146 research outputs found
Crystal chemistry of barian titanian phlogopite from a lamprophyre of the gargano promontory (Apulia, Southern Italy)
This study is focused on a barian titanian phlogopite found in an alkaline ultramafic dyke transecting Mesozoic limestones of the Gargano Promontory (Apulia, Italy). The rock containing the barian titanian phlogopite, an olivine-clinopyroxene-rich lamprophyre with nepheline and free of feldspars, has been classified as monchiquite. The present study combines chemical analyses, single crystal X-ray diffraction and Raman spectroscopy. Chemical variations suggest that the entry of Ba into the phlogopite structure can be explained by the exchange Ba + Al = K + Si. The crystal structure refinement indicates that the Ti uptake is consistent with the Tiâoxy exchange mechanism. The structural parameters associated with the oxy substitution mechanism are extremely enhanced and rarely reported in natural phlogopite: (a) displacement of M2 cation toward the O4 site (~0.7); (b) M2 octahedron bond-length distortion (~2.5); (c) very short c cell parameter (~10.14 Ă
). Raman analysis showed most prominent features in the 800â200 cmâ1 region with the strongest peaks occurring at 773 and 735 cmâ1. Only a weak, broad band was observed to occur in the OH-stretching region. As concerns the origin of the barian titanian phlogopite, the rock textural features clearly indicate that it crystallized from pockets of the interstitial melt. Here, Ba and Ti enrichment took place after major crystallization of olivine under fast-cooling conditions, close to the dyke margin
Late Palaeozoic tectonics in Central Mediterranean: a reappraisal
A revision of late Palaeozoic tectonics recorded in Tuscany, Calabria and Corsica is here presented. We propose that, in
Tuscany, upper Carboniferous-Permian shallow-marine to continental sedimentary basins, characterized by unconformities
and abrupt changes in sedimentary facies, coal-measures, red fanglomerate deposits and felsic magmatism,
may be related with a transtensional setting where upper-crustal splay faults are linked with a mid-crustal shear zone.
The remnants of the latter can be found in the deep-well logs of Pontremoli and Larderello-Travale in northern and
southern Tuscany respectively. In Calabria (Sila, Serre and Aspromonte), a continuous pre-Mesozoic crustal section
is exposed, where the lower-crustal portion mainly includes granulites and migmatitic paragneisses, together with
subordinate marbles and metabasites. The mid-crustal section, up to 13 km-thick, includes granitoids, tonalitic to
granitic in composition, emplaced between 306 and 295 Ma. They were progressively deformed during retrograde
extensional shearing, with a final magmatic activity, between 295 ± 1 and 277 ± 1 Ma, when shallower dykes were
emplaced in a transtensional regime. The section is completed by an upper crustal portion, mainly formed by a
Palaeozoic sedimentary succession deformed as a low-grade fold and thrust belt, and locally overlaying mediumgrade
paragneiss units. As a whole, these features are reminiscent of the nappe zone domains of the Sardinia Variscan
Orogen. In Corsica, besides the well-known effusive and intrusive Permian magmatism of the âAutochthonousâ
domain, the Alpine Santa Lucia Nappe exposes a kilometer-scale portion of the Permian lower to mid-crust, exhibiting
many similarities to the Ivrea Zone. The distinct Mafic and Granitic complexes characterizing this crustal domain
are juxtaposed through an oblique-slip shear zone named Santa Lucia Shear Zone. Structural and petrological data
witness the interaction between magmatism, metamorphism and retrograde shearing during Permian, in a temperature
range of c. 800â400 °C. We frame the outlined paleotectonic domains within a regional-scale, strainâpartitioned,
tectonic setting controlled by a first-order transcurrent/transtensional fault network that includes a westernmost fault
(Santa Lucia Fault) and an easternmost one (East Tuscan Fault), with intervening crustal domains affected by extensional
to transtensional deformation. As a whole, our revision allows new suggestions for a better understanding of
the tectonic framework and evolution of the Central Mediterranean during the late Palaeozoic
Permeability and hydraulic condictivity of faulted micashist in the Eastern Elba Island exhumed geothermal system (Tyrrhenian sea, Italy): insights from Cala Stagnone
Estimating values of permeability (k), ef cient porosity (P) and hydraulic conductivity (K) by analysing eld outcrops as analogue of geothermal reservoirs, is a timely theme useful for predictions during geothermal ex- ploration programs. In this paper we present a methodology providing k, P and K values, based on geomet- ric analysis of quartz-tourmaline faults-vein arrays hosted in micaschist exposed in south-eastern Elba Island (Tuscan Archipelago, Italy), considered as the analogue of rock hosting the so-called âdeep reservoirâ in the Larderello geothermal eld. The methodology is based on the integration among structural geology, uid inclu- sions results and numerical analyses. Through a detailed structural mapping, scan-lines and scan-boxes analy- ses, we have reconstructed three superposed faulting events, developed in an extensional setting and framed in the Neogene evolution of inner Northern Apennines. Geometrical data of the fault-veins array were processed by reviewing the basic parallel-plate-model-equation for k evaluation. Fluid inclusion analyses provided those salinity and pressure-temperature values necessary for de ning density and viscosity of the parent geothermal uids. Then, permeability, density and viscosity were joined to get hydraulic conductivity (K). Permeability is estimated between 5 Ă 10â 13 and 5 Ă 10â 17 m2 with variations among the different generation of faults, while the hydraulic conductivity is encompassed between 1.31 Ă 10â 8 and 2.4 Ă 10â 13 m/s. The obtained permeabil- ity and hydraulic conductivity values are comparable with those from several geothermal areas, and in particular from the Larderello geothermal eld. The main conclusion is that the proposed integrated approach provides a reliable methodology to obtain crucial values, normally obtained after drilling, for developing numerical ow models of geothermal uid path in active geothermal systems by eld and laboratory analyses of analogue, ex- humed, geothermal systems
Healthcare professionalsâ perspectives on the use of PCSK9 inhibitors in cardiovascular disease: an in-depth qualitative study
Aims Injectable medicines such as PCSK9 inhibitors are increasingly used to manage risk factors for cardiovascular events with little information around the perceptions of healthcare professionals (HCPs) on the administrative and clinical practicalities. The aim was to identify the facilitators and barriers on the use of injectable therapies with cardiovascular benefits through interviews with HCPs.Methods and results Qualitative interviews were conducted in the UK (London and Leeds) and Italy (Rome and Milan) in 2021. Coding was undertaken using NVivo and thematic analysis performed. A total of 38 HCPs were interviewed, 19 in each country composing of physicians (n = 18), pharmacists (n = 10), nurses (n = 9), and pharmacy technician (n = 1). Four themes emerged: (i) clinicians' previous experiences with injectable therapies, (ii) challenges with patients' behaviours and beliefs, (iii) clinicians' knowledge of injectable therapies and therapeutic inertia, and (iv) organizational and governance issues. The behaviour and beliefs from HCPs focused on facilitating behaviour change as well as the poor interdisciplinary working and collaboration. Therapeutic inertia was raised where physicians either lacked awareness of injectable therapies or were unwilling to prescribe them. The importance of facilitating patient education on injection techniques was highlighted, while organizational and governance issues identified the lack of guidance to inform practice. Clear pathways are required to identify those who were eligible for injectable therapies as well as on how injectables should be prescribed.Conclusion If medicine optimization is to be achieved, there need to be structured processes in place to identify eligible patients and the development of educational material.Graphical Abstrac
Patients' perceptions on the facilitators and barriers using injectable therapies in dyslipidaemia: An empirical qualitative descriptive international study
Background: Injectable medicines are increasingly used to manage abnormal levels of lipids, which is a major risk factor for cardiovascular events. Enhancing our understanding of patients' perceptions of these injectables, can inform practice with the aim of increasing uptake and medication adherence. Aim: To explore patient's experiences of using injectables and to identify potential facilitators and barriers to using injectable therapies in dyslipidaemia. Design: A qualitative descriptive study using semi-structured interviews was conducted with patients who were using injectables to manage their cardiovascular conditions. Methods: A total of 56 patients, 30 from the United Kingdom and 26 from Italy, were interviewed online from November 2020 to June 2021. Interviews were transcribed and schematic content analysis performed. Results: Four distinct themes emerged from interviews with patients and caregivers: (i) Their behaviours and personal beliefs; (ii) Knowledge and education about injectable medication; (iii) Clinical skills and previous experiences and (iv) Organizational and governance. Participants expressed initial fears such as needle phobia, and their concerns about commencing therapy were compounded by a lack of accessible information. However, patients' pre-existing knowledge of lipid lowering medication, previous experience with statins and history of adverse side effects informed their decision-making regarding using injectables. Organization and governance-related issues were primarily around the distribution and management of medication supply within primary care, and the lack of a standardized clinical support monitoring system. Conclusion: Changes are needed in clinical practice to better educate and support patients to improve the uptake of injectables and optimize their use of these medications in the management of dyslipidaemia. Impact: This study suggests that injectable therapies were acceptable to people with cardiovascular disease. However, healthcare professionals need to play a key role in improving education and providing support to aid patients' decision-making regarding commencing and adhering to injectable therapies. Reporting method: The study adhered to the Consolidated Criteria for Reporting Qualitative Research. Patient or public contribution: There was no patient or public contribution
Late-Proterozoic to Paleozoic history of the peri-Gondwana CalabriaâPeloritani Terrane inferred from a review of zircon chronology
UâPb analyses of zircon from ten samples of augen gneisses, eight mafic and intermediate metaigneous rocks and six metasediments from some tectonic domains along the CalabriaâPeloritani Terrane (Southern Italy) contribute to knowledge of peri-Gondwanan evolution from Late-Proterozoic to Paleozoic times. All samples were equilibrated under amphibolite to granulite facies metamorphism during the Variscan orogeny. The zircon grains of all considered samples preserve a Proterozoic memory suggestive of detrital, metamorphic and igneous origin. The available data fit a frame involving: (1) Neoproterozoic detrital input from cratonic areas of Gondwana; (2) Pan-African/Cadomian assemblage of blocks derived from East and West African Craton; (3) metamorphism and bimodal magmatism between 535 and 579Â Ma, within an active margin setting; (4) rifting and opening of Ordovician basins fed by detrital input from the assembled Cadomian blocks. The Paleozoic basins evolved through sedimentation, metamorphism and magmatism during the Variscan orogeny involving Palaeozoic and pre-Paleozoic blocks. The Proterozoic zircon records decidedly decrease in the high grade metamorphic rocks affected by Variscan pervasive partial melting. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40064-016-1839-8) contains supplementary material, which is available to authorized users
An exposed cross-section of the late Hercynian upper and intermediate continental crust in the Sila nappe (Calabria)
Upper to intermediate levels of
continental crust, as shaped by Late Hercynian
metamorphism and magmatism, are exposed in the
Sila nappe (Calabria, S. Italy) after Tertiary
tectonics. Direct observation of the crustal section
reveals a composite metamorphic block dominated
by low- to high-grade metapelites and meta-arenites,
intruded centrally by granitoids. The average
thickness of granitoids, estimated on cross-sections
and by geobarometry, reaches 9 ± 2 km. Their
composition changes with depth from leucogranite
to tonalite with increasing colour index. The
estimated bulk composition of the Sila nappe is
characterised by higher contents of A1203, REE and
Th and lower contents of CaO and Sr than is typical
of upper continental crust, reflecting abundant
metapelite in the Sila nappe. Comparisons between
metasedimentary rocks from the upper and
intermediate levels indicate that intracrustal
differentiation was determined by anatexis, which
favoured A1203 , REE and Th enrichment in
medium- to high-grade metapelites. Distribution of
REE, Th and Zr was connected to the fate of
monazite and zircon during crustal anatexis. Melting
reactions involved mainly muscovite whereas
biotite, enclosing most accessory phases, often
remained stable in the residue. Consequent passive
enrichment of Th in medium- to high-grade restitic metapelite determined an unusual increase in
radiogenic heat production with depth.
Compositional data suggest a connection between
leucogranite genesis and anatexis of intermediate
crust. The composition of leucogranites is similar to
that of crustal melts generated by muscovite
dehydration melting reactions. The extremely low
concentrations of Sr and Ba and high Rb contents
are comparable with those of Himalayan
leucogranites
Modelling the thermal perturbation of the continental crust after intraplating of thick granitoid sheets: a comparison with the crustal sections in Calabria (Italy)
Thick granitoid sheets represent a considerable percentage of Palaeozoic crus tal sections exposed in Calabria. High thermal gradients are recorded in upper and lower crustal regional metamorphic rocks lying at the roof and base of the granitoids. Ages of peak metamorphism and emplacement
of granitoids are mostly overlapping, suggesting a connection between magma intrusion and low-pressure metamorphism. To analyse this relationship, thermal perturbation following granitoid emplacement has been modelled. The simulation indicates that, in the upper crust, the thermal perturbation
is short-lived. In contrast, in the lower crust temperatures greater than 700°C are maintained for 12 Ma, explaining granulite formation, anatexis and the following nearly isobaric cooling. An even longer perturbation can be achieved introducing the effect of mantle Iithosphere thinning into the
model
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