Valle d’Aosta section of the Sesia Zone: multi-stage HP metamorphism and assembly of a rifted continental margin

The spectrum characteristic of the EMC ranges from eclogites (containing omphacite and/or jadeite, garnet, phengite, glaucophane, zoisite, chloritoid, rutile) to phengite schists, calcschists, and marbles, as well as a variety of orthogneisses. Despite the intense polyphase deformation and HP-metamorphic recrystallization, it is possible in some locations to recognize pre-Alpine characteristics in some of the protoliths. For instance, two types of felsic orthogneiss can be distinguished in the Aosta Valley, one derived from Permian granitoids (with local preservation of intrusive contacts, magmatic inclusions, leucocratic veins and other magmatic structures; Stop 3), the other derived from pre-Variscan leuco-monzogranite, such as the building stone mined at the “Argentera” quarry near Settimo Vittone / Montestrutto (Stop 2; so-called “Verde Argento” contains jadeite, phengite, K-feldspar, quartz). Polycyclic and more rarely monocyclic metasediments contain evidence of a complex Alpine PTDt-evolution, locally including relics of their prograde history from blueschist, one or more stages at eclogite facies. Recent petrochronological studies have dated this HP-evolution of the Sesia Zone in some detail. In the area visited, clear evidence of HP-cycling has been identified in one km-size tectonic slice (Stop 1), but not in adjacent parts of the EMC, indicating “yo-yo tectonics”. Partial retrogression and attendant ductile to brittle deformation of the HP-rocks is evident in one of the outcrops (Stop 4). Apart from the four localities in the Sesia Zone, a final outcrop introduces HP-rocks of the adjacent Piemonte oceanic unit, specifically calc-schists and ophiolite members of the “Zermatt-Saas” zone. The hilltop outcrop (Stop 5) displays foliated antigorite schist with peridotite relics (clinopyroxene, spinel) containing lenses derived from doleritic dykes. These fine-grained metarodingites and the folded veins containing Mg-chlorite and titanoclinohumite within serpentinite once again indicate equilibration under low-temperature eclogite facies conditions. However, these units reached that HP stage more than 20 Ma after the youngest eclogite facies imprint recognized in the Sesia Zone. Despite nearly half a century of intense study in the Sesia Zone, the complex assembly of its HP-terranes and their relation to more external parts of the Western Alps remains incompletely understood. This field guide merely introduces a few of the classic outcrops and discusses some of the critical evidence they contain, but it could not incorporate details on each stage of the evolution recognized so far.

Multiple metamorphic stages within an eclogite-facies terrane (Sesia Zone, Western Alps) revealed by Th-U-Pb petrochronology

Convergent plate margins typically experience a transition from subduction to collision dynamics as massive continental blocks enter the subduction channel. Studies of high-pressure rocks indicate that tectonic fragments are rapidly exhumed from eclogite facies to midcrustal levels, but the details of such dynamics are controversial.To understand the dynamics of a subduction channel we report the results of a petrochronological study from the central Sesia Zone, a key element of the internalWestern Alps.This comprises two polymetamorphic basement complexes (Eclogitic Micaschist Complex and Gneiss Minuti Complex) and a thin, dismembered cover sequence (Scalaro Unit) associated with pre-Alpine metagabbros and metasediments (Bonze Unit). Structurally controlled samples from three of these units (Eclogitic Micaschist Complex and Scalaro-Bonze Units) yield unequivocal petrological and geochronological evidence of two distinct high-pressure stages. Ages (U-Th-Pb) of growth zones in accessory allanite and zircon, combined with inclusion and textural relationships, can be tied to the multi-stage evolution of single samples.Two independent tectono-metamorphic ‘slices’ showing a coherent metamorphic evolution during a given time interval have been recognized: the Fondo slice (which includes Scalaro and Bonze rocks) and the Druer slice (belonging to the Eclogitic Micaschist Complex).The new data indicate separate stages of deformation at eclogite-facies conditions for each recognized independent kilometer-sized tectono-metamorphic slice, between ~85 and 60 Ma, with evidence of intermittent decompression (∆P~0.5 GPa) within only the Fondo slice. The evolution path of the Druer slice indicates a different P-T-time evolution with prolonged eclogite-facies metamorphism between ~85 and 75Ma. Our approach, combining structural, petrological and geochronological techniques, yields field-based constraints on the duration and rates of dynamics within a subduction channel.

Geological map of the Scalaro Valley – Sesia Zone (Italian Western Alps)

In the Sesia Zone (Italian Western Alps), slivers of continental crust characterised by an Alpine high-pressure imprint are intermingled with abundant mafic rocks and Mesozoic metasediments. An extensive study of the central Sesia Zone was undertaken to identify and reconstruct the lithological setting of the mono-cyclic sediments of the Scalaro Unit. A new geological map (1:5000) and schematic cross sections across the Scalaro Unit and the adjoining Eclogitic Micaschist Complex are presented here. In order to delimit the size and shape of the mono-metamorphic unit and understand its internal geometry with respect to the poly-metamorphic basement, an integrated approach was used. Linking observations and data across a range of scales, from kilometres in the field down to petrological and chronological data obtained at micrometre scale, we define for the first time the real size and internal geometry of the Scalaro Unit, as well as its large-scale structural context.

Stability of Contour Augmentation and Esthetic Outcomes of Implant Supported Single Crowns in the Esthetic Zone. 3-Year Results of a Prospective Study With Early Implant Placement Post Extraction

Early implant placement is one of the treatment options after tooth extraction. Implant surgery is performed after a healing period of 4 to 8 weeks and combined with a simultaneous contour augmentation using the guided bone regeneration technique to rebuild stable esthetic facial hard- and soft-tissue contours.

Genome-wide DNA profiling of marginal zone lymphomas identifies subtype-specific lesions with an impact on the clinical outcome

Marginal zone B-cell lymphomas (MZLs) have been divided into 3 distinct subtypes (extranodal MZLs of mucosa-associated lymphoid tissue [MALT] type, nodal MZLs, and splenic MZLs). Nevertheless, the relationship between the subtypes is still unclear. We performed a comprehensive analysis of genomic DNA copy number changes in a very large series of MZL cases with the aim of addressing this question. Samples from 218 MZL patients (25 nodal, 57 MALT, 134 splenic, and 2 not better specified MZLs) were analyzed with the Affymetrix Human Mapping 250K SNP arrays, and the data combined with matched gene expression in 33 of 218 cases. MALT lymphoma presented significantly more frequently gains at 3p, 6p, 18p, and del(6q23) (TNFAIP3/A20), whereas splenic MZLs was associated with del(7q31), del(8p). Nodal MZLs did not show statistically significant differences compared with MALT lymphoma while lacking the splenic MZLs-related 7q losses. Gains of 3q and 18q were common to all 3 subtypes. del(8p) was often present together with del(17p) (TP53). Although del(17p) did not determine a worse outcome and del(8p) was only of borderline significance, the presence of both deletions had a highly significant negative impact on the outcome of splenic MZLs.

"Device landing zone" calcification, assessed by MSCT, as a predictive factor for pacemaker implantation after TAVI

After trans-catheter aortic valve implantation (TAVI), the need for postinterventional pacemaker (PM) implantation can occur in as many as 10-50% of cases, but it is not yet clear, how this need can be predicted. The aim of this study was to assess the possible predictive factors of post TAVI PM implantation based on Computed Tomography (CT) measured aortic valve calcification and its distribution.

Correlation of Device landing zone calcification and acute procedural success in patients undergoing transcatheter aortic valve implantations with the self-expanding CoreValve prosthesis

The aim of this study was to assess the influence of amount and distribution of calcifications of the aortic valve and the left ventricular outflow tract on the acute procedural outcome of patients undergoing transcatheter aortic valve implantation (TAVI).