An introduction to orogenic andesites and crustal growth

This chapter provides an overview of the current state of research on orogenic andesites. While their importance as proxies to the evolution of the continental crust has long been recognized, andesite genesis has remained highly controversial with a broader consensus yet to be reached. The controversy is fuelled by the question of whether orogenic andesites are primary melts of slab and mantle materials, or instead derivative products of basaltic mantle melts that differentiate in the overlying crust. These hypotheses are addressed in three sections of the book devoted to slab–mantle processes, the complexities of melt differentiation at crustal levels, and models pertaining to arc crustal growth. We believe that cross-fertilization and discussion among seemingly opposite and irreconcilable hypotheses will smooth the pathway towards a holistic communal model of andesite petrogenesis

The Systematics of Olivine CaO + Cr-Spinel in High-Mg# Arc Volcanic Rocks: Evidence for in-Situ Mantle Wedge Depletion at the Arc Volcanic Front

We investigated the state of the arc background mantle (i.e. mantle wedge without slab component) by means of olivine CaO and its Cr-spinel inclusions in a series of high-Mg# volcanic rocks from the Quaternary Trans-Mexican Volcanic Belt. Olivine CaO was paired with the Cr# [molar Cr/(Cr + Al) *100] of Cr-spinel inclusions, and 337 olivine+Cr-spinel pairs were obtained from 33 calc-alkaline, high-K and OIB-type arc front volcanic rocks, and three monogenetic rear-arc basalts that lack subduction signatures. Olivine+Cr-spinels display coherent elemental and He–O isotopic systematics that contrast with the compositional diversity of the bulk rocks. All arc front olivines have low CaO (0.135 ± 0.029 wt %) relative to rear-arc olivines which have the higher CaO (0.248 ± 0.028 wt %) of olivines from mid-ocean ridge basalts. Olivine 3He/4He–δ18O isotope systematics confirm that the olivine+Cr-spinels are not, or negligibly, affected by crustal basement contamination, and thus preserve compositional characteristics of primary arc magmas. Variations in melt H2O contents in the arc front series and the decoupling of olivine CaO and Ni are inconsistent with controls on the olivine CaO by melt water and/or secondary mantle pyroxenites. Instead, we propose that low olivine CaO reflects the typical low melt CaO of high-Mg# arc magmas erupting through thick crust. We interpret the inverse correlation of olivine CaO and Cr-spinel Cr# over a broad range of Cr# (~10–70) as co-variations of CaO, Al and Cr of their (near) primary host melts, which derived from a mantle that has been variably depleted by slab-flux driven serial melt extraction. Our results obviate the need for advecting depleted residual mantle from rear- and back-arc region, but do not upset the larger underlying global variations of melt CaO high-Mg# arc magmas worldwide, despite leading to considerable regional variations of melt CaO at the arc front of the Trans-Mexican Volcanic Belt

Crustal recycling by subduction erosion in the central Mexican Volcanic Belt

Recycling of upper plate crust in subduction zones, or ‘subduction erosion’, is a major mechanism of crustal destruction at convergent margins. However, assessing the impact of eroded crust on arc magmas is difficult owing to the compositional similarity between the eroded crust, trench sediment and arc crustal basement that may all contribute to arc magma formation. Here we compare Sr–Nd–Pb–Hf and trace element data of crustal input material to Sr–Nd–Pb–Hf–He–O isotope chemistry of a well-characterized series of olivine-phyric, high-Mg# basalts to dacites in the central Mexican Volcanic Belt (MVB). Basaltic to andesitic magmas crystallize high-Ni olivines that have high mantle-like 3He/4He = 7–8 Ra and high crustal δ18Omelt = +6.3–8.5‰ implying their host magmas to be near-primary melts from a mantle infiltrated by slab-derived crustal components. Remarkably, their Hf–Nd isotope and Nd/Hf trace element systematics rule out the trench sediment as the recycled crust end member, and imply that the coastal and offshore granodiorites are the dominant recycled crust component. Sr–Nd–Pb–Hf isotope modeling shows that the granodiorites control the highly to moderately incompatible elements in the calc-alkaline arc magmas, together with lesser additions of Pb- and Sr-rich fluids from subducted mid-oceanic ridge basalt (MORB)-type altered oceanic crust (AOC). Nd–Hf mass balance suggests that the granodiorite exceeds the flux of the trench sediment by at least 9–10 times, corresponding to a flux of ⩾79–88 km3/km/Myr into the subduction zone. At an estimated thickness of 1500–1700 m, the granodiorite may buoyantly rise as bulk ‘slab diapirs’ into the mantle melt region and impose its trace element signature (e.g., Th/La, Nb/Ta) on the prevalent calc-alkaline arc magmas. Deep slab melting and local recycling of other slab components such as oceanic seamounts further diversify the MVB magmas by producing rare, strongly fractionated high-La magmas and a minor population of high-Nb magmas, respectively. Overall, the central MVB magmas inherit their striking geochemical diversity principally from the slab, thus emphasizing the importance of continental crust recycling in modern solid Earth relative to its new formation in modern subduction zones

COVID Feel Good-An Easy Self-Help Virtual Reality Protocol to Overcome the Psychological Burden of Coronavirus

Background: Living in the time of the COVID-19 means experiencing not only a global health emergency but also extreme psychological stress with potential emotional side effects such as sadness, grief, irritability, and mood swings. Crucially, lockdown and confinement measures isolate people who become the first and the only ones in charge of their own mental health: people are left alone facing a novel and potentially lethal situation, and, at the same time, they need to develop adaptive strategies to face it, at home. In this view, easy-to-use, inexpensive, and scientifically validated self-help solutions aiming to reduce the psychological burden of coronavirus are extremely necessary. Aims: This pragmatic trial aims to provide the evidence that a weekly self-help virtual reality (VR) protocol can help overcome the psychological burden of the Coronavirus by relieving anxiety, improving well-being, and reinforcing social connectedness. The protocol will be based on the 'Secret Garden' 360 VR video online (www.covidfeelgood.com) which simulates a natural environment aiming to promote relaxation and self-reflection. Three hundred sixty-degree or spherical videos allow the user to control the viewing direction. In this way, the user can explore the content from any angle like a panorama and experience presence and immersion. The 'Secret Garden' video is combined with daily exercises that are designed to be experienced with another person (not necessarily physically together), to facilitate a process of critical examination and eventual revision of core assumptions and beliefs related to personal identity, relationships, and goals. Methods: This is a multicentric, pragmatic pilot randomized controlled trial involving individuals who experienced the COVID-19 pandemic and underwent a lockdown and quarantine procedures. The trial is approved by the Ethics Committee of the Istituto Auxologico Italiano. Each research group in all the countries joining the pragmatic trial, aims at enrolling at least 30 individuals in the experimental group experiencing the self-help protocol, and 30 in the control group, over a period of 3 months to verify the feasibility of the intervention. Conclusion: The goal of this protocol is for VR to become the 'surgical mask' of mental health treatment. Although surgical masks do not provide the wearer with a reliable level of protection against the coronavirus compared with FFP2 or FFP3 masks, surgical masks are very effective in protecting others from the wearer's respiratory emissions. The goal of the VR protocol is the same: not necessarily to solve complex mental health problems but rather to improve well-being and preserve social connectedness through the beneficial social effects generated by positive emotions

ANTaging: a Research Protocol for Active Navigation Training with Virtual Reality in Mild Cognitive Impairment

Navigation is a multimodal process that requires the active computation of cognitive and bodily cues along with external environmental information. Indeed, according to the embodied cognition framework, the body and the environment build our cognitive representation of the space. This view is supported by findings in the aging population where the decline of bodily information accounts for the deficits in spatial navigation. Consequently, it is crucial to develop innovative rehabilitation solutions in aging that require the active use of bodily and cognitive processing of the space and its elements. Mild cognitive impairment is a geriatric syndrome considered to be a transitional stage between normal aging and dementia. Consequently, it is a preferred time window to administer cognitive rehabilitation programs that could slow down cognitive deterioration. In the current paper, the ANTaging protocol will be presented in its three-step studies: pilot testing, usability study, and proof-of-concept trial

A Ribosomal Misincorporation of Lys for Arg in Human Triosephosphate Isomerase Expressed in Escherichia coli Gives Rise to Two Protein Populations

We previously observed that human homodimeric triosephosphate isomerase (HsTIM) expressed in Escherichia coli and purified to apparent homogeneity exhibits two significantly different thermal transitions. A detailed exploration of the phenomenon showed that the preparations contain two proteins; one has the expected theoretical mass, while the mass of the other is 28 Da lower. The two proteins were separated by size exclusion chromatography in 3 M urea. Both proteins correspond to HsTIM as shown by Tandem Mass Spectrometry (LC/ESI-MS/MS). The two proteins were present in nearly equimolar amounts under certain growth conditions. They were catalytically active, but differed in molecular mass, thermostability, susceptibility to urea and proteinase K. An analysis of the nucleotides in the human TIM gene revealed the presence of six codons that are not commonly used in E. coli. We examined if they were related to the formation of the two proteins. We found that expression of the enzyme in a strain that contains extra copies of genes that encode for tRNAs that frequently limit translation of heterologous proteins (Arg, Ile, Leu), as well as silent mutations of two consecutive rare Arg codons (positions 98 and 99), led to the exclusive production of the more stable protein. Further analysis by LC/ESI-MS/MS showed that the 28 Da mass difference is due to the substitution of a Lys for an Arg residue at position 99. Overall, our work shows that two proteins with different biochemical and biophysical properties that coexist in the same cell environment are translated from the same nucleotide sequence frame

predictive precision medicine towards the computational challenge

The emerging fields of predictive and precision medicine are changing the traditional medical approach to disease and patient. Current discoveries in medicine enable to deepen the comprehension of diseases, whereas the adoption of high-quality methods such as novel imaging techniques (e.g. MRI, PET) and computational approaches (i.e. machine learning) to analyse data allows researchers to have meaningful clinical and statistical information. Indeed, applications of radiology techniques and machine learning algorithms rose in the last years to study neurology, cardiology and oncology conditions. In this chapter, we will provide an overview on predictive precision medicine that uses artificial intelligence to analyse medical images to enhance diagnosis, prognosis and treatment of diseases. In particular, the chapter will focus on neurodegenerative disorders that are one of the main fields of application. Despite some critical issues of this new approach, adopting a patient-centred approach could bring remarkable improvement on individual, social and business level

The role of subducted sediments in the formation of intermediate mantle-derived magmas from the Northern Colombian Andes

Unraveling the sources and processes that produce intermediate continental arc volcanoes is still a challenge for geoscientists. To address this problem, here we use comprehensive geochemical and isotopic data from Nevado del Santa Isabel and Cerro Machín volcanoes in the North Volcanic Province of Colombia, and from oceanic sediments sampled outboard the Colombian continental margin. Volcanoes along this province have been influenced by the subduction of a compositionally contrasting sedimentary column constituted by a carbonate-rich pelagic layer overlain by a clay-and-apatite-rich hemipelagic unit. The studied volcanoes exhibit the high Mg# (~60) and calc-alkaline affinities that are typical of continental arcs but display unusually high and contrasting Th(U)/La, Nb/Ta and Dy/Yb ratios and isotopic compositions. We argue that the geochemical variations within and among these volcanoes are not controlled by differentiation or crustal contamination of a parental basaltic magma but formed by melting of different kinds of subducted sedimentary materials detached from the slab as buoyantly rising diapirs at various depths. This model accounts for the reworking of refractory carbonates into arc magmatism and suggests that the geochemical diversity of the North Volcanic Province is mainly controlled by the nature of the subduction inputs and their exhumation pathways within the mantle wedge. © 201