Petrology, geochemistry and origin of the Sierra de Baza ophiolites (Betic Cordillera, Spain)

In this work we present for the first time a petrological-geochemical and genetic study of the Sierra de Baza ophiolites, which represent one of the ophiolitic occurrences of the Betic Cordillera (Southern Spain). They are composed of ultramafic, mafic and sedimentary rocks, largely affected both by ocean floor and polyphasic metamorphism during the Alpine orogeny. Ultramafic rocks are serpentinized lherzolites and harzburgites, whereas the metabasites are meta-gabbros and meta-basalts. On the whole, Sierra de Baza ophiolites show striking geochemical similarities with those from other Betic occurrences, as well as with other Tethyan ophiolites of the Western Mediterranean (Calabria, Internal and External Ligurides, Platta, Corsica and Western Alps). In particular, metabasites show petrological and geochemical features similar to the E-MORB magmatism of the Atlantic Ridge between 45 and 63ºN generated under ultra-slow spreading ridge conditions. This process originated a strip of few hundreds km of ocean floor at the western end of the Tethys, located SE of the Iberian-European margin during the Mesozoic. The inversion of the stress regime in the European-Iberian and African geodynamics, starting from the Late-Middle Cretaceous, caused subduction and metamorphism in the eclogite facies of oceanic slices that were partially exhumed on the continental margin, forming the Betic Ophiolites. These ophiolites were disarticulated and dismembered as a result of the shift towards SW of the Alboran continental block, progressively separated from the AlKaPeCa (Alboran, Kabilias, Peloritani, Calabria) microplate, finally occupying their current position in the Betic Internal Zones

Using HoloLens Mixed Reality to research correlations between language and movement: a case study

Communication can be defined as the understanding and exchanging of meaningful messages. The role of communication is central to the lives of human beings as, everyday, we use language to interact with the world around us. Linguistic skills play a fundamental role in this scenario and Language Disorders (LD) are impairments that limit the processing of linguistic information. Early and accurate identification of LD is thus essential to promote lifelong learning and well-being. From an evolutionary perspective, some human language constructs evolved from an ancestral motor system and share the same neural pathways in the Broca’s area of the brain. This suggests a correlation between action and language. If such a relationship is well established and reliable, it would be possible to use the former as a marker of the latter. The hypothesis of our work, in a nutshell, is that movement can be a predictor of language. To study this correlation, we developed C(H)o(L)ordination, a Mixed Reality (MR) application for HoloLens 2. The application offers several activities based on visual stimuli involving motor movements, which tap on the same skills needed to perform some language tasks. We performed an exploratory study with N=22 users to test the application usability and user experience. The results suggest that C(H)o(L)ordination is a usable and powerful tool to gather insights on the ongoing debate about language evolution and language disorders

Subduction-related hybridization of the lithospheric mantle revealed by trace element and Sr-Nd-Pb isotopic data in composite xenoliths from Tallante (Betic Cordillera, Spain)

Ultramafic xenoliths are rarely found at convergent plate margins. A notable exception is in the Betic Cordillera of southern Spain, where the eruption of xenolith-bearing alkaline basalts during the Pliocene post-dated the Cenozoic phase of plate convergence and subduction-related magmatism. Mantle xenoliths of the monogenetic volcano of Tallante display extreme compositional heterogeneities, plausibly related to multiple tectono-magmatic episodes that affected the area. This study focuses on two peculiar composite mantle xenolith samples from Tallante, where mantle peridotite is crosscut by felsic veins of different size and mineralogy, including quartz, orthopyroxene, and plagioclase. The veins are separated from the peridotite matrix by an orthopyroxene-rich reaction zone, indicating that the causative agents were alkali-rich hydrous silica-oversaturated melts, which were likely related to recycling of subducted continental crust components. The present study reports new and detailed major and trace elements and Sr-Nd-Pb analyses of the minerals in the composite Tallante xenoliths that confirm the continental crust derivation of the metasomatic melts, and clarifies the mode in which subduction-related components are transferred to the mantle wedge in orogenic areas. The particular REE patterns of the studied minerals, as well as the variation of the isotopic ratios between the different zones of the composite xenoliths, reveal a complex metasomatic process. The distribution of the different elements, and their isotope ratios, in the studied xenoliths are controlled by the mineral phases stabilised by the interaction between the percolating melts and the peridotitic country rock. The persistence of marked isotopic heterogeneities and the lack of re-equilibration suggest that metasomatism of the sub-continental lithospheric mantle occurred shortly before the xenolith exhumation. In this scenario, the studied xenoliths and the metasomatic processes that affected them may be representative of the mantle sources of mafic potassic to ultrapotassic magmas occurring in post-collisional tectonic settings

Petrogenesis and tectonic significance of IAT magma-types in the Hellenide ophiolites as deduced from the Rhodiani ophiolites (Pelagonian zone, Greece)

The Rhodiani ophiolites are represented by two tectonically superimposed ophiolitic units: the “lower” Ultramafic unit and the “upper” Volcanic unit, both bearing calcareous sedimentary covers. The Ultramafic unit consists of mantle harzburgites with dunite pods and chromitite ores, and represents the typical mantle section of supra-subduction zone (SSZ) settings. The Volcanic unit is represented by a sheeted dyke complex overlain by a pillow and massive lava sequence, both including basalts, basaltic andesites, andesites, and dacites. Chemically, the Volcanic unit displays low-Ti affinity typical of island arc tholeiite (IAT) ophiolitic series from SSZ settings, having, as most distinctive chemical features, low Ti/V ratios (b20) and depletion in high field strength elements and light rare earth elements. The rare earth element and incompatible element composition of the more primitive basaltic andesites from the Rhodiani ophiolites can be successfully reproduced with about 15% non-modal fractional melting of depleted lherzolites, which are very common in the Hellenide ophiolites. The calculated residua correspond to the depleted harzburgites found in the Rhodiani and Othrys ophiolites. Both field and chemical evidence suggest that the whole sequence of the Rhodiani Volcanic unit (from basalt to dacite) originated by low-pressure fractional crystallization under partially open-system conditions. The modelling of mantle source, melt generation, and mantle residua carried out in this paper provides new constraints for the tectono-magmatic evolution of the Mirdita–Pindos oceanic basin

Petrogenesis and tectono-magmatic significance of basalts and mantle peridotites from the Albanian-Greek ophiolites and sub-ophiolitic melanges. New constraints for the Triassic-Jurassic evolution of the Neo-Tethys in the Dinaride sector

The Albanide–Hellenide ophiolites and related ophiolitic mélanges include eight different types of volcanic and subvolcanic rocks: 1) Triassic, within-plate alkaline rocks (WPB); 2) Triassic high-Ti mid-ocean ridge basalts showing enriched compositions (E-MORB); 3) Triassic and Jurassic high-Ti mid-ocean ridge basalts showing normal compositions (N-MORB); 4) Jurassic basalts with geochemical features between MORB and island arc tholeiites; hereafter defined as medium-Ti basalts (MTB); 5) Jurassic low-Ti, island arc tholeiitic (IAT) rocks; 6) Jurassic very low-Ti (boninitic) rocks; 7) Jurassic backarc basin basalts and basaltic andesites (BABB); 8) Triassic and Jurassic calc-alkaline rocks (CAB). The geochemical and petrogenetic features of these rock-types, as well as the results from REE modelling of mantle sources, primary melt generation, and mantle residua indicate that they have formed in distinct tectonic settings within an oceanic environment. Both Triassic and Jurassic N-MORBs primary magmas derived from ~ 10 to 20% partial melting of a primitive asthenosphere, whereas Triassic alkaline WPB basalts originated from low degrees of partial melting of an OIB-type mantle source and were most likely erupted in seamounts. Triassic E-MORBs originated from ~ 12% partial melting of a primitive asthenosphere influenced by the OIB-type component. The residual MORB mantle is represented by depleted lherzolites, which are commonly found in the Albanide–Hellenide ophiolites. Mid Jurassic MTB and IAT primary magmas derived from ~ 10% and 10–20% partial melting of the MORB residual mantle, respectively with the variable addition of subduction components and were erupted in an intra-oceanic, supra-subduction zone setting. The residual mantle associated with these magmatic events is represented by harzburgites. Mid Jurassic boninitic primary magmas may have originated either from 10 to 20% partial melting of the MTB and IAT residual mantle or from ~ 30% partial melting of the MORB residual mantle. In both cases, the depleted mantle sources were enriched in light rare earth elements (LREE) by subduction-derived fluids. The extremely depleted harzburgites, which are widespread in the Albanide–Hellenide ophiolites, are interpreted as the residual mantle associated with boninite formation. Mid-Late Jurassic CABs originated from ~ 15 to 20% partial melting of a depleted peridotite mantle significantly enriched in Th and LREE by subduction-derived fluids, whereas BABBs originated from 10 to 20% partial melting of a primitive asthenosphere somewhat enriched in Th and LREE by a nearby subduction. Both these rock-types were erupted in a continental arc-backarc setting. The different rock-types of the Albanide–Hellenide ophiolites record the fundamental stages of the Triassic–Jurassic evolution of the Neo-Tethys in the Dinaride sector: from sea-floor spreading, after continental break-up, to intra-oceanic subduction initiation and supra-subduction zone (SSZ) lithospheric accretion