International Journal of Earth Sciences最新文献

{"title":"Cambro-Ordovician stratigraphic record of two distinctive Famatinian belts fringing SW Gondwana: insights from SHRIMP U–Pb zircon ages and geochemistry from the Sierra de Famatina (NW Argentina)","authors":"Carlos D. Ramacciotti, César Casquet, Matías M. Morales Cámera, Juan A. Murra, Mariano A. Larrovere, Juan A. Dahlquist, Sebastián O. Verdecchia, Pablo H. Alasino, Carlos I. Lembo Wuest, Edgardo G. Baldo","doi":"10.1007/s00531-024-02439-1","DOIUrl":"https://doi.org/10.1007/s00531-024-02439-1","url":null,"abstract":"<p>The Sierra de Famatina of northwestern Argentina contains one of the best Cambro-Ordovician stratigraphic records of the SW Gondwana margin. Two lithotectonic belts (Calalaste–Narváez and Famatina–Valle Fértil), separated by master faults, preserve evidence of two former volcano-sedimentary basins (Eastern and Western, respectively). The Calalaste–Narváez Lithotectonic Belt consists of an Ediacaran to early Cambrian basement unconformably overlain by a 490–480 Ma cover of very low-grade volcano-sedimentary and volcanic succession that presumably formed in an extensional tectonic regime. In contrast, the Famatina–Valle Fértil Lithotectonic Belt comprises a basement consisting of the late-lower-to-middle Cambrian metasedimentary Achavil and Negro Peinado formations unconformably overlain by meta/sedimentary and metavolcanic rocks ranging in age from the late Cambrian to the Middle Ordovician (ca. 490–460 Ma). This belt includes the Famatinian Cordilleran-type magmatic arc active mainly at ca. 473–468 Ma, coeval with andesite to rhyolitic volcanism (Suri and Las Planchadas formations). Rhyolitic tuffs of ca. 473 Ma (εNdi = − 4.1) were found in the La Aguadita Formation, allowing this unit to be re-assigned to the late Floian. The oldest magmatism of the Sierra de Famatina is characterized by isotopically evolved (εNdi = − 5.1) rhyolitic tuffs of ca. 490 Ma in the Bordo Atravesado Formation, which was coeval with deposition of Mn-enriched hydrothermal cherts. This early Famatinan volcanism contrast with that of similar age and isotopically less evolved occurred in the Calalaste–Narváez Lithotectonic Belt suggesting variations of the source of magmas across the space and time within the Famatinan Orogenic Cycle. We propose that both described lithotectonic belts likely diverge northwards into Chile and Peru, wrapping around the Arequipa–Antofalla Proterozoic block.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>\u0000","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"103 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141548712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mudrock overpressure, fracturing, and mud volcanism in the Lower Kura Depression, Azerbaijan","authors":"Sedat İnan, Muhammed Namazlı, Roksana Askerova, Ibrahim S. Guliyev","doi":"10.1007/s00531-024-02442-6","DOIUrl":"https://doi.org/10.1007/s00531-024-02442-6","url":null,"abstract":"<p>The Lower Kura Depression (LKD) in Azerbaijan is a unique place on Earth where enormous oil and oil–gas-condensate deposits coexist with mud volcanoes. Large mud volcanoes developed in this area as a result of favorable tectonic processes, depositional settings, and subsurface pressure conditions. Disequilibrium compaction leading to overpressurization of mudrocks, as well as gas generation, have been previously proposed as the main factors that cause overpressure and trigger mud volcanism. To assess the mechanisms contributing to mudrock overpressure, we conducted a 2D basin modeling work to simulate the burial, temperature, maturation, and pressure histories of the sedimentary pile along a 120-km-long geological cross-section in the ENE‒WSW direction perpendicular to major structures in the LKD. The results of the calibrated model suggest that the main petroleum source rocks of the LKD, namely the Oligocene–Middle Miocene Maykop and the Eocene Middle Koun mudrock formations, are still in the oil generation zone. Therefore, previously speculated gas generation effect on overpressurization is insignificant in the LKD. Modeling also predicts overpressure of varying magnitude in the potential hydrocarbon source rocks of dominantly mudstone lithology. We have verified that disequilibrium compaction caused by rapid sedimentation in the last 3 million years has led to mudrock overpressurization that exceeded rock strength. We take model-predicted fracturing as a proxy indicator of mud ascent and suggest that fracturing of the mudrocks enabled ascend of the mud via fault-associated weakness zones.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>\u0000","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"82 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polymetamorphic P–T evolution of the andalusite–garnet–staurolite–sillimanite-bearing schist from the Cushamen Complex (Argentina)","authors":"Samanta Serra-Varela, Sebastián O. Verdecchia, Carlos I. Lembo Wuest, Manuela E. Benítez, Juan A. Murra, Edgardo Baldo","doi":"10.1007/s00531-024-02437-3","DOIUrl":"https://doi.org/10.1007/s00531-024-02437-3","url":null,"abstract":"<p>A sample of micaceous schist of the Cushamen Metamorphic Complex in the Cushamen area (northwestern North Patagonia, Argentina) preserves a complex mineral assemblage, including staurolite, andalusite, garnet, sillimanite, biotite, quartz, and plagioclase. This unit proves an opportunity to analyse a complex mineral association often related to disequilibrium stages or polymetamorphic contexts. Through detailed petrological analysis combining mineral chemistry, X-ray compositional maps, conventional thermobarometry, and phase equilibria analysis, we reconstructed the pressure–temperature (<i>P–T</i>) path of this schist. The schist unit preserves a polymetamorphic history characterized by M₁, M₂, and M₃ events. The M₁ event is represented by biotite, muscovite, quartz, and plagioclase. The M₂ event, associated with local mid-Carboniferous pluton intrusion, is characterized by andalusite and garnet assemblages, with peak conditions at ~ 3.3 kbar and ~ 563 °C. The main M₃ event, at the time of the Carboniferous–Permian boundary, is defined by garnet, staurolite, sillimanite, biotite, muscovite, plagioclase, and quartz. This event records a progressive <i>P–T</i> evolution from ~ 3.5 kbar and ~ 553 °C to ~ 4.9–5.6 kbar and ~ 620–635 °C, nearing peak conditions. This work highlights the importance of comprehensive approaches in <i>P–T</i> trajectory reconstructions and the critical role of selecting the reactive bulk composition, particularly in rocks with complex mineral assemblages. In addition, this study significantly contributes to understanding the metamorphic evolution of the Cushamen Complex, a unit for which there is limited knowledge regarding its structural and metamorphic evolution. This complex is part of the igneous-metamorphic basement of North Patagonia region (Argentina), which records the Paleozoic evolution of the southwestern margin of Gondwana.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>\u0000","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"1 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Latest Pliensbachian to Early Toarcian depositional environment and organo-facies evolution in the North-German Basin (Hondelage Section)","authors":"Tim Marten, Wolfgang Ruebsam, Jörg Mutterlose, Guido L. B. Wiesenberg, Lorenz Schwark","doi":"10.1007/s00531-024-02433-7","DOIUrl":"https://doi.org/10.1007/s00531-024-02433-7","url":null,"abstract":"<p>The Pliensbachian/Toarcian boundary interval represents a transition from a coldhouse into a hothouse climate state, involving the demise of a land-based cryosphere, initiating a third-order global sea-level rise. Within the intensely studied Northwest Tethyan shelf region, the South-German Basin has been investigated in more detail than the North-German Basin (NGB). We here provide a palaeoenvironmental reconstruction of the Pliensbachian/Toarcian transition from the Hondelage fossil excavation site located in the NGB employing organic, isotope, and major/trace element proxies. Here, the late Pliensbachian was characterized by cold climate, low sea level, and a slow hydrological cycle, causing minor terrigenous sediment and nutrient fluxes to the basin, instigating low marine productivity. Shallow, well-mixed shelf waters of normal salinity favored aerobic degradation of planktonic biomass, preventing sedimentary accumulation of organic matter. These conditions changed in the earliest Toarcian, where increased temperatures led to sea-level rise via meltdown of land-based ice and accelerated the hydrological cycle, causing salinity stratification. Enhanced riverine sediment and nutrient supply from nearby landmasses promoted marine primary productivity, which caused anoxic conditions in bottom and pore waters favoring enhanced preservation and accumulation of organic matter. A short-lived sea-level fall at the Lower Elegans Bed coincided with lowered productivity and enhanced carbonate precipitation, due to reduced runoff and recovery of the carbonate factory. Increased redox-sensitive trace element concentrations above the Lower Elegans Bed suggest a renewed inflow of low-salinity arctic water masses via the Viking Corridor and potentially increased freshwater input, promoting water column stratification, enhanced planktonic productivity, and re-establishment of bottom water anoxia/euxinia.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>\u0000","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"201 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biochemically induced diagenesis of Jurassic micrite: evidence from phase analysis, carbon, oxygen, and strontium isotopes (Franconian Alb, Germany)","authors":"Wolfgang Blendinger","doi":"10.1007/s00531-024-02431-9","DOIUrl":"https://doi.org/10.1007/s00531-024-02431-9","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The marine Upper Jurassic rocks of the Franconian Alb consist largely of micritic carbonate of partly dolomitized reef mounds and bedded basinal limestone. All carbonates were lithified in the shallow (centimeters, meters) subsurface and have a wide range of ∂¹³C (≤ + 3‰ to − 10‰VPDB) but always negative ∂¹⁸O (− 1 to − 6‰VPDB). Dolomite and reef limestone show the highest ∂¹⁸O and ∂¹³C values. The most negative ∂¹³C (≥ − 10‰) occurs mainly as cement in dolomite of a basinal, partly dolomitic, biostrome interval. Basinal limestone shows intermediate ∂¹³C values. Because freshwater diagenesis and elevated temperatures cannot explain the observed isotope values, pH is here considered a major factor influencing the isotope signal of micritic limestone. The bulk sediment isotope signal was reset to lower values, from an original lime mud with ∂¹³C ≥ 3‰ and a ∂¹⁸O of ≥ + 1‰, as a result of biochemically induced diagenesis. Carbonate, probably mostly aragonite but occasionally including dolomite, was dissolved in a zone where low pH developed as a result of organic matter degradation. Dissolved carbonate was translocated by diffusion and re-precipitated as cement (ca. 50vol%) in a zone with elevated pH where all in situ lime mud ∂¹⁸O was reset. Imported cement carbonate precipitated in equilibrium with the pore fluid with negative isotope values, whereas ∂¹³C of the in situ lime mud remained unmodified. The negative shift of the bulk ∂¹³C and ∂¹⁸O is variable and depends on pH and the contribution of ¹²C from anaerobic sulfate reduction in the zone of cement precipitation. This produced an ubiquitous covariance of ∂¹⁸O and ∂¹³C. Incorporation of seawater-derived Mg²⁺ during recrystallization of carbonate can account for the local dolomitization. Elevated ⁸⁷Sr/⁸⁶Sr ratios are explained as a result of interaction of clay minerals with the stationary pore fluids. This study shows that the isotopic signal produced by biochemically induced shallow submarine subsurface carbonate diagenesis can be indistinguishable from freshwater diagenesis, that ∂¹⁸O and ∂¹³C of the bulk rock are always reset, and that carbonates can show, in the presence of clay minerals, elevated ⁸⁷Sr/⁸⁶Sr ratios even when the pore fluids were never exchanged.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"336 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoenvironment and vegetational history of a Middle Pennsylvanian intramontane peat swamp: an example from the Lower Radnice Coal, Kladno coalfield (Czech Republic)","authors":"Stanislav Opluštil, Cortland Eble, Zbyněk Šimůnek, Jana Drábková","doi":"10.1007/s00531-024-02438-2","DOIUrl":"https://doi.org/10.1007/s00531-024-02438-2","url":null,"abstract":"<p>The depositional environment, hydrology and vegetational history of the Lower Radnice Coal (Duckmantian) in the Kladno coalfield was studied using sedimentary geology, coal petrology and paleobotanical/palynological methods. The peat accumulating wetland of the coal formed in a fluvial paleovalley approximately 15 km long and 2–5 km wide, bordered by basement paleohighs and landlocked in the interior of the central European Variscides. The peat swamp evolved on top of mud-dominated floodplain successions pedogenically modified to a vertic gleyed Protosol. Probably climatically controlled rising ground water table resulted in paludification that from downstream part gradually spread upstream. Most clastic load was deposited in the upper part of the valley, whereas only mud suspension was dispersed downstream throughout the vegetated swamp. The best conditions for peat accumulation were situated in the eastern part of the paleovalley, where up to 1.5 m thick coal with thin bands of impure coal and carbonaceous mudstone formed in an occasionally inundated rheotrophic system with peat accretion controlled by regional ground water table. The peat swamp was vegetated mainly by lepidodendrid lycopsids with <i>Lepidodendron</i> and <i>Paralycopodites</i> being dominant genera. Shrubby to ground cover vegetation was represented by medulosallean pteridosperms, small shrubby lycopsids, sphenopsids, and herbaceous ferns. Tree ferns were locally abundant, especially in mineral-rich substrates. The rheotrophic character of the peat swamp may indicate higher seasonality of the Variscan interior, compared to coastal areas in the North Variscan foreland with contemporaneous ombrotrophic peats. Modern equivalents of the Lower Radnice Coal swamp are inland planar tropical peat swamps in tributary paleovalleys of the Tasek Bera in peninsular Malaysia and central Congo basins.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3><p>\u0000Lower Radnice Coal peat swamp.</p>","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"120 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141514162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Black shale deposition during the Paleocene–Eocene thermal maximum: shale-gas potential of the Patala Formation, Himalayan fold-and-thrust belt, Pakistan (eastern Tethys)","authors":"Nasar Khan, Ralf Littke, Gert Jan Weltje, Rudy Swennen","doi":"10.1007/s00531-024-02436-4","DOIUrl":"https://doi.org/10.1007/s00531-024-02436-4","url":null,"abstract":"<p>This study focuses on the implications of a global hyperthermal event, the Paleocene–Eocene Thermal Maximum (PETM) for the origin, preservation and maturation of organic matter (OM) in the Late Paleocene Patala Formation, Himalayan fold-and-thrust belt, Pakistan. The OM present in the full array of lithofacies of the Patala Formation is characterized by petrographic (vitrinite reflectance) and geochemical techniques (total organic carbon (TOC), total organic nitrogen (TON), Rock-Eval pyrolysis and stable C and N isotopes). These analyses record deposition of the formation in a Late Paleocene shallow marine shelf environment. The organic geochemical proxies indicate the presence of Type III mixed with subordinate Type II kerogen as well as thermally immature to early mature source rocks. OM is derived both from terrestrial and marine sources. Rather high TOC (&gt; 2 wt.%) and a negative carbon isotope excursion (CIE) reveal that the prevalence of anoxic conditions, at least for short periods, enhanced OM preservation. The quantity and quality of OM, as well as the thickness and thermal maturity of the Patala Formation, make it a potential target for shale-gas exploration. During PETM, the extensive biological activity and addition of organic carbon into shallow marine eastern Tethyan settings provided precursor materials for hydrocarbon source rocks and shale-gas generation within the Patala Formation. The high organic influx and suboxic to anoxic conditions during PETM also facilitated OM preservation within the formation. Thus, the transient global warming PETM event significantly contributed to the OM accumulation and its preservation, which implies the suitability of such source rocks for shale-gas exploration within the Potwar Basin (Pakistan) and similar basins in neighboring areas.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>\u0000","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"24 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Permian thermally-induced shear of the Cossato-Mergozzo-Brissago shear zone in the W-Southalpine basement, Italy: new petrological, geochemical and U–Pb geochronological constraints from the amphibolite-facies units of the Strona Ceneri Border Zone","authors":"F. Arboit, A. Decarlis, S. Ferrando, A. Maffeis, S. De Bernardi, A. Ceriani","doi":"10.1007/s00531-024-02435-5","DOIUrl":"https://doi.org/10.1007/s00531-024-02435-5","url":null,"abstract":"<p>The onset of the Cossato-Mergozzo-Brissago shear zone within the Strona Ceneri Border Zone in the W-Southalpine basement (Italy) and its role in the collapse of the Variscan crust have been the subject of considerable controversy. A set of new petrographic, geochemical and geochronological data from a suite of syn-kinematic migmatitic paragneiss and amphibolites in between the upper and lower crustal sections of the W-Southalpine basement provide new evidence on the thermo-mechanical role played by the middle crust in the evolution of the Permian Southalpine basement. The petrological investigation of these amphibolite-facies rocks and U–Pb ages from monazite crystals, occurring in distinct microstructural positions, provide new <i>P–T-t</i> constraints on the late-Paleozoic tectono-thermal evolution of the Variscan middle crust. The SCBZ units recorded tectonic events from a possible Early Silurian Cenerian (ca. 440 Ma) overprint onto the proto-sedimentary units of the Southalpine basement to the Mid-Permian (ca. 285 Ma) syn-kinematic partial melting event developed close to the CMB shear zone. Phase equilibria modeling is used to constrain the metamorphic conditions recorded by this section of the Variscan basement. Pressure–temperature (<i>P–T</i>) isochemical phase diagrams show that, after the ca. 330 Ma Variscan metamorphic peak at <i>P</i> ≅ 4 kbar and <i>T</i> &lt; 630 °C, the SCBZ paragneiss experienced isobaric heating up to 700–720 °C at ca. 285 Ma, which led to the formation of a syn-kinematic partial melting event coeval to the emplacement of the Mafic Complex in the lower Ivrea-Verbano Zone. These new geochronological and petrological constraints on the SCBZ paragneiss seem to corroborate the hypothesis that the transition from the stage of mature Variscan orogen to the stage of its collapse developed in the Permian, at ca. 285 Ma. Thus, we argue that the orogenic collapse was probably driven by the rheological weakening of the mid-crustal SCBZ units induced by their syn-tectonic partial melting and, ultimately, by the coeval thermal perturbation of the crust due to the intrusion of the mafic igneous suite at the crust-mantle boundary.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"31 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141514179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinematic reconstruction of the Alpine Tethys and surrounding Mesozoic rifted margins","authors":"Gianluca Frasca, Gianreto Manatschal, Pauline Chenin","doi":"10.1007/s00531-024-02407-9","DOIUrl":"https://doi.org/10.1007/s00531-024-02407-9","url":null,"abstract":"<p>In plate kinematic reconstructions, the restoration of rifted margins and their fossil equivalents exposed in orogens remains challenging. Tight fit reconstructions rely on the mapping of margins rift domains, their restoration to their pre-rift crustal thickness, and the removal of the oceanic and exhumed mantle domains. At present-day margins, high-resolution wide-angle seismic imaging allows mapping and measurement of rift domains; however, restoring fossil margins is trickier because they are largely overprinted and partially lost during convergence. Here, we present a new kinematic model for the Mesozoic rifting along the Tethys–Atlantic junction, which relies on two assumptions: (1) the width of the fossil Alpine Tethys rift domains was comparable to that of their present-day analogs, and (2) the necking zones of the former tectonic plates can be mapped, dated and used as kinematic markers. This reproducible workflow allows us, for the first time, to restore the rifted margins of the Alpine Tethys. Our reconstruction shows: (1) a westward propagation of extension through the Ionian, Alpine Tethys and Pyrenean rift systems from the Triassic to the Cretaceous, (2) the segmentation of the Mesozoic Tethyan rifted margins by strike-slip corridors, (3) the opening of an oceanic gateway at 165 Ma as mantle was exhumed along the entire Alpine Tethys and (4) the subdivision of the Mesozoic oceanic domain into compartments that were later consumed during subduction. This new model is supported by published data from the Alps, the Ionian Sea, the Pyrenees and the southern North Atlantic.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"5 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141514180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magma recharge in persistently active basaltic–andesite systems and its geohazards implications: the case of Villarrica volcano, Chile","authors":"J. A. Cortés, R. Gertisser, E. S. Calder","doi":"10.1007/s00531-024-02414-w","DOIUrl":"https://doi.org/10.1007/s00531-024-02414-w","url":null,"abstract":"<p>We report whole-rock chemistry, mineral chemistry, and volatile content from Villarrica volcano’s major recent paroxysms and background activity. Composition of the volcanic products are basalt to basaltic andesite with whole-rock SiO₂ content between 50 and 56 wt%, and a mineralogy dominated by olivine (Fo_71-80), clinopyroxene (Mg# ~ 50) and plagioclase (An_60–80). Volatile contents in melt inclusions are up to 1.5 wt% H₂O, 500 ppm CO₂, 1230 ppm sulfur and 580 ppm chlorine. Regardless of the type of activity, there are no substantial variations in whole-rock composition or the volatile content when the activity switches from background activity to a major paroxysm, strongly suggesting that this shift does not just depend on the arrival of new magma in the shallow magmatic system. Geothermobarometry constrains crystallization of the major mineral phases at various depths between 3 and 12.7 km, suggesting that degassing of a volatile-rich recharge magma occurs deeper than 12 km, producing efficient mixing throughout the whole system, and sustaining the lava lake activity in Villarrica’s summit crater. The occurrence of a permanent lava lake also suggests that the magma recharge must be close to continuous and therefore sudden changes between background and paroxysmal volcanic activity are likely controlled by relatively small changes in the rate of recharge and/or the volatile release rate in the magmatic system. This has important implications for the understanding of eruption triggers and the forecasting of volcanic eruptions.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>\u0000","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"12 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140931243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}