Search

This paper sheds light on syn-exhumation, pervasive cataclastic processes occurred on competent serpentinites of a metaophiolitic sub-unit of the Voltri Massif. The reported data highlight the importance of the compositional and structural heterogeneities within the ophiolite-bearing exhumation channels, since the observed pervasive cataclastic processes affected only the more competent rock bodies of the metaophiolitic unit, giving origin to a serpentinite breccia, named as Acquasanta Breccia. This breccia is cemented by random-oriented chrysotile fibers that give rise to a very uncommon microstructure, as highlighted by optical microscopy, Micro-Raman spectroscopy, SEM-EDS and TEM investigations. The Acquasanta Breccia underwent a sequence of syn-exhumation tectonic events, accompanied by the onset of different generations and types of chrysotile, which occur both in veins and in the rock matrix. The breccia records the intermediate and late stages of the exhumation of the Voltri meta-ophiolites, which occurred after the development of the retrograde greenschist-facies foliation and before the late shallower faulting events.

Magnesiobeltrandoite-2N3S, ideally Mg6Al20Fe3+2 O38(OH)2, is a new member of the högbomite supergroup of minerals. It occurs in magnesian chloritites of a metamorphosed layered mafic complex in the Etirol-Levaz continental slice, middle Valtournenche, Aosta Valley, Italy. Magnesiobeltrandoite-2N3S grows in a fine-grained chlorite matrix associated as inclusions to relict pre-Alpine hercynite spinels and dolomite in cm-to dm-long darker boudins, which are cut by corundum + clinochlore ± dolomite veins. It occurs as subhedral to euhedral black crystals (∼50–400 mm), dark reddish-brown in thin section. It shows dark brown streak and vitreous lustre. It is brittle, with no cleavage observed and uneven fracture. Mohs hardness ≈ 6–61⁄2. Dcalc = 3.93 g · cm3It shows no fluorescence under UV radiation and no cathodoluminescence. The mineral is optically uniaxial (–) with an estimated mean refractive index of ca. 1.80. Pleochroism is weak with e = deep reddish brown (along c axis) and v = reddish brown (⊥ c). Absorption is E > O. The Raman spectrum shows a weak and strongly polarized broad OH-characteristic absorption centred at 3364 cm1Electron microprobe analysis combined with Synchrotron Mössbauer source spectrometry yielded the following empirical formula based on 40 anions per formula unit (pfu) [Al18.36Mg3.96Fe2+2:52Fe3+2:08Ti0.56Cr0.40Zn0.06V3+0:03Mn0.02]S28O38(OH)2The ideal formula is Mg6Al20Fe3+2 O38(OH)2.The eight strongest lines in the X-ray powder diffraction pattern are [dobs/Å (I) (hkl)]: 2.858 (42) (1 1 0), 2.735 (51) (1 0 7), 2.484 (46) (0 1 8), 2.427 (100) (1 1 5), 1.568 (29) (1 2 8), 1.514 (30) (0 2 12), 1.438 (42) (2 0 13), and 1.429 (72) (2 2 0). The crystal structure of magnesiobeltrandoite-2N3S [P3m1, a = 5.7226(3), c = 23.0231(9) Å, V = 652.95(5) Å3] was refined from X-ray single-crystal data to R1 = 0.022; it is isostructural with magnesiohögbomite-2N3S.

Sliding knots can be performed in many situations during an arthroscopic procedure. Their use is possible in quite all conditions w here a tissue should be fixed using a suture as in rotator cuff tear repair or Bankart repair. Many knots are described and performed by arthroscopic surgeons. Aim of this chapter is to describe the principles of sliding knots and create a practical guide for surgeons to learn in an easy way the most famous knots. This guide could help youn g surgeons to learn the basic knots and expert surgeons to learn new techniques. The most famous knots have been described using a step-by-step description and images, to make them more reproducible

Purpose: Age-related modifications of tendons, such as reduced tenocyte proliferation and modified extracellular matrix (ECM) turnover, have been previously described, but results are often incomplete and discordant. The aim of this study was to investigate, using morphological and molecular methods, the effect of ageing on human tendons and tenocytes, especially focusing on the collagen turnover pathways, in order to understand how the ageing process could influence tendon biology and structure. Methods: Morphological analysis was performed on fragments from human semitendinosus and gracilis tendons harvested from 10 adult (mean age 41.8 ± 13.3 years) and 6 aged healthy patients (mean age 72.7 ± 7.0 years) by haematoxylin and eosin, Sirius red and Alcian blue staining. The expression of genes and proteins involved in collagen turnover and focal adhesions was assessed by real-time PCR, slot blot and zymography in cultured tenocytes. Cytoskeleton arrangement was studied by immunofluorescence and cell migration by wound healing assay. Results: The structure and composition of ECM in ageing tendons are preserved as well as the expression of genes and proteins involved in collagen turnover pathways. Although morphological analysis revealed that ageing tenocytes tended to an impaired migration potential and that actin filaments are occasionally shorter and randomly distributed, the expression of proteins involved in focal adhesion formation is preserved. Conclusion: Results of this study suggest that the structure of ageing tendons is preserved and that ageing tenocytes maintain their ability for ECM remodelling, supporting the hypothesis that ageing tendons maintain their biomechanical properties. The biological reliability of aged tendons has a clinical relevance, supporting the use of tendon autografts also in the elderly patients. Since the common and successful orthopaedic procedure of anterior cruciate ligament reconstruction using either autografts or allografts i

The purpose of this study was to generate consensus among experienced surgeons on what skills a resident should possess before continuing safe training in the operating room (OR). An online survey of 65 questions was developed and distributed to surgeons in the European community. A total of 216 responded. The survey included 15 questions regarding generic and specific skills; 16 on patient and tissue manipulation, 11 on knowledge of pathology and 6 on inspection of e-anatomical structures; 5 methods to prepare residents; and 12 on specific skills exercises. The importance of each question (arthroscopic skill) was evaluated ranging from 1 (not important at all) to 6 (very important). Chi-square test, respondent agreement, and a qualitative ranking method were determined to identify the top ranked skills (p < 0.05). The top four of general skills considered important were anatomical knowledge, tissue manipulation, spatial perception, and triangulation (all chi-square test > 134, p < 0.001, all excellent agreement > 0.85, and all high priority level). The top ranked 2 specific arthroscopic skills were portal placement and triangulating the tip of the probe with a 30-degree scope (chi-square test > 176, p < 0.001, excellent agreement, and assigned high priority). The online survey identified consensus on skills that are considered important for a trainee to possess before continuing training in the OR. Compared with the Canadian colleagues, the European arthroscopy community demonstrated similar ranking.

Subduction zones modulate the global carbon cycle. Carbon is transported into the mantle by the subducting slab and returned to the surface by degassing at arc volcanoes above the subduction zone(1,2). However, the mechanisms for the transfer of carbon from the subducting slab and sediments into the overlying mantle wedge are poorly understood. Decarbonation-a metamorphic reaction between silicate and carbonate minerals that releases CO(2)-was thought to be the primary mechanism. Yet, thermodynamic models show that decarbonation occurs at much greater pressures and temperatures than those found in typical subduction zones(3-6). Carbon should therefore be retained in the slab and transported to great depths in the mantle, rather than supply the arc volcanoes. Here we identify diamonds in ultrahigh-pressure rocks from the Italian western Alps that have an oceanic origin. We assess the geochemistry of diamond-bearing fluid inclusions and find that they contain bicarbonate, carbonate and sulphate ions, silica monomers, and crystals of carbonate and silicate. This fluid geochemistry indicates that carbon was released from the slab at relatively shallow depths through dissolution, not decarbonation. We conclude that dissolution, driven by fluids released from the subducted slab, is an important mechanism for the transfer of carbon into the mantle and ultimately back into the atmosphere, helping to balance the carbon flux.

We report on Alpine metamorphic and fluid inclusion evolution of a polyphase rodingite occurrence within the Bellecombe antigorite-serpentinite, exposed in the Piemonte zone of Aosta Valley, NW Italy. Fine-grained rodingitic rocks, derived from a protolith of basaltic dike(s), are cross-cut by a network of at least six vein generations, consisting of chlorite, diopside, and grossular garnet (Type I), andradite-grossular garnet + diopside (Type II), andradite-rich garnet + chlorite (Type III), grossular-rich garnet (Type IV), vesuvianite (Type V), and chlorite (Type VI). The fine-grained rodingite and associated veins reveal a tectono-metamorphic history similar to that of the hosting serpentinite and characterized by an earlier high pressure metamorphism, followed by decompression/re-equilibration under greenschist facies conditions and by final cooling. The fluid inclusion study, performed on primary fluid inclusions in vesuvianite from Type V veins and on secondary fluid inclusions in andradite-rich garnet from Type III veins, revealed that at P = 0.22 GPa and T = 400 degrees C, an H2-bearing (XH2 = 0.010) brine (6 wt.% CaCl2 + 6 wt.% NaCl) with traces of CH4 (XCH4 = 0.002 was introduced into the rock. This fluid had a composition compatible with the Ca-rich H2-bearing, reducing aqueous solutions reported from the serpentinization front. These data point to an important event of rodingitization, probably triggered by hydration of metamorphic olivine, during the late greenschist facies Alpine evolution that was probably triggered by hydration of metamorphic olivine.

The ultrahigh-pressure pyrope whiteschists from the Brossasco-Isasca Unit of the Southern Dora-Maira Massif represent metasomatic rocks originated at the expense of post-Variscan granitoids by the influx of fluids along shear zones. In this study, geochemical, petrological and fluid-inclusion data, correlated with different generations of pyrope-rich garnet (from medium, to very-coarse-grained in size) allow constraints to be placed on the relative timing of metasomatism and sources of the metasomatic fluid. Geochemical investigations reveal that whiteschists are strongly enriched in Mg and depleted in Na, K, Ca and LILE (Cs, Pb, Rb, Sr, Ba) with respect to the metagranite. Three generations of pyrope, with different composition and mineral inclusions, have been distinguished: (i) the prograde Prp I, which constitutes the large core of megablasts and the small core of porphyroblasts; (ii) the peak Prp II, which constitutes the inner rim of megablasts and porphyroblasts and the core of small neoblasts; and (iii) the early retrograde Prp III, which locally constitutes an outer rim. Two generations of fluid inclusions have been recognized: (i) primary fluid inclusions in prograde kyanite that represent a NaCl-MgCl(2)-rich brine (6-28 wt% NaCl(eq) with Si and Al as other dissolved cations) trapped during growth of Prp I (type-I fluid); (ii) primary multiphase-solid inclusions in Prp II that are remnants of an alumino-silicate aqueous solution, containing Mg, Fe, alkalies, Ca and subordinate P, Cl, S, CO(3)2-, LILE (Pb, Cs, Sr, Rb, K, LREE, Ba), U and Th (type-II fluid), at the peak pressure stage. We propose a model that illustrates the prograde metasomatic and metamorphic evolution of the whiteschists and that could also explain the genesis of other Mg-rich, alkali-poor schists of the Alps. During Alpine metamorphism, the post-Variscan metagranite of the Brossasco-Isasca Unit experienced a prograde metamorphism at HP conditions (stage A: similar to 1.6 GPa and < 600 de

Rotator cuff tear is a common cause of shoulder pain and disability, and arthroscopic repair is a frequently performed procedure. To improve results and reduce failure rate of this surgery, biological solutions to enhance tendon repair are being investigated. Mesenchymal stem cells contribute in creating a suitable microenvironment for tissue repair, and therefore therapeutic use of tendon tissue-specific stem cells in clinical practice is one of the most promising challenges in regenerative medicine approaches to rotator cuff repair. The aim of this article is to revise the current literature on tendon-derived stem cells for rotator cuff repair. Identification and characterization of a reservoir of progenitor cells in human shoulder periarticular tissues has been successfully confirmed by different authors. The first animal studies on the healing potential of these mesenchymal stem cells showed encouraging results. No clinical trials have been published yet. Rigorous preclinical translational studies are needed to ensure safety and efficacy of stem cells–based treatments before routine use in clinical practice.

Minerals, fluid inclusions and stable isotopes have been studied in ultrahigh-pressure (UHP) OH-rich topaz-kyanite quartzites from Hushan (west of Dongai), in southern Sulu (China). The quartzites underwent a metamorphic evolution characterized by a peak stage (3.5 GPa and 730-820 degrees C) with the anhydrous assemblage coesite+kyanite I, followed by an early near-isothermal decompression stage (2.9 GIa and 705-780 degrees C) with growth of kyanite II, muscovite, and OH-rich topaz, and by decompression-cooling stages, represented by paragonite (1.9 GPa and 700-780 degrees C) and pyrophyllite (0.3 GPa and 400 degrees C) on kyanite (I and II) and OH-rich topaz, respectively. These rocks may exhibit unusually low delta O-18 and delta D values acquired before undergoing UHP metamorphism. Five distinct fluid generations are recognized. Type I.: concentrated peak solutions rich in Si, Al, and alkalis, present within multiphase inclusions in kyanite I Type II: CaCl2-rich brines present during the growth of early retrograde OH-rich topaz. Type III, IV, and V- late aqueous fluids of variable salinity, and rare CO2 present during amphibolite- and late greenschist-facies conditions. A number of conclusions may be drawn from these relationships that have an effect on fluid evolution in deeply subducted continental rocks. (1) At a pressure of about 3.5 GPa alkali-alumino-silicate aqueous solutions, with compositions intermediate between H2O fluid and melt (H2O > 25 and <= 50 wt %) evolved from quartzites, probably generated by dehydration reactions. (2) During early decompression stages, at the transition from URP to high-pressure (2.9 GPa) conditions, brines Of external origin with higher water contents (82 wt % H2O) initiated the growth of OH-rich topaz and muscovite. (3) The subsequent decompression, at P < 2 GPa, was defined by a limited circulation of NaCl aqueous fluids, and CO2 infiltration. Overall, fluid inclusions and stable isotopes highlight a metamorphic fluid-rock

The ultrahigh-pressure (UHP) Maowu Ultramafic Complex (Dabie Shan, China) is hosted by coesite-bearing gneisses. Textural and geochemical data demonstrate that garnet–orthopyroxenites within the ultramafic complex derive from garnet–harzburgite precursors that have been metasomatised at peak UHP conditions (4.0±1.0 GPa, 750±50 °C) by the addition of a silica- and incompatible trace element-rich fluid phase (hydrous melt), sourced from the associated crustal rocks. This metasomatism produced poikilitic orthopyroxene with high LREE and Ni contents and inclusion-rich garnet porphyroblasts. Solid polyphase primary inclusions within peak metamorphic garnet display negative crystal shapes and constant volume ratios of infilling mineral phases. Experimental homogenisation of these inclusions at conditions close to the estimated metamorphic peak demonstrates that the polyphase inclusions derive from trapped solute-rich aqueous fluids. The trace element characteristics of the experimentally re-homogenised inclusions include high LREE contents, a pronounced enrichment in LILE, with spikes of Cs, Ba, Pb and high U/Th. The investigated UHP garnet–orthopyroxenites from Maowu represent a natural laboratory to constrain the trace element transfer from the subducted crust to the mantle wedge at sub-arc depths. The observed textures and chemical characteristics provide evidence for the infiltration of a felsic hydrous melt into garnet–peridotite, a circumstance comparable to expected interaction of sediment-derived melts with mantle wedge peridotites in subduction zones. The SiO2 and Al2O3 component of the hydrous melt reacted with olivine to form replacive orthopyroxene and new garnet. The neoblastic orthopyroxene is able to accommodate some of the LREE, whereas the H2O and LILE component of the melt were partitioned into a residual aqueous fluid phase. Remnants of such an aqueous fluid were trapped in the garnet and formed the polyphase inclusions. The trace element pattern of the

Release of metamorphic fluids within the slab and/or from the slab to the mantle wedge in subduction environments can produce important metasomatic effects. Ultrahigh-pressure (UHP) metasomatised rocks represent ideal materials to study the element exchange at pressures corresponding to sub-arc depths in subduction zones. We present a petrologic and geochemical study of eclogites (s.l.) from the Dabie Mountains (China). The investigated samples were collected in the North Dabie Complex, where eclogite-facies rocks are significantly overprinted by granulite-facies metamorphism and partial melting. The studied eclogites are included in meta-lherzolitic bodies, which are in turn hosted by leucocratic gneisses. The textural relations among the various rock-forming minerals enabled us to identify several re-crystallisation stages. The peak (UHP) paragenesis consists of garnet, clinopyroxene and rutile. UHP garnet and clinopyroxene display oriented inclusions of polycrystalline rods of rutile+ilmenite and of albite, K–Ba-feldspar and quartz, respectively. Garnet and clinopyroxene are both rimmed by an inclusion free zone that formed after the peak, still at high-pressure conditions. Such optical zoning does not correspond to a difference in major element concentrations between garnet core and rim. This observation provides evidence that the major element composition of garnet was reset during exhumation, thus preventing thermobarometric determination of peak metamorphic conditions. Further decompression is documented by the formation of limited ilmenite+amphibole and granulite-facies coronas consisting of clinopyroxene, orthopyroxene, plagioclase and amphibole around garnet. In order to investigate the stability of observed mineral parageneses, a series of reconnaissance piston cylinder synthesis experiments were carried out in an identical bulk composition. The experimental study indicates that the peak metamorphic paragenesis is stable at P∼3.5 GPa and T≥750–800 °C. The

Combined petrographic, minerochemical, fluid inclusion, and stable isotope studies have been carried out on phengite-kyanite-epidote (Phe-Ky-Ep) eclogites from Hushan and Qinglongshan (Donghai area, UHP Sulu orogen, China) to unravel their metamorphic evolution and fluid-rock interaction. A complex metamorphic evolution, from coesite-eclogite (P = 3.5-4.0 GPa and T = 840 +/- 50 degrees C) to greenschist facies conditions (P congruent to 0.2 GPa and T congruent to 350 degrees C), through quartz-eclogite and HT amphibolite-facies conditions, was recognized. The associated fluids are aqueous and show a progressive change in salinity and composition, reflecting different metamorphic stages. Stable isotope data confirm that, prior to subduction, the Sulu eclogite protolith experienced a meteoric-hydrothermal alteration, and indicate that during metamorphic evolution the rocks recrystallized without pervasive fluid infiltration

Primary multiphase solid (MS) inclusions without preserved fluid are found within peak minerals in kyanite quartzite topaz and kyanite-phengite-epidote eclogite from Donghai area (Su-Lu terrane). Typical mineral association in inclusions is: paragonite + muscovite + anhydrite +/- corundum +/- "alunite-type" sulphate +/- zircon +/- calcite +/- chlorite +/- SiO2 +/- barite +/- pyrite +/- apatite in quartzites, and paragonite + rutile + apatite +/- amphibole +/- Zn-staurolite +/- magnetite +/- plagioclase +/- zircon +/- pyrite +/- "alunite-type" sulphate +/- Zn-Mg-Fe-Al-Ti spinel in eclogites. On the basis of the fluid inclusion textures and of the daughter-phase assemblage, calculated fluid composition is as follows: in quartzites 24 wt.% SiO2, 30 wt.% Al2O3, 9 Wt.% CaO, 5 wt.% K2O, 3 wt.% Na2O, 11 Wt-% SO3, 18 wt.% H2O, with traces of TiO2, Fe2O3, FeO, MgO, BaO, P2O5, Cl-, F, and (CO3)(2-), and in eclogites 26 wt.% SiO2, 21 wt.% TiO2, 20 wt.% Al2O3, 2 wt.% MgO, 4 wt.% FeO, 6 wt.% Fe2O3, 7 wt.% CaO, 3 wt.% NaO, 3 Wt-% P2O5, 7 wt.% H2O, 1 wt.% Cl, and traces of ZnO, MnO, K2O, SO3, and F. Originally trapped chloride-poor aqueous fluids contained very high amounts - in the order of tens of wt.% - of Si4+, Al3+, and Ti4+. Solute species reflect the chemical composition of the host rocks: Mg2+, Fe2+, Ti4+, P5+, and Na+, are abundant in the fluids present in eclogites, while fluids are enriched in Al3+, K+, Na+, (SO4)(2-),(CO3)(2-) in quartzites. We propose that multiphase solid inclusions represent remnants of high-density supercritical silicate-rich aqueous fluids that were in equilibrium with peak minerals at UHP conditions. These fluids show characters which are transitional between aqueous fluids and silicate melts, and were probably produced by dehydration reactions of the host rocks during the latest stages of subduction. (c) 2005 Published by Elsevier B.V.