Tilocalar Norte lava flow and Tilocalar Sur small-lava shield are two monogenetic volcanoes of intermediate composition located in the Central Andes formed between 460 and 730 f 50 ka. These volcanoes allow us to constrain the lifespan of the effusive activity and investigate the magmatic processes underlying monogenetic volcanism. This study provides new 40Ar/39Ar and geochemical data to constrain the eruptive history. It also establishes the magmatic processes based on their lifespans or transitions, and understands the volcanic hazards associated with these small-volume magmatic systems. Tilocalar Norte was dated in the present work at 684 f 143 ka, while Tilocalar Sur from basal west flow was dated at 693 f 38 ka, defining an eruption interval within 9 f 2 kyr at 692 f 37 ka (2 sigma errors). The initial magma batches of Tilocalar Norte and Tilocalar Sur originate from the same source, derived from magma-crust interaction with the lower crust (suitable for garnet growth) under increasing pressure, and from depleted and/or dehydrated sources with partial melting and delamination of the lower crust. However, these batches were separated en route to the surface. They underwent different degrees of fractionation, with the least fractionated batch reaching the surface first (Tilocalar Sur) and the most fractionated batch last (Tilocalar Norte). Our results provide quantitative constraints on monogenetic volcanism regarding the transition of their emplacement, with implications for risk mitigation in the event of future lava flow eruptions that could pose a threat to nearby infrastructure (villages and mining operations).

Flank collapses are one of the most significant destructive processes in long-lived volcanoes, resulting in debris avalanche deposits (DADs), which shed light on volcanic landslide sizes, physical characteristics, and transport mechanisms. Here, three DADs with a hummocky topography recognized at Ollagüe, a long-lived and mainly effusive volcano in the Central Volcanic Zone of the Andes, are investigated in detail. We combine fieldwork and morphometric analysis to characterize the DADs, constrain the destabilization and trigger factors, and determine the effect of the substrate on the emplacement of the debris avalanches. In general, hummocks decrease in size, volume, and competence with distance. The low rate of size decrease, large runout distances, and spatial distribution of hummocks suggest a high mobile flow in proximal parts (recorded by a non-depositional belt lacking hummocks) followed by a more distal sector marked by rapid deceleration of the avalanche, directly attributable to the combined effects of topography and substrate nature, with a passage from a shallow paleolake to a dry and non-competent evaporitic substrate (salt flat) in correspondence with the Carcote Basin. This study provides further insights into the effect of weak ductile substrates on debris avalanche transport and emplacement mechanisms, with DADs from Ollagüe revealing a complex dynamic interplay between the evolution of the volcano and the surrounding landscape, reflected by fluctuations in the level of the Carcote paleolake.

Correlation of ignimbrite units at polygenic calderas is mandatory for the reconstruction of caldera-forming events and proper identification of their eruption dynamics. However, ignimbrites erupted at different times from the same caldera can display similarities in composition and lithology that can hamper proper correlation of outcrops across the caldera structure. Here, high-resolution paleomagnetic and 40Ar/39Ar data are used along with stratigraphic evidence to address and resolve the relationships between two ignimbrites associated with the Latera caldera (Grotte di Castro and Onano Formations, Vulsini Volcanic District, Central Italy). These were characterized at 32 paleomagnetic sites and eleven 40Ar/39Ar sampling sites encompassing proximal and distal facies. Overall, the paleomagnetic directions of the two ignimbrites are statistically indistinguishable whereas single-grain 40Ar/39Ar ages of sanidine and leucite crystals show systematic preservation of pre-eruptive ages with sectorial variations closely controlled by eruption dynamics, yet with a neatly defined common juvenile (syn-eruptive) age at 205 ka. The data show that the two ignimbrites are the product of a single event, here renamed the "Grotte di Castro-Onano" eruption, representing the largest and latest caldera-forming stage of the Latera system. The sectorial preservation of pre-eruptive 40Ar/39Ar ages across the depositional sequence is interpreted to reflect the extraction processes with selective (re)mobilization of magma batches associated to piston collapse dynamics. Coupling paleomagnetism with 40Ar/39Ar dating is shown to be a key step in such cases for successful resolution of individual caldera-forming events at the millennial scale.

Since the Earth’s topography is shaped by both tectonic and climatic processes, measuring land surface elevation variations through time is of critical importance for the investigation of the multiple interactions between mountain building (orogenic) processes and long-term climate change. With a total surface area of over 5 million km2, an average elevation of 5000 m and 14 peaks over 8000 m, the Tibetan Plateau (TP) and adjacent Himalaya are particularly well suited to this research, as many models attempt to explain the growth of these high elevation regions in the context of the continental collision between India and Asia and their feedback on the Asian climate. However, the evolution of surface elevation (paleoaltimetry), whilst essential, is still elusive in the Himalaya. A number of published paleoaltimetric data hinges on the relationship between the stable isotopic composition of precipitation (δ18O and δD) and altitude. However, these methods, based on the stable isotopic composition of carbonates and phylosilicates, do not provide both δ18O and δD values and involve the use of an isotope exchange equation to calculate the composition of paleoprecipitation. To avoid such calculation, we use a method developed at LGL-TPE, which directly measure the isotopic composition (δ18O and δD) of paleoprecipitation trapped in fluid inclusions of hydrothermal quartz veins. We measured the δ18O and δD of fluid inclusions in quartz veins within the Main Central Thrust shear zone in the Jajarkot klippe (Central Himalaya, Nepal). The δ18O of fluid inclusions varies between -3.69‰ and -9.01‰ and the δD between -43.11‰ and -74.24‰, which are consistent with meteoric water compositions. Stable isotope analysis were coupled with Ar-Ar geochronology on hydrothermal white micas that co-crystallized with quartz and indicates an age of 24.7 ± 0.2 Ma for vein formation. Taken together, these data allow us to calculate a mean elevation of the Central Himalaya of 2771 +286/-403 m at the end of the Oligocene, a period for which no previous paleoaltimetric data are available. Although already significant 25 Myr ago, the mean elevation of the Central Himalaya was nevertheless lower than the average elevation of the present topography (~5000 m), which formed at least ~16 Myr ago (e.g., Gébelin et al., 2013, Melis et al., 2023). Collectively, our data as well as previous paleoaltimetric studies provide a valuable contribution to the assessment of deformation models for the Himalayan range.

We performed experiments to constrain the effects of sulphur and oxygen fugacities on magma chamber and outgassing conditions of the La Palma 2021 eruption. Based on a series of controlled experiments on basanitic products carried out at 1040 degrees C and 200 MPa, we show that sulphur addition affects the stabilities of amphibole and olivine, in particular at high fO(2) and elevated S contents which together inhibit amphibole crystallization. We also show that the overriding control on S systematics is oxygen fugacity, with melts capable of dissolving from 1000 up to 8000 ppm S, depending on fO(2). Increasing the bulk S content increases the S content of the silicate melt up to similar to 2000 ppm for fO(2) < NNO + 2, and 7000-8000 ppm at higher fO(2). Further increase in dissolved S is prevented by the buffering effects of either sulphide at low fO(2) or anhydrite at high fO(2). Modelling shows that the observed CO2/SO2 and H2O/SO2 ratios of volcanic gas emissions during the eruption imply a pre-existing >5 wt% exsolved fluid in the reservoir, with fS(2) at similar to 0.1 MPa at fO(2) above NNO. Our work confirms that basaltic magmas may coexist with a significant amount of excess fluid which in turn holds an important part of the sulphur budget emitted to the atmosphere.

The East African Rift is one of Earth's largest continental landforms. It is recognized as a critical region for understanding hominin evolution yet has also undergone important transformation through ongoing tectonic and volcanic activity. An understanding of the interplay of rift kinematics, magma genesis and geomorphic evolution requires firm geochronology but this has been lacking for much of the East African Rift. Here we present detailed stratigraphic observations and high-precision 40Ar/39Ar ages for major volcanic units in the Central Main Ethiopian Rift. Our new data identify a volumetrically major episode of explosive volcanism between circa 3.85-3.42 million years ago, after aproximately 5-million years-long quiescence. Four other pulses followed but with intensity and magnitude declining over time. We suggest that the observed temporal clustering and the pulsatory volcanic activity may have influenced environmental conditions in the area, with possible implications for hominin evolution. Five major explosive volcanic pulses in the Main Ethiopian Rift took place in the last four million years with intensity and magnitude declining over time, based on stratigraphic and geochronology data of volcanic units.

Ar-40/Ar-39 ages of phlogopite from kimberlite-hosted mantle xenoliths are commonly older than the kimberlite eruption, despite the fact that argon is supposed not to be retained by phlogopite at temperatures above hydrothermally-derived Ar closure temperatures (<500 degrees C). Combining Molecular Dynamics (MD) with Nudged Elastic Band (NEB) and Transition State Theory (TST), we investigate Ar-40-PVT (Pressure-Volume-Temperature) relationships in pristine, defect-free, phlogopite and show that Ar-40 diffusivity is several orders of magnitude slower than existing estimates with a strong effect of pressure on diffusion rates and retention of Ar-40 at mantle conditions. These results imply to fundamentally revise residence- and transit-time estimates based on Ar kinetics in phlogopite assuming simple diffusive relaxation during upwelling. When accounting for pressure, Ar-40 retention trends in phlogopite predict substantially slower kimberlite ascent rates than documented by independent chronometers, indicating that Ar-40 resetting during ascent in phlogopite does not result from simple decompression-driven diffusive relaxation. We argue that Ar-40 remobilization probably involves secondary structural-textural modifications induced by reaction-driven recrystallization or rim overgrowth. These findings have far-reaching consequences in terms of argon isotopic mobility at mantle depths as well as for dating and tracing metasomatic events during crust-mantle interactions in the evolution of the subcontinental mantle.

Evolved alkaline magmas have fuelled renowned large explosive eruptions, including that of Tambora in 1815. Very high sulphur yields to the atmosphere have been suggested for some prominent phonolite–trachyte eruptions, influencing assessments of their potential climatic impacts. However, the implications of alkalinity on volatile abundances in melts remain only partially understood. Here, we draw on available petrological and thermodynamical constraints, accounting for uncertainty in pre-eruptive magma redox state, to quantify pre-eruptive sulphur budgets for several prominent phonolite–trachyte eruptions. We thereby calculate upper limits for suphur yields for the 13 kyr calBP Laacher See eruption (3–15 Tg S), the plinian component of the 39.85 ka Campanian Ignimbrite (2–9 Tg S), and the 1890 calBCE “Avellino” and 79 CE eruptions of Vesuvius. Our findings demonstrate that alkali-rich magmas do not outstrip dacite or rhyolite arc compositions in respect of sulphur abundance and can inform both climate modelling efforts and the search for the eruptions’ signatures in ice core records.

Bimodal magmatism is characteristic of the geodynamic evolution of the Main Ethiopian Rift (MER), which is a reference area for the study of the processes leading to continental break-up before seafloor spreading. There are abundant emissions of basalts and rhyolites, which are in possible parent-daughter relationships. However, the P-T-H2O conditions of production and storage of the basaltic end member remain unclear. Crystallization experiments have been conducted on an alkali basalt from the MER to define its pre-eruptive conditions and shed light on the compositional evolution of derivative liquids and source conditions. The experiments were performed at 100 to 200 MPa, 975 degrees C to 1080 degrees C, varying H2O/CO2 ratios, corresponding to melt water contents of 1 to 5 wt %, at fO(2) slightly lower than the Fayalite-Magnetite-Quartz (FMQ) solid buffer. Comparison between the petrological attributes of the starting rock and the experiments shows that the basaltic magma was stored at 150 to 200 MPa, 1050 +/- 10 degrees C, with 1 to 2 wt % H2O in melt, with fO(2) near FMQ prior to eruption. Geochemical modelling shows that the corresponding mantle source contained about 0.1 wt % H2O, reflecting a metasomatized source. Extensive crystallization of such basalts produces SiO2-rich liquids, which are not yet peralkaline, however. This underscores that extreme fractionation (>90 wt %) is required in order to produce peralkaline derivatives from mildly alkaline basalts. This extreme fractionation and the water-rich nature of the starting basalt readily explain the H2O-rich condition of peralkaline rhyolites that have fueled caldera forming eruptions in the Rift.

The Longmen Shan, eastern and steepest margin of the Tibetan plateau, is often seen as the archetype example of an orogenic system built by crustal channel flow extrusion since the Miocene. This model is controversial as other studies propose an accretionary prism mechanism. A key difference between these models resides in the kinematics proposed for the Wenchuan -Maoxian (WM) fault zone, a major tectonic structure of the Longmen Shan. We constrain the Cenozoic kinematics of the WM fault zone by combining structural observations, fault gouge K/ Ar dating and 40Ar/39Ar dating of syn-kinematic white mica. Normal / right lateral ductile deformation occurred at 28.0 +/- 0.9 Ma while top-to-the-east reverse deformation at 15.4 +/- 0.2 Ma. K/Ar ages of authigenic illite from two fault gouges show that brittle right-lateral / reverse deformation was active at 6.9 +/- 2.9 Ma. These ages are consistent with the relative vertical motions across the fault zone deduced from thermochronology. Three deformation phases can be identified: right-lateral / normal in the Middle Oligocene (-30-25 Ma), reverse in the middle Miocene (25-15 Ma), and right-lateral / reverse since the upper Miocene (since-6 Ma). The WM fault zone never experienced pure normal motion, and only shortening since the Oligocene, in contrast to predictions of lower crustal channel-flow extrusion models. These results are in favor of a crustal accretionary prism model for the Cenozoic building of the eastern Tibetan plateau.

During the Cenozoic, the Menderes Massif (western Turkey) records several tectonic and thermal events from subduction to collision, then back-arc extension. But the detailed timing of the succession of different P-T regimes and deformation until today remains debated. To address this, we targeted the main shear zones, providing for the first time a full picture of the 40Ar/39Ar system across the massif. This approach is combined with Tmax, and P-T estimates tied to kinematic-structural data. Extensive sampling along the large top-S Selimiye shear zone allows constraining the deformation at least between 44 and 33 Ma. This shear zone acted as a thrust and was active under HT-MP (530 - 590 °C and 8.5 - 10 kbar). Conversely, the top-S South Menderes Detachment System is associated with a younging of 40Ar/39Ar ages related to exhumation and strain localization during the Late Oligo-Miocene in the Central Menderes Massif. The Bozdağ top-S shear zone then allowed the exhumation of the Bayındır nappe at ~ 21 Ma from high-temperature metamorphic conditions (590 °C). Based on these new elements, we propose for the first time a detailed scenario of the Menderes Massif evolution from the Late Cretaceous to the Present. We finally discuss why the Menderes Massif belongs currently to the regions with the highest geothermal potential in the world. We propose that geothermal activity here is not of magmatic origin but rather associated with active extensional tectonics (detachments) related to the Aegean slab dynamics (i.e., slab retreat and tearing).

Using target-matching techniques combining 40Ar/39Ar crystal-mapping with elemental mapping and high-resolution electron microscopy, this study investigates the 40Ar behavior in very-slowly cooled mus-covite from the Harney Peak Granite (HPG, South Dakota, USA). Detailed age mapping along (001) in sin-gle crystals from different localities of the HPG documents age gradients in excess of ti 300-400 m.y., with conspicuous internal 40Ar/39Ar zoning. This suggests (001) layer-parallel 40Ar transport driven by diffusion, consistent with previous 40Ar/39Ar crystal-mapping studies. The age distribution pattern is complex, however, and defines a mosaic of sub-grain domains with more retentive core zones, broadly ti 250-300 lm across, separated by zones of high diffusivity varying in shape and extent. The maximum ages preserved in the core domains are independent of their size but vary linearly with the bulk areal extent of the peripheral (or surrounding) high-diffusivity zones. Spatial 40Ar/39Ar relationships inside each grain point to a mechanism of multipath continuum-diffusion interaction between subdomains across the whole crystal, rather than via discrete non-interracting domains such as in K-feldspars. A close spatial correlation exists between younger ages, Na-depleted (K-enriched) zones, and density of microstructural defects. These defects, identified as lenticular voids and basal partings (< 100 nm-long), developed in response to inward K $ Na interdiffusion during late-magmatic stages, in the absence of deformation. Coupled variations in density of microstructural defects and Na-K interchange are inferred to control the bulk diffusion-domain structure of HPG muscovite. Quantitative diffusion modeling of cou-pled compositional-defect-isotopic variations indicates that 40Ar diffusivity may be enhanced by up to six orders of magnitude in defect-controlled high-diffusivity zones relative to less defective (pristine) domains. On the other hand, empirical diffusivity estimates required to preserve the core ages are com-mensurate with diffusion estimates independently derived from recent atomistic simulations. (c) 2022 Elsevier Ltd. All rights reserved.

Using target-matching techniques combining Ar40/Ar39 crystal-mapping with elemental mapping and high-resolution electron microscopy, this study investigates the Ar40 behavior in very-slowly cooled muscovite from the Harney Peak Granite (HPG, South Dakota, USA). Detailed age mapping along (001) in single crystals from different localities of the HPG documents age gradients in excess of ∼ 300–400 m.y., with conspicuous internal Ar40/Ar39 zoning. This suggests (001) layer-parallel Ar40 transport driven by diffusion, consistent with previous Ar40/Ar39 crystal-mapping studies. The age distribution pattern is complex, however, and defines a mosaic of sub-grain domains with more retentive core zones, broadly ∼ 250–300 μm across, separated by zones of high diffusivity varying in shape and extent. The maximum ages preserved in the core domains are independent of their size but vary linearly with the bulk areal extent of the peripheral (or surrounding) high-diffusivity zones. Spatial Ar40/Ar39 relationships inside each grain point to a mechanism of multipath continuum-diffusion interaction between subdomains across the whole crystal, rather than via discrete non-interracting domains such as in K-feldspars. A close spatial correlation exists between younger ages, Na-depleted (K-enriched) zones, and density of microstructural defects. These defects, identified as lenticular voids and basal partings (< 100 nm–long), developed in response to inward K ↔ Na interdiffusion during late-magmatic stages, in the absence of deformation. Coupled variations in density of microstructural defects and Na–K interchange are inferred to control the bulk diffusion-domain structure of HPG muscovite. Quantitative diffusion modeling of coupled compositional–defect–isotopic variations indicates that Ar40 diffusivity may be enhanced by up to six orders of magnitude in defect-controlled high-diffusivity zones relative to less defective (pristine) domains. On the other hand, empirical diffusivity estimates required to preserve the core ages are commensurate with diffusion estimates independently derived from recent atomistic simulations.

Mediterranean climates are characterized by warm, dry summers and mild, rainy winters. Previous studies suggest that over the last 1.36 Myr, Mediterranean winter rainfalls were in phase with the African monsoon. Here we present a high-resolution terrestrial and marine dataset for the Marine Isotope Stage 17 interglacial (Middle Pleistocene) from Southern Italy, showing that precipitation rates and regimes in the central Mediterranean varied independently of the monsoon system. Specifically, events of extreme summer precipitation were promoted by increased regional insolation rates and/or extratropical cyclones, and their magnitude was further enhanced by the advection of cool and humid North Atlantic air during stadials. Our findings provide new information on the short- to mid-term natural hydroclimatic variability of the Mediterranean basin, and offer new critical insights on land–ocean interactions at the regional scale by complementing previous analyses on the displacement of storm tracks toward southern Europe.

Using target-matching techniques combining Ar40/Ar39 crystal-mapping with elemental mapping and high-resolution electron microscopy, this study investigates the Ar40 behavior in very-slowly cooled muscovite from the Harney Peak Granite (HPG, South Dakota, USA). Detailed age mapping along (001) in single crystals from different localities of the HPG documents age gradients in excess of ∼ 300–400 m.y., with conspicuous internal Ar40/Ar39 zoning. This suggests (001) layer-parallel Ar40 transport driven by diffusion, consistent with previous Ar40/Ar39 crystal-mapping studies. The age distribution pattern is complex, however, and defines a mosaic of sub-grain domains with more retentive core zones, broadly ∼ 250–300 μm across, separated by zones of high diffusivity varying in shape and extent. The maximum ages preserved in the core domains are independent of their size but vary linearly with the bulk areal extent of the peripheral (or surrounding) high-diffusivity zones. Spatial Ar40/Ar39 relationships inside each grain point to a mechanism of multipath continuum-diffusion interaction between subdomains across the whole crystal, rather than via discrete non-interracting domains such as in K-feldspars. A close spatial correlation exists between younger ages, Na-depleted (K-enriched) zones, and density of microstructural defects. These defects, identified as lenticular voids and basal partings (< 100 nm–long), developed in response to inward K ↔ Na interdiffusion during late-magmatic stages, in the absence of deformation. Coupled variations in density of microstructural defects and Na–K interchange are inferred to control the bulk diffusion-domain structure of HPG muscovite. Quantitative diffusion modeling of coupled compositional–defect–isotopic variations indicates that Ar40 diffusivity may be enhanced by up to six orders of magnitude in defect-controlled high-diffusivity zones relative to less defective (pristine) domains. On the other hand, empirical diffusivity estimates required to preserve the core ages are commensurate with diffusion estimates independently derived from recent atomistic simulations.

Muscovite ranks among the most commonly dated minerals in 40Ar/39Ar geochronology. Yet, its use in thermochronological reconstructions is hampered by the lack of reliable data on its 40Ar diffusional behavior. In this contribution, we investigate 40Ar lattice diffusion in muscovite at the atomic scale using Molecular Dynamics (MD) simulations combined with Nudged Elastic Band (NEB) and Transition State Theory (TST). Classical MD simulations of 40Ar recoil dynamics in 2M(1) muscovite reveal that 40Ar initially resides predominantly in the interlayer region, close to its production site. Systematic computations of migration barriers coupling NEB with TST identify the divacancy mechanism as the more energetically favorable pathway for 40Ar diffusion in the interlayer region, with characteristic activation energy E = 66 kcal.mol(-1) and frequency factor D-0 = 6 x 10(-4) cm(2).s(-1). For typical cooling rates between 1-100 degrees C.Ma(-1) and grain size varying from 0.1 and 1 mm, these parameters predict closure temperatures significantly higher (similar to 200 degrees C) than currently accepted maximum estimates (similar to 500 degrees C). Consistent with long-standing empirical evidence, our theoretical results downplay the role of purely thermally activated diffusion in promoting efficient 40Ar transport in ideal (stoichiometrically stable and undefective) muscovite. Along with experimental and field-based evidence, they call for more complex physics to explain the 40Ar retention properties of natural muscovite, most notably by considering crystal-chemical disequilibrium interactions and the reactivity of the interlayer with the external medium. (C) 2022 Elsevier Ltd. All rights reserved.

The emplacement of alkali-rich syenites was almost contemporaneous with the mantle source enrichment and closely followed by initial fast cooling dated by 40Ar/39Ar amphibole-biotite ages ranging between 329.8 +/- 1.6 and 331.4 +/- 0.7 Ma, corresponding to rapid exhumation of the Variscan orogenic mot in Central Europe. The U-Pb apatite age of 305.9 + 5.3 Ma likely reflects further cooling to lower temperatures. The syenite emplacement was linked to the early impulse of ultrapotassic magmatism associated with the Andean-type subduction of the Saxothuringian domain beneath the Moldanubian block. The close temporal association of K-rich magmatism in the Saxothuringian and Moldanubian Zone is indicated by identical cooling ages of miaskitic syenites and other Saxonian ultrapotassic rocks, as revealed by 40Ar/(39) Ar dates around 330 Ma. The emplacement of alkali-rich syenites was almost contemporaneous with the mantle source enrichment and closely followed by initial fast cooling dated by 40Ar/39Ar amphibole-biotite ages ranging between 329.8 +/- 1.6 and 331.4 +/- 0.7 Ma, corresponding to rapid exhumation of the Variscan orogenic mot in Central Europe. The U-Pb apatite age of 305.9 + 5.3 Ma likely reflects further cooling to lower temperatures. The syenite emplacement was linked to the early impulse of ultrapotassic magmatism associated with the Andean-type subduction of the Saxothuringian domain beneath the Moldanubian block. The close temporal association of K-rich magmatism in the Saxothuringian and Moldanubian Zone is indicated by identical cooling ages of miaskitic syenites and other Saxonian ultrapotassic rocks, as revealed by 40Ar/(39) Ar dates around 330 Ma.

Widespread overprinting of early high‐pressure/low‐temperature (H P /L T ) subduction stages due to subsequent collisional or late‐orogenic tectono‐metamorphic events is a common feature affecting the interpretation of geochronologic data from H P /L T orogens. The Betic‐Rif orogen is exemplary in this connection as a great majority of published radiometric ages are found to cluster around 20 Ma. This clustering is commonly interpreted as reflecting a short, yet complex, succession of tectono‐metamorphic events spanning only over a few Myr, including back‐arc extension and overthrusting of the Internal Zones on the External Zones. An alternative explanation consists in the poor preservation of a much earlier H P /L T metamorphic event, presumably Eocene, coeval with subduction and crustal thickening in the Internal Zones, and particularly the Alpujárride Complex. However, this age is vividly debated due to widespread resetting by the Early Miocene H T /L P overprint. In this study, we provide new 40 Ar/ 39 Ar evidence from white micas selected along an E‐W section of the Internal Betics, from the central to the eastern Alpujárride Complex. Our new data show (a) that exceptionally well‐preserved H P /L T parageneses in this unit retain a well‐defined Eocene age around 38 Ma, and (b) that widespread 20 Ma ages recorded all along the section correspond to a regional stage of exhumation, coeval with a major change in the kinematics of back‐arc extension. Our study provides conclusive evidence that 40 Ar/ 39 Ar dating of carefully targeted H P /L T associations can overcome the problem of extensive late‐orogenic overprinting, testifying for an Eocene H P event around 38 Ma in the Betic‐Rif orogen.

Pantelleria volcano has a particularly intriguing evolutionary history intimately related to the peralkaline composition of its explosively erupted magmas. Due to the stratigraphic complexity, studies over the last two decades have explored either only the pre-Green Tuff ignimbrite volcanism or the post-Green Tuff activity. We here focus on the whole evolutionary history, detailing the achievements since the first pioneering studies, in order to illustrate how the adoption and integration of progressively more accurate methods ($^{40}\mathrm{Ar}/^{39}\mathrm{Ar}$, paleomagnetism, petrography, and detailed field study) have provided many important independent answers to unresolved questions. We also discuss rheomorphism, a distinct feature at Pantelleria, at various scales and possible evidence for multiple, now hidden, caldera collapses. Although the evolutionary history of Pantelleria has shown that each ignimbrite event was followed by a period of less intense explosivity (as could be the present-day case), new geochronological and geochemical data may indicate a long-term waning of volcanic activity.