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Dini, Andrea
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Dini, Andrea
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- PublicationRestrictedBrucite-driven CO 2 uptake in serpentinized dunites (Ligurian Ophiolites, Montecastelli, Tuscany)Understanding the mechanism of serpentinite weathering at low temperature – that involves carbonate formation – has become increasingly important because it represents an analog study for a cost-efficient carbon disposal strategy (i.e. carbon mineralization technology or mineral Carbon dioxide Capture and Storage, CCS). At Montecastelli (Tuscany, Italy), on-going spontaneous mineral CO2 sequestration is enhanced by brucite-rich serpentinized dunites. The dunites are embedded in brucite-free serpentinized harzburgites that belong to the ophiolitic Ligurian Units (Northern Apennine thrust-fold belt). Two main serpentinization events produced two distinct mineral assemblages in the reactive dunite bodies. The first assemblage consists of low-T pseudomorphic, mesh-textured serpentine, Fe-rich brucite (up to 20 mol.% Fe(OH)2) and minor magnetite. This was overprinted by a non-pseudomorphic, relatively high-T assemblage consisting of serpentine, Fe-poor brucite (ca. 4 mol% Fe(OH)2) and abundant magnetite. The harzburgite host rock developed a brucite-free paragenesis made of serpentine and magnetite. Present-day interaction of serpentinized dunites with slightly acidic and oxidizing meteoric water, enhances brucite dissolution and leads to precipitation of both Mg-Fe layered double hydroxides (coalingite-pyroaurite, LDHs) and hydrous Mg carbonates (hydromagnesite and nesquehonite). In contrast, the brucite-free serpentinized harzburgites are not affected by the carbonation process. In the serpentinized dunites, different carbonate minerals form depending on brucite composition (Fe-rich vs Fe-poor). Reactions in serpentinized dunites containing Fe-rich brucite produce a carbonate assemblage dominated by LDHs and minor amount of hydromagnesite. Serpentinites with a Fe-poor brucite assemblage contain large amounts of hydromagnesite and minor LDHs. Efficiency of CO2 mineral sequestration is different in the two cases owing to the distinct carbon content of LDHs (ca. 1.5 wt.%) and hydromagnesite (ca. 10 wt.%). Here, for the first time, we link the mineral composition of serpentinized ultramafic rocks to carbonate formation, concluding that Fe-poor brucite maximizes the mineral CCS efficiency.
83 4 - PublicationRestrictedIntroduction: LASI III—Magma pulses and sheets in tabular intrusions(2010-06)
; ; ; ; ;Rocchi, S.; Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy ;Dini, A.; Istituto di Geoscienze e Georisorse, CNR Pisa, Pisa, Italy ;Mazzarini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Westerman, D. S.; Department of Geology, Norwich University, Northfield, Vermont, USA; ; ; The origins of granites and intrusive rocks have been widely discussed for a couple of centuries, and the way volcanoes work and their magma forms have attracted scientists, naturalists, and laymen since the dawn of humankind. However, shallow igneous intrusions, representing the obvious link between the hidden kingdom of Pluto and the fiery realm of Vulcanus, have been partly overlooked, leading to some lack of communication between “plutonic” and “volcanic” researchers. An effort devoted to heal this breach has been contributed to by the establishment of the LASI conferences (named after laccolith and sill, the main types of shallow igneous intrusions).181 24 - PublicationOpen AccessFluid transfer and vein thickness distribution in high and low temperature hydrothermal systems at shallow crustal level in southern Tuscany (Italy)(2014)
; ; ; ; ; ; ; ;Mazzarini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Ruggeri, G.; CNR-IGG, Firenze ;Isola, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Boschi, C.; CNR-IGG, Pisa ;Dini, A.; CNR-IGG, Pisa ;Musumeci, G.; Pisa University ;Rocchi, S.; Pisa University; ; ; ; ; ; Geometric analysis of vein systems hosted in upper crustal rocks and de- veloped 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 Az- zurro pluton in the eastern Elba Island. The low temperature hydrother- mal 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 thick- ness distributions, the lower the scaling exponent of the distribution the higher the overall transmissivity. Indeed, power law distributions char- acterised 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.171 124 - PublicationOpen AccessThe Corchia Cave (Alpi Apuane): a 2 Ma temporal window on the earth climate(2010-09)
; ; ; ; ;Zanchetta, G.; Dipartimento di Scienze della Terra, University of Pisa, Italy ;Isola, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Piccini, L.; Dipartimento di Scienze della Terra, University of Florence, Italy ;Dini, A.; Istituto di Geoscienze e Georisorse, CNR Pisa, Italy; ; ; no abstract186 352 - PublicationOpen AccessThe intrusive complexof the Island of Giglio: geomagnetic characteristics of plutonic facies with low susceptibility contrast(1998-08)
; ; ; ; ; ; ; ;Faggioni, O.; Istituto di Geofisica Marina, Consorzio Universitario della Spezia, Universitá di Pisa, La Spezia, Italy ;Westerman, D.; Department of Geology, Norwich University, Northfield, VT, U.S.A. ;Innocenti, F.; Istituto di Geofisica Marina, Consorzio Universitario della Spezia, Universitá di Pisa, La Spezia, Italy ;Beverini, N.; Istituto di Geofisica Marina, Consorzio Universitario della Spezia, Universitá di Pisa, La Spezia, Italy ;Carmisciano, C.; Istituto di Geofisica Marina, Consorzio Universitario della Spezia, Universitá di Pisa, La Spezia, Italy ;Cavallini, R.; Istituto di Geofisica Marina, Consorzio Universitario della Spezia, Universitá di Pisa, La Spezia, Italy ;Dini, A.; Dipartimento di Scienze della Terra, Universitá di Pisa, Italy; ; ; ; ; ; Two main plutonic facies characterize the intrusive complex of the Island of Giglio, and the trend of their contact at depth has been modelled using a 2D½ analysis based on a detailed geomagnetic survey in order to verify the geological hypothesis of the subsurface geometry of this contact. The magnetic anomaly connected with the discontinuity is quite low, due to the small difference between the magnetic susceptibilities of the two granitic facies. Development of this model of inversion of the magnetic field, which is in good agreement with the geological interpretation, was made possible by: 1) accurate control of the geomagnetic time variations and consequent temporal reduction, 2) a very low level of the artificial magnetic noise, 3) high density of the magnetic survey, 4) detailed knowledge of the mapped geologic contact between facies and of their petrologic characteristics, and 5) direct local measurements of the magnetic susceptibilities of the key lithologies. The model shows the trends of the geological contact, as projected in three E-W sections, that dips eastward in the range between 210 and 540, supporting the geologic hypothesis that the Pietrabona facies represents an external shell of the shallowly emplaced Giglio monzogranite intrusion.228 616 - PublicationRestrictedMultiple hydro-fracturing by boron-rich fluids in the Late Miocene contact aureole of eastern Elba Island (Tuscany, Italy)(2008-08)
; ; ; ; ;Dini, A.; Istituto di Geoscienze e Georisorse, CNR - Pisa, Pisa, Italia ;Mazzarini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Musumeci, G.; Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italia ;Rocchi, S.; Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italia; ; ; In eastern Elba Island (Tuscany, Italy), a shallow crustal level felsic, tourmaline-bearing, dyke-sill swarm of Late Miocene age is associated with abundant tourmaline-quartz hydrothermal veins and metasomatic masses. Development of these veins and masses in the host rocks demonstrates multiple hydro-fracturing by magmatic, boron-rich saline fluid. Tourmalines in felsic dykes are schorl, whereas in veins and metasomatic masses, tourmaline composition ranges from schorl-dravite through dravite to uvite. This compositional shift is evidence for an increasing contribution to the magmatic boron-rich fluids by a Mg-Ca-Ti-rich external component represented by biotite-rich and amphibolite host rocks. This system can be envisaged as an exposed proxy of the high temperature hydrothermal system presently active in the deepest part of the Larderello-Travale geothermal field (Tuscany).173 22