1,720,989 research outputs found
EBSD Maps - Sample IESP3SP78 - Calamita Schists (Elba Island, Italy)
No full textThis dataset contains the EBSD Maps obtained on sample IESP3SP78 (sample registered on SESAR), a full thin section scan and a photo stitching at crossed polars and a file showing the location of the EBSD data.Sample IESP3SP78 is a mylonitic quartzite belonging to the Calamita Schists Fm. (Elba Island, Italy)The interpreted data has been published on Papeschi, S., & Musumeci, G. (2019). Fluid assisted strain localization in quartz at the brittle/ductile transition. Geochemistry, Geophysics, Geosystems 20, 3044-3064.The EBSD maps are provided as core files which are freely available for re-interpretation or noise reduction using different routines.Please cite the original research article when using this dataset
Growth of kyanite and Fe-Mg chloritoid in Fe2O3-rich high-pressure–low-temperature metapelites and metapsammites: A case study from the Massa Unit (Alpi Apuane, Italy)
No full textChloritoid and kyanite coexist in metapelites from the high-pressure/low-temperature Massa Unit in the Alpi Apuane metamorphic complex (Northern Apennines, Italy). The composition of chloritoid is extremely variable throughout the Massa Unit. Fe-chloritoid occurs in association with hematite-free, graphite-bearing schists, whereas strongly zoned Fe-Mg chloritoid is found with hematite and kyanite. We investigated the effect of different bulk Fe2O3 contents in controlling chloritoid composition through phase equilibria modelling of four selected samples, representative of the different chloritoid-bearing parageneses found in the Massa Unit. The ferric iron content, measured through wet chemical titration, ranges from 0 (graphite-chloritoid schist) to 73% of the total iron (hematite-chloritoid schist). We show that Mg-rich chloritoid compositions and stability of kyanite at greenschist to blueschist facies conditions can be reproduced in the MnO-Na2O-K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2-O (MnNKFMASHTO) chemical system only considering the presence of significant amounts of ferric iron as part of the bulk composition. The stabilization of kyanite at lower grade is directly linked to the presence of Fe2O3, which renders the reactive bulk rock composition effectively enriched in Al2O3 with respect to Fe and Mg. We also document that high Fe2O3 contents exacerbate the effect of chloritoid fractionation, producing strongly zoned Fe-Mg-chloritoid grains. Finally, the P-T modelling of the Massa Units performed in this study allows, for the first time, the recognition of a two-stage evolution at peak conditions, with an earlier pressure peak (1.2-1.3 GPa at 350-400 & DEG;C), and a later thermal peak (0.7-1.1 GPa at 440-480 & DEG;C), compatible with subduction, underthrusting and exhumation of the Adria continental margin during growth of the Northern Apennine orogenic wedge
Using exergy to analyze the sustainability of an urban area
No full textThe extended exergy analysis method, taking into account the mean life time cycle of building, has been applied to evaluate
the sustainability of an urban area. The impact of the emissions due to the life cycle of the buildings has been evaluated. Two
thermodynamic indexes, gI and gII showing, respectively, the first and second law efficiency of buildings, have been proposed
as thermodynamic indexes. The applied methodology provides a single thermodynamics environmental criterion for the
selection of technological alternatives, strategies and designs that produce lower environmental impacts connected to higher
exergy indexes gII
Geology of the Northern Apennines nappe stack on eastern Elba (Italy): new insights on the Neogene orogenic evolution of the Northern Tyrrhenian Sea
Get PDFWe document the tectonic and metamorphic evolution of thrust nappes of the eastern island of Elba. The area exposes a natural cross section of the Northern Apennines hinterland, from the metamorphic basement units to the overlying continent- and ocean-derived nappes. We integrated mapping, analysis of structures and microstructures, and the interpretation of drill core logs with lithostratigraphic, metamorphic, and geochronological constraints, producing a novel geological map of eastern Elba (1:5’000 scale). We show that the area experienced polyphase Oligocene–Pliocene contractional tectonics marked by in-sequence and out-of-sequence thrusting accompanied by folding and overprinted by faulting in the Pliocene. Magmatism occurred during contraction with post-magmatic thrusting ultimately coupling HP-LT and LP-HT units. Drill core logs allow for the first time the reconstruction of the N-dipping character of the Zuccale Fault, which represents the youngest (late Miocene–early Pliocene) large-scale structure in the area
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
High-P (P = 1.5–1.8 GPa) blueschist from Elba: Implications for underthrusting and exhumation of continental units in the Northern Apennines
No full textThe Acquadolce Subunit on the Island of Elba, Italy, records blueschist facies metamorphism related to the Oligocene–early Miocene stages of continental collision in the Northern Apennines. The blueschist facies metamorphism is represented by glaucophane- and lawsonite-bearing metabasite associated with marble and calcschist. These rock types occur as lenses in a schistose complex representing foredeep deposits of early Oligocene age. Detailed petrological analyses on metabasic and metapelitic protoliths, involving mineral and bulk-rock chemistry coupled with P–T and P–T–X(Fe2O3) pseudosection modelling using PERPLE_X, show that the Acquadolce Subunit recorded nearly isothermal exhumation from peak pressure–temperature conditions of 1.5–1.8 GPa and 320–370°C. During exhumation, peak lawsonite- and possibly carpholite- or stilpnomelane-bearing assemblages were overprinted and partially obliterated by epidote-blueschist and, subsequently, albite-greenschist facies metamorphic assemblages. This study sheds new light on the tectonic evolution of Adria-derived metamorphic units in the Northern Apennines, by showing (a) the deep underthrusting of continental crust during continental collision and (b) rapid exhumation along ‘cold’ and nearly isothermal paths, compatible with syn-orogenic extrusion
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Fluid-Assisted Strain Localization in Quartz at the Brittle/Ductile Transition
Get PDFA mylonitic quartzite with conjugate and synthetic shear bands was investigated by Electron Backscatter Diffraction and optical microscopy to obtain insights on recrystallization mechanisms and strain localization in quartz at plastic to semibrittle conditions close to the brittle-ductile transition. The mylonitic quartzite deformed during late Miocene thrusting coeval with contact metamorphism in the high-strain domains of the Calamita Schists (Elba Island, Italy). Mylonitic deformation occurred from amphibolite to lower greenschist facies conditions during cooling of the aureole. Dynamic recrystallization, dominated by the activity of dislocation creep by prism slip, produced recrystallized quartz layers mantling relic large quartz porphyroclasts. Under decreasing temperature and fluid-rich conditions, quartz porphyroclasts acted as relatively rigid bodies and fractured along synthetic and conjugate C′ shear bands. Shear bands developed along kinematically favored orientations, just locally assisted by weak crystallographic planes in quartz. Fracturing along shear bands was assisted by cataclasis and fluid infiltration enhancing fracture propagation and healing by recrystallization and authigenesis of new quartz and phyllosilicate grains. The process enhanced the propagation of and strain localization in shear bands, with the development of bands of weak phyllosilicates. Furthermore, we observed the development of a c axis preferred orientation (CPO) related to dissolution and precipitation of new grains with their c axis oriented parallel to shear bands. This study highlights the importance of the interplay between brittle and crystal-plastic processes and fluid ingress in the semibrittle regime to understand deformation partitioning and strain localization
Partial melting and strain localization in metapelites at very low-pressure conditions: The northern Apennines magmatic arc on the Island of Elba, Italy
Get PDFStructural and microstructural analyses and phase equilibria modeling of migmatitic amphibolite-facies metapelites from the late Carboniferous Calamita Schists, on the Island of Elba, Italy, show how the interplay between partial melting and regional (far-field) deformation assisted deformation at very shallow (P ≤ 0.2 GPa) crustal levels. Partial melting was caused by the heat supplied by an underlying late Miocene intrusion (Porto Azzurro pluton) and occurred by biotite continuous melting. The produced melt remained in situ in patches, likely experienced limited migration in stromatic migmatites, and crystallized as a K-feldspar + plagioclase + quartz assemblage. Deformation in the presence of melt occurred by melt-enhanced grain boundary sliding, producing well-foliated high-strain zones with weak evidence of subsolidus deformation at the microscale where the original melt was present. Melt crystallization caused strain hardening and forced subsolidus deformation into localized mylonitic shear zones. The localized character of retrograde deformation was likely determined by the heterogeneous distribution/ingress of fluids in the aureole that locally assisted strain localization, enhancing dislocation creep and reaction softening
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