Damavand stratovolcano is situated within the central Alborz Mountains in northern Iran. Numerous studies have delved into the geodynamics and the factors contributing to the formation of Damavand volcano in the Alborz Mountains. The volcano comprises multiple lava flows and pyroclastic deposits, predominantly consisting of trachyte and trachyandesite. The lava flows often contain enclaves with various lithological compositions like monzonite, monzodiorite and monzogabbro, and these provide valuable insights into the magmatic history and evolution of Damavand volcano. Isotopic data (143Nd/144Nd = 0.512559–0.512623; 87Sr/86Sr = 0.704745–0.704929; 176Hf/177Hf = 0.282722–0.282773) indicate changes in the magma source during volcanic activity, although isotopic compositions of both the enclaves and their host rocks have similar 143Nd/144Nd vs 87Sr/86Sr values, which lie close of the Bulk Silicate Earth values. Trace elements indicate that Damavand volcano is geochemically adakitic (mainly low-silica adakites). The εNd values vs 87Sr/86Sr isotope ratios for both the enclaves and the host rocks further support the interpretation that these rocks are primarily adakites derived from a thickened lower crust. The interpretation of the petrographic, elemental and isotopic data suggests that the enclaves at Damavand volcano did not originate from a single eruption or phase. Instead, these enclaves are fragments of ancient magma reservoirs that crystallized at depth and were later brought to the surface by subsequent eruptions. The εNd vs 87Sr/86Sr isotope ratios further indicate that, as the volcano evolved over time, magma migration occurred from deeper to shallower depths in the Earth’s crust. This trend reflects the changing dynamics of magma generation and movement within the volcanic system, shedding light on the complex evolution of Damavand volcano. By studying these processes, we can gain valuable insights into the magmatic history and behavior of the volcanic systems and their evolution.

The Kribi Alkaline Igneous Complex (south Cameroon), within the Yaoundé Domain of the Central African Fold Belt (CAFB), provides evidence of significant Pan-African magmatic and tectonothermal events. Zircon U-Pb ages (ca. 602-591 Ma) constrain crystallization of the nepheline syenites during the D2 Pan-African event. 40Ar/39Ar analyses of individual amphibole and biotite crystals from ten samples yield ages ranging from 556.9 ± 1.1 Ma to 456.3 ± 1.0 Ma (2σ). These results document an intense D3 tectono-metamorphic activity between 558.7 and 550.5 Ma, followed by intermittent reactivations until ~ 518 Ma, and a later D4 phase initiated around 496 Ma, peaking at ca. 482-476 Ma and persisting down to ca. 456 Ma. This chronology reflects a sustained post-collisional activity within the Pan-African orogenic system. Geochemically, the nepheline syenites and associated mafic rocks are silica-undersaturated, metaluminous, and display miaskitic mineralogy. Their isotopic (εNd(0.6 Ga) = –1.9 to –8.4) and trace-element signatures (e.g., Nb/La, La/Yb, Th/Ta, Nb/Yb, Th/Nb, Zr/Hf, Nb/Ta, Zr/Sm, Hf/Sm) indicate derivation from an enriched, metasomatized subcontinental lithospheric mantle (SCLM) infiltrated by carbonatitic melts. Subsequent fractional crystallization processes further evolved the magmas. Zircon trace-element chemistry supports this petrogenetic model. Elevated HFSE and LREE concentrations reflect both magmatic differentiation and late-stage hydrothermal enrichment. Estimated crystallization temperatures (≈ 611-1000 °C) and variable redox states fO2 (ΔFMQ = –1.85 to +3.74) point to high-temperature and volatile-rich magmatic conditions during emplacement. Overall, these results highlight that the alkaline magmatism developed along a craton margin during transition from contractional to transcurrent tectonics, followed by Neoproterozoic-Cambrian structural reactivation.

Blue ice areas have the potential to preserve old ice near the surface, offering valuable archives of past climate beyond the range of continuous deep ice cores. Notably, million-year-old ice has been recovered at shallow depths in the Allan Hills blue ice area, in the Transantarctic Mountains. However, similar sites in other regions of Antarctica remain unexplored. The FROID project aims to identify and sample such old ice near the Belgian Princess Elisabeth Station in Dronning Maud Land, East Antarctica. This report details the first of two field expeditions, conducted during the austral summer of 2024–2025, with the goal of identifying a suitable drilling site for a shallow ice core (up to 200 m) in the Nils Larsen blue ice area. During the field campaign, we collected datasets to assess ice age, thickness and flow velocity, to determine potential and suitability for coring very old ice: (1) 10 m ice cores for absolute dating ( 81 Kr and 40 Ar methods), gas measurement (amongst others, δO 2 /N 2 , total air content, CO 2 , CH 4 , N 2 O) and ice fabrics; (2) surface ice samples for water stable isotope analysis (δ 1 8O and δD) to infer paleo-temperatures and spatial patterns in isotopic variation; (3) ground-penetrating radar (GPR) surveys of bed topography and ice thickness; (4) ApRES radar profiles for vertical velocity, internal structure, and ice fabric; (5) GNSS measurements for local ablation and surface motion; and (6) Uncrewed Aerial Vehicle (UAV) tests for future meteorite recovery applications. This report outlines the field preparation, methodologies used, and challenges encountered. The results will guide site selection for the follow-up drilling campaign and can serve as a practical guide for future blue ice fieldwork.

Evaporites are frequently reported in carbonaceous chondrites from hot and cold deserts, yet their origin remains debated between formation on the parent body or by post-fall terrestrial alteration. Here, we present a systematic characterization of Ca sulfate and Ca carbonate assemblages in four CO carbonaceous chondrites from different dense collection areas of the Atacama Desert (Los Vientos 123, El Medano 464, Calama 031, Paposo 088). We combine backscattered electron imaging, EDS, X-ray compositional mapping, Raman spectroscopy, and modal point counting to assess the distribution, mineralogy, and formation context of evaporites. Evaporites occur mainly as pore-and vein-filling phases and as replacements of Fe sulfides. Los Vientos 123 and El Medano 464 contain high abundances of Ca sulfates (similar to 2.5 +/- 0.35 vol%), Calama 031 is dominated by Ca carbonate veins (1.4 +/- 0.26 vol%) with minor Ca sulfate, and Paposo 088 shows only low Ca sulfate contents (0.47 +/- 0.15 vol%). These phases are systematically associated with Fe oxyhydroxides, jarosite-like phases, and strongly altered sulfides. The sulfate-and carbonate-rich assemblages in CO chondrites correlate with local soil geochemistry and microclimates. Limestone bedrock and more rain-influenced inland set different evaporite assemblages compared to coastal areas characterized by marine aerosols and salt-rich soils. Raman spectra indicate that the dominant Ca sulfate polymorph is anhydrite, lacking OH-stretching bands, consistent with precipitation from low-water activity, chloride-nitrate-rich brines and limited subsequent hydration. Disordered carbonaceous matter locally sheltered within sulfate-rich areas suggests that secondary evaporites can trap and preserve organic material, even if non-biological. Our results thus support (i) a terrestrial origin for Ca sulfates and Ca carbonates in Atacama CO chondrites; (ii) the stability of anhydrite as an indicator of extremely low water activity; and (iii) process analogues for evaporite formation in Martian settings, where anhydrite regions may be key targets to reconstruct aqueous conditions and assess organic preservation on Mars.

Blue ice areas have the potential to preserve old ice near the surface, offering valuable archives of past climate beyond the range of continuous deep ice cores. Notably, million-year-old ice has been recovered at shallow depths in the Allan Hills blue ice area, in the Transantarctic Mountains. However, similar sites in other regions of Antarctica remain unexplored. The FROID project aims to identify and sample such old ice near the Belgian Princess Elisabeth Station in Dronning Maud Land, East Antarctica. This report details the first of two field expeditions, conducted during the austral summer of 2024–2025, with the goal of identifying a suitable drilling site for a shallow ice core (up to 200 m) in the Nils Larsen blue ice area. During the field campaign, we collected datasets to assess ice age, thickness and flow velocity, to determine potential and suitability for coring very old ice: (1) 10 m ice cores for absolute dating (81Kr and 40Ar methods), gas measurement (amongst others, δO 2/N 2, total air content, CO 2, CH 4, N 2O) and ice fabrics; (2) surface ice samples for water stable isotope analysis (δ 18O and δD) to infer paleo-temperatures and spatial patterns in isotopic variation; (3) ground-penetrating radar (GPR) surveys of bed topography and ice thickness; (4) ApRES radar profiles for vertical velocity, internal structure, and ice fabric; (5) GNSS measurements for local ablation and surface motion; and (6) Uncrewed Aerial Vehicle (UAV) tests for future meteorite recovery applications. This report outlines the field preparation, methodologies used, and challenges encountered. The results will guide site selection for the follow-up drilling campaign and can serve as a practical guide for future blue ice fieldwork.

One of the central goals of astrobiology is to test the hypothesis that extraterrestrial life exists. In practice, this means seeking imperfect proxies for life, or ‘biosignatures’. Experience shows that ambiguous and contestable results are common in this field. Many astrobiologists are highly attuned to the possibility of ‘false positive’ results that incorrectly indicate the discovery of life. But what if we fail to detect life that is (or was) actually present? Such ‘false negatives’ are bound to arise and they matter because they would represent failures to recognize past or present existence of life. Unlike false positives, false negatives are not currently high on research agendas, as they do not pose immediate risks. Here we identify multiple potential sources of false negatives in the search for life, including factors related to the abundance, activity, appearance and location of life; the preservation and detectability of its observable traces; and the limitations inherent in our detection methods. We call for the development of a deliberate research strategy that systematically addresses these risks. Identifying and constraining such sources is essential to reduce the likelihood of overlooking genuine evidence of life. It is important that astrobiology considers the case of not being able to recognize past or extant presence of life in observations—false negatives. This Perspective identifies sources of false negatives and suggests a framework focused on reducing their risk.

Rare earth element (REE) content and Sr and O isotope composition of bones and teeth are widely used as proxies for palaeoecology, palaeoenvironments and taphonomy. However, the interpretation of these data is often hindered by the complexity of diagenetic processes and history. In this paper, we use in-situ analyses (trace elements and Sr isotopes using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) and O isotopes using secondary ion mass spectrometry, SIMS) to investigate Lower Cretaceous (Late Barremian-Early Aptian) teeth and bones of Iguanodon bernissartensis to decipher the diagenetic processes, and to provide information about paleoenvironment and the non-migratory behaviour of iguanodons. Combined REE and isotope geochemistry highlights the importance of Fe-Mn oxyhydroxides in the uptake and release of REE by bones, and the change of diagenetic fluids over time. They also emphasize the role played by brines issued from the dissolution of deep-seated Visean evaporites, which brought considerable amount of S into the sinkhole lake where the iguanodons suddenly died in large numbers. Biological Sr and O isotope signatures obtained on the teeth suggest that Iguanodon bernissartensis was a non-migratory species, living and grazing in a restricted palaeogeographic area. O isotope data further indicates that the seasonality was marked, with cool/wet winters and warm to hot and dry summer.

Understanding the origin and preservation of early mantle heterogeneities is essential for reconstructing Earth's accretion and early differentiation history. This can be investigated using the short-lived 146Sm-142Nd and 182Hf-182W isotope systems, which provide insights into large-scale differentiation processes through 142Nd and 182W anomalies in Earth's oldest rocks. In this study, we present 182W data for Theo's Flow, a thick, differentiated, mafic-ultramafic flow of tholeiitic affinity, as well as 147Sm-143Nd, 176Lu-176Hf, and 187Re-187Os isotope data and trace element concentrations, including highly siderophile elements, for Theo's Flow and closely spatially and temporally associated Pyke Hill komatiites, both from the -2.7 Ga old Kidd-Munro Assemblage of the Abitibi greenstone belt, Ontario, Canada. Theo's Flow samples are characterized by an average & micro;182W value of +6.7 +/- 2.7, which, together with the previously reported positive & micro;142Nd anomaly of +6.8 +/- 2.5, indicate longterm survival of mantle domains resulting from magmatic differentiation early in Earth's history. If it is assumed that the bulk silicate Earth evolved with a suprachondritic Sm/Nd ratio, anomalies for both elements can be explained by a single silicate differentiation event at -4.54 Ga. Alternatively, if the bulk silicate Earth evolved with a chondritic Sm/Nd ratio, a model fractionation age of -4.45 Ga is obtained. In this case, due to extinction of 182Hf by that time, the 182W anomaly would have to have been generated by another process, such as derivation from a mantle source characterized by a deficit in late accreted materials. Regardless of the timing of the early silicate differentiation, the preservation of both 182W and 142Nd anomalies in the 2.7 Ga old rocks highlights the survival of early-formed mantle domains for nearly 1.8 Gyr after Earth's formation. Comparison of isotopic and chemical data for Theo's Flow with those for the Pyke Hill and Boston Creek komatiites, which were argued to have all been derived from melting in a single mantle plume, provides evidence for the survival of early mantle heterogeneities on a plume scale.

A total of 1222 Micrometeorites (MMs) from the late Devonian period were extracted from 26 kg of carbonates host rock fragments from the Chanxhe section in Belgium, from the Latest Famennian around 360 Myr, through magnetic separation and optical picking following dissolution with mild HCl, making it one of the largest fossil MMs collection, the largest from the late Devonian. The collection shows a wide diversity of texture, comparable to modern day collection but with different distribution. The majority of the MMs were I-type (90 %), with Gtype particles constituting 6 % and S-type particles at 1 %. Some of the S-types spherules are amongst the first silicate-type spherules, and amongst the most well-preserved in terms of texture and composition, to be described in fossil MMs collections. Additionally, intermediate type G/I representing <1 % of the sample are introduced for future fossil MMs classification. Distinguishing extraterrestrial (ET) MMs from terrestrial spherules is challenging due to weathering effects that modify both texture and composition during long residency time on Earth. The Na2O + K2O versus Fe/Si ratio plot is used for distinguishing ET from terrestrial spherules. Using textural and compositional data in combination creates a reliable ET spherule identification. I-type spherules show significant terrestrial alteration with notable loss of Ni and Cr, also observed in S-type spherules, with their silicate phases recrystallized in palagonite. G-type spherules display a mix of characteristics from I-type and S-type MMs. The study also highlights the presence of smaller spherules (<125 mu m) compared to modern micrometeorites (210-330 mu m), attributed to the predominance of I- and G-type spherules and long-term dissolution effects. Despite some alteration for some spherules, due diagenesis of the sedimentary host rocks, the collection shows extremely well-preserved spherules, with even some oxygen isotopes signature being preserved. Indeed, triple oxygen isotope analysis reveals that 5.8 % of the particles are related to ordinary chondrites (OC) and 33 % to carbonaceous chondrites (CCs), yielding a CC/OC ratio of approximately 5.6, with comparable distribution for all major types. Also, 9 % of I- and G/I-types are OC-related. Most I-type spherules likely originate from CM, CR, or H chondrites, with some possibly from iron meteorites. The findings suggest that the source materials of the ET flux have remained relatively consistent over the past 360 Myr, providing insights into historical Solar System events and Earth's environmental changes and extends the study of ET flux to Earth to CC compared to meteorites. In addition, combined with chemical and isotopic proxies and chrome spinel, the fossil MMs could assess the complete flux of cosmic dust to Earth. Finally, the use of fossil MMs could represent potential proxies for paleo-atmospheric oxygen levels and CO2 contents.

Characterization of micrometerorites from Roysane and Nils Larsen, Sør Rondane Mountains (East Antarctica)Zelinsky1, C., Krämer Ruggiu1, L., Boschi1, S., Binu Beena1, D., Debaille2, V., Schönbächler3, M., Valdes4,5, M., Heck4, P. R., Goderis1, S.1Archaeology, Environmental Changes, and Geo-Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels 2 Laboratoire G-Time, Université libre de Bruxelles, Avenue F.D. Roosevelt, 50 1050, Brussels 3 Institut für Geochemie und Petrologie, ETH Zürich, Clausiusstrasse 25, 8092 Zürich 4 Robert A. Pritzker Center for Meteoritics and Polar Studies, The Field Museum of Natural History, Chicago, IL 60605, United States 5 The School of the Art Institute of Chicago, Chicago, IL 60603, United States Each year ~5000 tons of extraterrestrial (ET) material accrete to Earth [1] with the majority consisting of small dust particles with size fractions of 2000 down to 10 µm, termed micrometeorites (MM). MMs are mainly thought to originate from evaporation tails of cometary bodies or to be produced during collision breakup events in the asteroid belt [2]. Despite their small size textural, chemical, and isotopic analysis of MMs has proven to be valuable in estimating Earth’s ET dust intake, reconstructing dust producing events in the Solar System, such as collision breakups of asteroids [3] and the convergence of new comets [4] and identifying potential parent body sources [5]. To provide a sturdy baseline for MM research and to mark MMs as a reliable tool in reconstructing the extraterrestrial influx over geological timescales, first, modern, well-preserved MMs need to be characterized in detail. Different sample locations in Antarctica have proven to be reliable sampling grounds as arid environments limit weathering effects and anthropogenic contamination is restricted [6]. Compared to melting snow and ice, sedimentary traps ensure an accumulation of sampling material over extended periods of time and relatively easy access. One issue in MM research is inconsistent sample extraction and preparation rendering a direct comparison between different MM collections challenging. This project aims at comparing MMs from a wide range of sample locations across Antarctica to provide a more robust baseline of modern MMs. This study mainly focusses on the not yet studied sample sites of Roysane and Nils Larsen, both small moraines situated in the south-west of the Sør Rondane Mountains in East Antarctica and compares these to other Antarctic collections both in the Sør Rondane Mountains and beyond. Thorough petrographic characterization is first applied to identify different MM types, reconstruct the overall material flux to Earth, account for possible weathering effects and preservation of individual MMs. Major- and trace-element analysis via EPMA and LA-ICP-MS is used to compare weathering effects and constrain peak temperatures during atmospheric entry heating [7]. Triple-oxygen analysis via SIMS (Secondary Ion Mass Spectrometry) aids in refining atmospheric entry processes possible parent body source materials as oxygen isotope compositions vary significantly between distinct chondrite subclasses [7] and can therefore link individual MMs to various parent bodies. Although this study focuses on sample locations Nils Larsen and Roysane, other Antarctic collections such as Widerøefjellet and Walnumfjellet are processed in parallel to account for differences in physiochemical properties and sedimentary host deposits between sample locations [8, 9]. Ultimately, this combined effort will aid in providing a reliable and consistent baseline for MM studies and in obtaining a better understanding of the overall ET flux to Earth, potential parent bodies and interaction dynamics between Earth and the Solar System. References:[1] Rojas et al., 2021, Earth Planet. Sci. Lett. 560, 116794.[2] Suttle and Folco, 2020, J. Geophys. Res. Planets 125, 1–18.[3] Farley et al., 2006, Nature, 439, 295–297.[4] Genge, 2017, Geophys.Res. Lett., 44, 1679–1686.[5] Suavet et al., 2010, Earth. Planet. Sci. Lett., 293, 313-320.[6] Suavet et al., 2009, Polar Sci. 3, 100–109.[7] Cordier et al., 2011, Geochim. Cosmochim. Acta 75 (2011) 5203–5218.[8] Goderis et al., 2020, Geochim. Cosmochim. Acta 270 (2020) 112–143.[9] Schmitz et al., 2019, Sci. Adv. 5, 1–11.

Abstract.The Isiro and Ngayu belts in northeastern Democratic Republic of Congo (DRC) are part of the Congo Craton and among the most poorly known Archean terrains worldwide. These belts consist of metavolcanic and metasedimentary rocks surrounded or intruded by granitoid rocks. minimum age of deposition for the supracrustal formations is defined at ca 2633 Ma (e.g. Allibone et al., 2020), whereas the granitoids were dated between 3200 Ma and 2530 Ma (Allibone et al., 2020; Turnbull et al., 2021) and are strongly deformed with variable proportions of mafic enclaves at outcrop scale (Turnbull et al., 2021). Both Isiros and Ngayu belts host important gold deposits, but the genetic relationships between gold mineralization, deformation and the diverse host rocks remain ambiguous. In this context, the work we present here is part of a multidisciplinary approach, combining the processing of satellite images and field observations using GIS to map the structural lineament that may control gold mineralization in the region. The results show that the strains are large, marked by NW-SE lineaments at low angle to the belt strikes and combined with a secondary ENE-WSW brittle structure. The overall structural pattern, together with the existence of artisanal gold mining in the area, emphasizes that gold mineralization is largely controlled by structures localization along the greenstone belts.Key words: Congo craton, gold mineralization, field observations, satellites images, structural lineaments. ReferenceAllibone, A., Vargas, C., Mwandale, E., Kwibisa, J., Jongens, R., Quick, S., Komarnisky, N., Fanning, M., Bird, P., MacKenzie, D., Turnbull, R., Holliday, J., 2020. Chapter 9: Orogenic Gold Deposits of the Kibali District, Neoarchean Moto Belt, Northeastern Democratic Republic of Congo, in: Sillitoe, R.H., Goldfarb, R.J., Robert, F., Simmons, S.F. (Eds.), Geology of the World’s Major Gold Deposits and Provinces. Society of Economic Geologists, p. 0. https://doi.org/10.5382/SP.23.09Turnbull, R.E., Allibone, A.H., Matheys, F., Fanning, C.M., Kasereka, E., Kabete, J., McNaughton, N.J., Mwandale, E., Holliday, J., 2021. Geology and geochronology of the Archean plutonic rocks in the northeast Democratic Republic of Congo. Precambrian Research 358, 106133. https://doi.org/10.1016/j.precamres.2021.106133

Rationale: Micrometeorites are extraterrestrial particles smaller than similar to 2 mm in diameter, most of which melted during atmospheric entry and crystallised or quenched to form 'cosmic spherules'. Their parentage among meteorite groups can be inferred from triple-oxygen isotope compositions, for example, by secondary ion mass spectrometry (SIMS). This method uses sample efficiently, preserving spherules for other investigations. While SIMS precisions are improving steadily, application requires assumptions about instrumental mass fractionation, which is controlled by sample chemistry and mineralogy (matrix effects). Methods: We have developed a generic SIMS method using sensitive high-mass resolution ion micro probe-stable isotope (SHRIMP-SI) that can be applied to finely crystalline igneous textures as in cosmic spherules. We correct for oxygen isotope matrix effects using the bulk chemistry of samples obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and model bulk chemical compositions as three-component mixtures of olivine, basaltic glass and Fe-oxide (magnetite), finding a unique matrix correction for each target. Results: Our first results for cosmic spherules from East Antarctica compare favourably with established micrometeorite groups defined by precise and accurate but consumptive bulk oxygen isotope methods. The Fe-oxide content of each spherule is the main control on magnitude of oxygen isotope ratio bias, with effects on delta O-18 up to similar to 6 parts per thousand. Our main peak in compositions closely coincides with so-called 'Group 1' objects identified by consumptive methods. Conclusions: The magnitude of SIMS matrix effects we find is similar to the previous intraspherule variations, which are now the limiting factor in understanding their compositions. The matrix effect for each spherule should be assessed quantitatively and individually, especially addressing Fe-oxide content. We expect micrometeorite triple-oxygen isotope compositions obtained by SIMS to converge on the main clusters (Groups 1 to 4) after correction firstly for magnetite content and secondarily for other phases (e.g., basaltic glass) in each target.

Astrobiology is a scientific field that is very interdisciplinary and developing very fast, with many new discoveries generating a high level of attention in both the scientific community and the public. A central goal of astrobiology is to discover life beyond Earth which is, with our current instrumentation and knowledge, arguably within our reach. However, knowledge exchange crossing disciplinary boundaries is becoming increasingly challenging due to different usage of nomenclature and scientific controversies often limited to subdisciplines. There have been some efforts to compile organized databases of terms, concepts and other relevant material within some of the subfields contributing to astrobiology, for example through manually curated online portals designed to benefit students, teachers and practitioners of astrobiology-related research. However, the developments within the subfields and the potentially premature communication of research findings are too fast for objective research portals to remain reliable and up-to-date enough to enable well-informed scientific discussions. We suggest here a novel strategy for developing an online tracers portal as a self-maintaining and self-updating information platform, that would allow not only for a relatively unbiased selection of research results, but also provide fast access to latest scientific discoveries together with potential controversies, such that users of the tracers portal can form their own opinion on all available data rather than obtaining an already filtered and potentially biased selection of information.

Antarctica is the most prolific place on Earth to find meteorites, which provide unique insights in the formation and evolution of our Solar System. Over 60% of all meteorite finds on Earth stem from so-called blue ice areas in the interior of the (East) Antarctic ice sheet. In these blue ice areas, a redirected ice flow and meteorological processes lead to the removal of surface layers. Meteorites once embedded in these layers of ice that are removed become exposed at the surface in high concentrations and are easy to spot in the field thanks to their contrasting dark color on blue ice. However, no meteorites have been found in areas where temperatures are relatively high. The absence of meteorites in these areas is explained by the fact that meteorites warm up under solar radiation, and as such these stones can melt the underlying ice, even when surface temperatures are well below zero. This very local melt causes the meteorite to move vertically downward into in the ice sheet, disappearing from the surface and hence impossible to see by eye and collect. Hence, in a warmer climate, meteorites are more prone to become unrecoverable. Using a data-driven approach, we estimated that with the currently increasing surface temperatures, meteorite loss rates exceed recovery rates multiple times. To estimate this loss rate, we first performed regional climate model simulations, for a low and a high emission scenario, in which blue ice areas are prescribed. Next, we fed this data to a machine learning algorithm that identifies meteorite-rich sites using over 12,000 known meteorite finding locations and their corresponding properties such as ice flow velocity and surface temperature. Until mid-century, projected losses are identical for the emission scenarios, after which losses are reduced for the low emission scenario and nearly constant for the high emission scenario. These meteorite losses demonstrate a (previously unnoticed) climate sensitivity of the interior of the Antarctic ice sheet. With temperatures remaining well below zero, even with several degrees of warming, meteorites are affected even by very minor (decimal) increases of surface temperatures during exceptionally warm events, which are expected to occur more frequently.

Ephesus was an important harbor city that flourished during the Roman period and ancient texts mention Almaden in Spain and the Cilbian fields of Ephesus as important cinnabar sources in antiquity. This work investigates whether imported cinnabar was used and whether this could be related to changes in painting activities over time. Microscopic analysis indicates a consistent preparation of cinnabar, hinting at a uniform source material quality or processing technique. However, the use of cinnabar varies among the architectural structures studied, indicating a plurality of painting techniques. A few of the analyzed cinnabar samples overlap with Turkish- and Balkan reference Pb isotope ratios; three samples from tabernas, however, deviate from this. The Hg isotope ratios reveal that cinnabar from carbonate-hosted deposits was likely used, and that processing of cinnabar included heating as suggested by ancient texts. Most notably, a correlation exists between the geochemical data and the painting technique - shifts in sourcing and cinnabar usage are potentially assignable to building chronology and/or usage. Through the lens of material provenance and processing, Ephesian cinnabar brings the organization of pigment trade into focus.

The Mars 2020 rover, Perseverance , encountered a range of basaltic igneous rocks on the floor of Jezero crater, two of which are olivine cumulates, formed by accumulation of olivine crystals from basaltic magma. These olivine cumulates lie in a geomorphically distinct region, named Séítah, on the Jezero crater floor. To understand the origin of the olivine cumulates and their relationship with the adjacent basalts of the Máaz formation, we calculated the composition of the parent magma of one of the olivine cumulates, named Brac, based on chemical analyses and mineralogic interpretations from the Planetary Instrument for X‐ray Lithochemistry (PIXL) instrument. Acceptable Brac/Dourbes parent magmas are olivine tholeiite basalts with SiO 2 ∼ 45%, MgO ∼ 8%, FeO Tot ∼ 27%, Al 2 O 3 ∼ 6%, and total alkali oxides of ∼2.8% weight. These compositions are similar to one of the Máaz basalts, the rock Rimplas, which is stratigraphically close to Séítah, but chemically distinct from other Máaz basalts. Rimplas could (within uncertainty) be a sample of the Brac parent magma, but it is more likely that Rimplas and Brac had a common (or similar) parent magma. Geochemical similarities between Rimplas and the other Máaz basalts thus suggest that Brac (and other olivine‐rich rocks of Séítah) and the Máaz basalts could be geochemically related; they could have been cogenetic and possibly contemporaneous, or could have been derived (at different times) from similar or related mantle source(s).