetamorphic basement and constraint for ore-genesis (Alpi apuane, italy)
- Author
-
Diego Pieruccioni, Cristian Biagioni, Andrea Dini, Simone Vezzoni, and Yuri Galanti
- Subjects
Recrystallization (geology) ,Basement ,010504 meteorology & atmospheric sciences ,Metamorphic rock ,lcsh:QE1-996.5 ,Geochemistry ,Alpi Apuane ,Metamorphism ,Permian magmatism ,basement ,hydrothermal alteration ,ore genesis ,010502 geochemistry & geophysics ,01 natural sciences ,Hydrothermal alteration ,Petrography ,lcsh:Geology ,Basement (geology) ,Ore genesis ,General Earth and Planetary Sciences ,Sedimentary rock ,Protolith ,Geology ,0105 earth and related environmental sciences - Abstract
The reconstruction of the polymetamorphic history of basement rocks in orogens is crucial for deciphering past geodynamic evolution. However, the current petrographic features are usually interpreted as the results of the metamorphic recrystallization of primary sedimentary and/or magmatic features. In contrast, metamorphic rocks derived by protoliths affected by premetamorphic hydrothermal alterations are rarely recognized. This work reports textural, mineralogical and geochemical data of metasedimentary and metaigneous rocks from the Paleozoic succession of the Sant&rsquo, Anna tectonic window (Alpi Apuane, Tuscany, Italy). These rocks were recrystallized and reworked during the Alpine tectono-metamorphic event, but the bulk composition and some refractory minerals (e.g., tourmaline) are largely preserved. Our data show that the Paleozoic rocks from the Alpi Apuane were locally altered by hydrothermal fluids prior to Alpine metamorphism, and that the Permian magmatic cycle was likely responsible for this hydrothermal alteration. Finally, the Ishikawa Alteration Index, initially developed for magmatic rocks, was applied to metasedimentary rocks, providing a useful geochemical tool for unravelling the hydrothermal history of Paleozoic rocks, as well as a potential guide to the localization of hidden ore deposits in metamorphic terranes.
- Published
- 2020
50. Spontaneous Serpentine Carbonation Controlled by Underground Dynamic Microclimate at the Montecastelli Copper Mine, Italy
- Author
-
Andrea Rielli, Federica Bedini, Giovanni Zanchetta, Natale Perchiazzi, Andrea Dini, Ilaria Baneschi, Lukas P. Baumgartner, Alexey Ulyanov, and Chiara Boschi
- Subjects
Carbonation ,Geochemistry ,Cu mine ,CO2 mineral sequestration ,hydromagnesite ,kerolite ,serpentinite ,Montecastelli ,underground microclimate ,010501 environmental sciences ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Adit ,Ultramafic rock ,Kerolite ,Paragenesis ,Hydromagnesite ,0105 earth and related environmental sciences ,Geochemical modeling ,Brucite ,Geology ,Geotechnical Engineering and Engineering Geology ,13. Climate action ,engineering - Abstract
Understanding low temperature carbon sequestration through serpentinite&ndash, H2O&ndash, CO2 interaction is becoming increasingly important as it is considered a potential approach for carbon storage required to offset anthropogenic CO2 emissions. In this study, we present new insights into spontaneous CO2 mineral sequestration through the formation of hydromagnesite + kerolite with minor aragonite incrustations on serpentinite walls of the Montecastelli copper mine located in Southern Tuscany, Italy. On the basis of field, petrological, and geochemical observations coupled with geochemical modeling, we show that precipitation of the wall coating paragenesis is driven by a sequential evaporation and condensation process starting from meteoric waters which emerge from fractures into the mine walls and ceiling. A direct precipitation of the coating paragenesis is not compatible with the chemical composition of the mine water. Instead, geochemical modeling shows that its formation can be explained through evaporation of mine water and its progressive condensation onto the mine walls, where a layer of serpentinite powder was accumulated during the excavation of the mine adits. Condensed water produces a homogeneous film on the mine walls where it can interact with the serpentinite powder and become enriched in Mg, Si, and minor Ca, which are necessary for the precipitation of the observed coating paragenesis. The evaporation and condensation processes are driven by changes in the air flow inside the mine, which in turns are driven by seasonal changes of the outside temperature. The presence of &ldquo, kerolite&rdquo, a Mg-silicate, is indicative of the dissolution of Si-rich minerals, such as serpentine, through the water&ndash, powder interaction on the mine walls at low temperature (~17.0 to 18.1 °, C). The spontaneous carbonation of serpentine at low temperature is a peculiar feature of this occurrence, which has only rarely been observed in ultramafic outcrops exposed on the Earth&rsquo, s surface, where instead hydromagnesite predominantly forms through the dissolution of brucite. The high reactivity of serpentine observed, in this study, is most likely due to the presence of fine-grained serpentine fines in the mine walls. Further study of the peculiar conditions of underground environments hosted in Mg-rich lithologies, such as that of the Montecastelli Copper mine, can lead to a better understanding of the physical and chemical conditions necessary to enhance serpentine carbonation at ambient temperature.
- Published
- 2020
- Full Text
- View/download PDF
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