Structural characterization and K–Ar illite dating of reactivated, complex and heterogeneous fault zones: lessons from the Zuccale Fault, Northern Apennines

We studied the Zuccale Fault (ZF) on Elba, part of the Northern Apennines, to unravel the complex deformation history that is responsible for the remarkable architectural complexity of the fault. The ZF is characterized by a patchwork of at least six distinct, now tightly juxtaposed brittle structural facies (BSF), i.e. volumes of deformed rock characterized by a given fault rock type, texture, colour, composition, and age of formation. ZF fault rocks vary from massive cataclasite to foliated ultracataclasite, from clay-rich gouge to highly sheared talc phyllonite. Understanding the current spatial juxtaposition of these BSFs requires tight constraints on their age of formation during the ZF lifespan to integrate current fault geometries and characteristics over the time dimension of faulting. We present new K–Ar gouge dates obtained from three samples from two different BSFs. Two top-to-the-east foliated gouge and talc phyllonite samples document faulting in the Aquitanian (ca. 22 Ma), constraining east-vergent shearing along the ZF already in the earliest Miocene. A third sample constrains later faulting along the exclusively brittle, flat-lying principal slip surface t

K+ accumulation and clearance in the calyx synaptic cleft of type I mouse vestibular hair cells

Vestibular organs of Amniotes contain two types of sensory cells, named Type I and Type II hair cells. While Type II hair cells are contacted by several small bouton nerve terminals, Type I hair cells receive a giant terminal, called a calyx, which encloses their basolateral membrane almost completely. Both hair cell types release glutamate, which depolarizes the afferent terminal by binding to AMPA post-synaptic receptors. However, there is evidence that non-vesicular signal transmission also occurs at the Type I hair cell-calyx synapse, possibly involving direct depolarization of the calyx by K+ exiting the hair cell. To better investigate this aspect, we performed whole-cell patch-clamp recordings from mouse Type I hair cells or their associated calyx. We found that [K+] in the calyceal synaptic cleft is elevated at rest relative to the interstitial (extracellular) solution and can increase or decrease during hair cell depolarization or repolarization, respectively. The change in [K+] was primarily driven by GK,L, the low-voltage-activated, non-inactivating K+ conductance specifically expressed by Type I hair cells. Simple diffusion of K+ between the cleft and the extracellular compartment appeared substantially restricted by the calyx inner membrane, with the ion channels and active transporters playing a crucial role in regulating intercellular [K+]. Calyx recordings were consistent with K+ leaving the synaptic cleft through postsynaptic voltage-gated K+ channels involving KV1 and KV7 subunits. The above scenario is consistent with direct depolarization and hyperpolarization of the calyx membrane potential by intercellular K+

A New Albite Microanalytical Reference Material from Piz Beverin for Na, Al and Si Determination, and the Potential for New K-Feldspar Reference Materials

Determination of alkali elements is important to Earth scientists, yet suitable and reliable microanalytical reference materials are lacking. This paper proposes a new albite reference material and evaluates the potential for future K-feldspar reference materials. The proposed Piz Beverin albite reference material from Switzerland yields a homogeneous composition at the centimetre- to micrometre-scale for Si, Al and Na with \u3c 2000 μg g-1 total trace elements (mostly heterogeneously distributed Ca, K and Sr). EPMA and LA-ICP-MS measurements confirm a composition of 99.5(2)% albite component, which is supported further by bulk XRF measurements. A round robin evaluation involving nine independent EPMA laboratories confirms its composition and homogeneity for Si, Al and Na. In addition, a set of five distinct clear K-feldspar samples was evaluated as possible reference materials. The first two crystals of adular and orthoclase yield unacceptable inhomogeneities with \u3e 2% relative local variations of Na, K and Ba contents. The three other investigated sets of K-feldspar crystals are yellow sanidine crystals from Itrongay (Madagascar). Despite distinct compositions, EPMA confirms they are each homogeneous at the centimetre to micrometre scale for Si, Al and K and have no apparent inclusions; further investigation to find larger amounts of these materials is therefore justified

Fossil micrometeorites from Monte dei Corvi: Searching for dust from the Veritas asteroid family and the utility of micrometeorites as a palaeoclimate proxy

We searched late Miocene sedimentary rocks in an attempt to recover fossil micrometeorites derived from the Veritas asteroid family. This study was motivated by the previous identification of a pronounced 3He peak (4-5x above background) within marine sediments with ages between ∼8.5–6.9 Ma ago (Montanari et al., 2017. GSA Bulletin, 129:1357–1376). We processed 118.9 kg of sediment from the Monte dei Corvi beach section (Italy), the global type-section for the Tortonian epoch (11.6–7.2 Ma). Samples were collected both before and within the 3He peak. Although a small number of iron-rich (I-type) fossil micrometeorites were recovered from each horizon studied (Ntotal = 20), there is no clear difference between the pre- and intra- 3He peak samples. All micrometeorites are compositionally similar, and three out of five horizons yielded similar abundances and particle sizes. Micrometeorites extracted from sediments at the base of the 3He peak were exclusively small (ø 3He values were relatively large (ø 3He signature combined with the absence of fossil micrometeorites or extraterrestrial spinels (Boschi et al., 2019, Spec. Pap. Geol. Soc. Am. 542:383–391) unambiguously related to the Veritas event suggests that the Veritas family is composed of highly friable materials that rarely survive on the sea floor to become preserved in the geological record. Our data supports the existing hypothesis that the Veritas asteroid family is an aqueously altered carbonaceous chondrite parent body, one that contains minimal native metal grains or refractory Cr-spinels. The low yield of fossil micrometeorites at Monte dei Corvi is attributed to loss of particles by dissolution whilst they resided on the sea floor but also due to high sedimentation rates leading to dilution of the extraterrestrial dust flux at this site. As with other fossil micrometeorite collections (e.g. Cretaceous chalk [Suttle and Genge, EPSL, 476:132–142]) the I-type spherules have been altered since deposition. In most particles, both magnetite and wüstite remain intact but have been affected by solid state geochemical exchange, characterised by partial leaching of Ni, Co and Cr and implantation of Mn, Mg, Si and Al. In some particles Mn concentrations reach up to 16.6 wt%. Conversely, in some micrometeorites wüstite has been partially dissolved, or even replaced by calcite or ankerite. Finally, we observe evidence for wüstite recrystallisation, forming a second generation of magnetite. This process is suggested to occur by oxidation during residence on the seafloor and has implications for the use of fossil I-type micrometeorites as a potential proxy for probing Earth’s upper atmospheric composition (oxidative capacity) in the geological past. However, solutions to the limitations of post-depositional recrystallisation are suggested. Fossil I-type spherules remain a potential tool for palaeo-climatic studies

Unexpected impairment of INa underpins reentrant arrhythmias in a knock-in swine model of Timothy syndrome

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Construction and evolution of a granitic complex in the upper crust: geometrical and geochemical constraints on the emplacement of the Valle Mosso pluton (Ivrea Zone, Southern Alps, Italy)

The focus of this study is on the magmatic evolution of the Valle Mosso pluton, a granitic body intruded at intermediate to upper crustal levels into the rocks of the Alpine basement of the Ivrea-Verbano Zone and Serie dei Laghi, shortly after the end of Variscan orogeny. The Valle Mosso pluton has been recognized as an integral part of a magmatic system (Quick et al., 2009), which during the lower Permian developed through the continental crust up to the surface and caused explosive rhyolitic volcanism that eventually led to the formation of a >15 km diameter caldera. This granitic body was tilted as a consequence of Alpine orogeny and thus exposes both its deepest and shallower portions. This peculiar feature, shared worldwide by just a few other similar intrusions, if combined together with its characteristic geological framework makes the Valle Mosso pluton a rather unique case study. In fact, the opportunity to study a continuous vertical section of a granitic intrusion genetically linked to coeval volcanic deposits has substantial implications, both in the understanding of the mechanisms that rule granitic bodies’ emplacement in the upper crust and in the comprehension of the volcanic-plutonic connection. By means of detailed geological mapping, the internal structure of the pluton and the relationship with its host rocks have been determined. The pluton has been divided into six granitic petrofacies, based on textural criteria derived from up-to-date scientific literature on the mapping of granite terranes. The combination of field data with thin section examination have led to the compilation of a geological map of the Pluton at 1:15.000 scale, which is equipped with cross section and schemes that help the reader focus on the geometry and internal variability of the intrusive body. Laboratory analyses have been carried out alongside fieldwork, with the aim of defining the intrusion’s geochemical features, which are essential to the compilation of a petrogenetic model that could attest for the heterogeneity of the granitic body. Whole-rock analyses of over 100 granitic rock samples have been performed trough X-ray fluorescence (XRF) to determine major-element compositions, at least 25 selected samples have been analysed by means of ICPMS for their trace element contents and 5 more underwent mass spectrometry (TIMS) to determine their Sr isotopic ratio. In addition to whole-rock analyses, selected minerals (Qz, Plg, Ho, Bt) belonging to the deepest facies of the Valle Mosso pluton have been analysed by means of microprobe. These data obtained through ion microprobe analyses have been used to perform thermometric and barometric calculations, which purpose was to set constraints on the intrusion crystallization conditions. Starting from the data collected in both field and laboratory, an incremental growth of the Valle Mosso pluton is hypothesized through the emplacement of several sill-like (high aspect-ratio) granitic bodies inside the upper crust; they partially interacted and gradually evolved by means of fractional crystallization processes. Based on field evidence, an intrusion emplacement mechanism that considers both floor subsiding and roof lifting (together with the detachment of roof pendants) is favoured for the composite Valle Mosso pluton. In addition to discussing the processes that led to the generation and emplacement of the granitic magma, based on the collected data, there is also room to speculate on a possible plutonic record of rejuvenation of largely solidified magma chamber preserved inside the Valle Mosso intrusion. In fact, a particular porphyry granite found inside the pluton discloses mineral phenocrysts (Qz, Plg, Kf) that show clear petrographic and geochemical evidence for thermal and compositional disequilibrium, which are similarly found in crystals belonging to the coeval volcanic deposits of the Permian caldera. The collected data seem to indicate a possible link between reheating evidence in granitic rocks and volcanic events

Structure and petrography of the Valle Mosso pluton, Sesia Magmatic System, Southern Alps

5noThe Valle Mosso pluton (VMP) is a Permian granitic body intruded at intermediate to upper crustal levels in the rocks of the pre-Alpine basement of the Ivrea-Verbano Zone and Serie dei Laghi shortly after the end of Variscan orogeny. As a consequence of Triassic to Jurassic rifting and Alpine orogeny, the VMP and surrounding host rocks have been tilted more than 60° from their original Permian polarity. Thus at present day, the VMP offers the rare opportunity to study a roof-to-floor exposure of a granitic pluton, providing insights into pristine geometry of the magma chamber and its relations to the country rocks. This work presents a new drift and solid map of the VMP and its surrounding host rocks at 1:15.000 scale.open accessopenopenTavazzani, Lorenzo; Peres, Stefano; Sinigoi, Silvano; Demarchi, Gabriella; Musumeci, GiovanniTavazzani, Lorenzo; Peres, Stefano; Sinigoi, Silvano; Demarchi, Gabriella; Musumeci, Giovann

Precision medicine: a new era for inner ear diseases

The inner ear is the organ responsible for hearing and balance. Inner ear dysfunction can be the result of infection, trauma, ototoxic drugs, genetic mutation or predisposition. Often, like for Ménière disease, the cause is unknown. Due to the complex access to the inner ear as a fluid-filled cavity within the temporal bone of the skull, effective diagnosis of inner ear pathologies and targeted drug delivery pose significant challenges. Samples of inner ear fluids can only be collected during surgery because the available procedures damage the tiny and fragile structures of the inner ear. Concerning drug administration, the final dose, kinetics, and targets cannot be controlled. Overcoming these limitations is crucial for successful inner ear precision medicine. Recently, notable advancements in microneedle technologies offer the potential for safe sampling of inner ear fluids and local treatment. Ultrasharp microneedles can reach the inner ear fluids with minimal damage to the organ, collect μl amounts of perilymph, and deliver therapeutic agents in loco. This review highlights the potential of ultrasharp microneedles, combined with nano vectors and gene therapy, to effectively treat inner ear diseases of different etiology on an individual basis. Though further research is necessary to translate these innovative approaches into clinical practice, these technologies may represent a true breakthrough in the clinical approach to inner ear diseases, ushering in a new era of personalized medicine