Samuele Agostini

This study presents a high-resolution, multiproxy (carbon and oxygen isotopes, trace elements, and strontium isotopes) speleothem record from the Kurdistan Region of Iraq extending from the end of the Last Glacial Maximum (LGM) to the Early Holocene (18.0 to 7.5 ka), encompassing the Epipaleolithic–Neolithic transition in the core area of the Fertile Crescent (FC). The record shows that changes in local rainfall amount were coincident with changes in Greenland temperatures, with increased precipitation and enhanced multidecadal hydroclimatic variability during the Bølling–Allerød chronozone, followed by a drier and dustier Younger Dryas. Comparison with regional paleoclimate data suggests similar precipitation patterns across the FC, but with greater hydroclimate variability during the BA and drier conditions during the YD in the eastern sector. Crucially, the record provides a detailed and well-dated paleoenvironmental template by which to contextualize specific cultural events at the subregional scale, as revealed by recent archaeological research on key sites sharing similar environmental settings, allowing to investigate the role of climatic and environmental changes in shaping different neolithization patterns across the FC.

Earth’s lithospheric mantle is dominated (usually >90% vol.%) by a nominally volatile-free mineral paragenesis with peridotitic composition. The remaining lithologies are typically hydrous and/or carbonate-bearing assemblages (the latter mostly stable at P >2 GPa), representing the products of mantle metasomatism with, or without, involvement of subduction. Despite their importance, the modal compositions of these metasomes are poorly constrained, probably containing hydrous phases (amphibole and/or phlogopite), coupled with accessory minerals, such as apatite, ilmenite, rutile and/or carbonates. These assemblages are usually considered to be the source of unusual magmas, in particular ultrapotassic compositions, especially kamafugites (K ₂ O-rich, commonly ultracalcic, basic/ultrabasic lithologies). To evaluate if partial melting of such metasomes could effectively produce kamafugites, we performed partial melting experiments at 2.7 and 5 GPa, and 1200°C to 1550°C on clinopyroxenites variably enriched in phlogopite, olivine and accessory phases (apatite, oxides, titanite), and on a clinopyroxene glimmerite (with apatite and magnetite). At low degrees of melting, the glasses show extremely high TiO ₂ (2 O ₅ (21.6 wt.%), as accessory minerals are the principal contributors in the melting reactions. Although there are no known natural counterparts for these low-degree melt compositions, they might play a key role in re-fertilisation events in the upper mantle. At increased degrees of partial melting (∼50 to ∼90%), the experimental melts approach the compositions of silica-poor, potassic/ultrapotassic and ultracalcic rocks. Indeed, experimental-produced glasses share several geochemical similarities with natural kamafugites, partially overlapping for most of the major oxides. Clinopyroxene- and phlogopite-rich lithologies, variably enriched in olivine and accessory phases (apatite, oxides, titanite) probably occur as veins pervading the lithospheric peridotitic matrix, and their partial melting, especially at high degrees, may be a plausible explanation for the genesis of SiO ₂ -poor, K ₂ O- and CaO-rich compositions.

Iron isotopes are increasingly applied in Earth science fields, including cosmochemistry, geochemistry and environmental sciences. Refining non‐traditional stable isotope systematics requires well‐characterised isotopic reference materials to ensure accuracy and precision. Consequently, the direct comparison of data obtained from different laboratories is a key prerequisite for establishing reliable isotopic systematics. Here, we describe a new Fe isotope measurement method using multi‐collector‐ICP‐MS. The Fe isotope ratios of widely used geological reference materials (JB‐2, BHVO‐2, BE‐N, AGV‐1 and RGM‐1) were measured and new Fe isotope values for IAEA‐B5 (basalt from Mount Etna, Italy) are recommended. Anion exchange chromatography was used to separate Fe from the rest of the matrix. Mass bias was corrected using a standard‐sample‐standard bracketing method combined with Ni‐doping. Iron isotope ratios of JB‐2, BHVO‐2, BE‐N, AGV‐1 and RGM‐1 show strong agreement with published values and fall within reported analytical uncertainties. Based on these results, we validate and propose δ ⁵⁶ Fe = 0.103 ± 0.064 (2 s ) and δ ⁵⁷ Fe = 0.141 ± 0.068 (2 s ) as recommended values for IAEA‐B5. We further advocate the IAEA‐B5 as a robust and complementary reference material for analytical validation and quality control in Fe isotope studies, providing both a supplement to and an alternative for established iron isotope reference materials.

The B isotope systematics (δ¹¹B) in amphibole offer insights into fluid‐ and melt‐dominated processes in the crust‐mantle system. We developed an analytical strategy for in situ B isotope determination in amphibole using LA‐ MC‐ICP‐MS on material with a B fraction of a few μg g⁻¹ using 10¹³ Ω resistors. Sources of error deriving from matrix effects were evaluated. Two Ca‐amphiboles, one from Pargas, Finland (PRG), and another from the Finero Complex (S. Alps, FIN), were characterised as potential reference materials. PRG has a B mass fraction of 6.75 ± 1.10 μg g⁻¹ and a δ¹¹B value of ‐16.58 ± 0.06‰, while FIN has 3.27 ± 0.68 μg g⁻¹ of B and a δ¹¹B value of ‐5.90 ± 0.09‰. A standard‐sample‐standard bracketing method, using USGS BHVO‐2G basaltic glass as the bracketing ‘standard’ (calibrator), provided accurate and reproducible in situ δ¹¹B measurements with 2s of ± 2.86‰ (n = 87) for PRG and ± 3.96‰ for FIN (n = 70). These Ca‐amphiboles are suitable reference materials to assess accuracy during in situ B isotope determination with LA‐MC‐ICP‐MS. The potential of in situ B isotope determination in Ca‐amphibole as a geochemical tool to investigate petrogenetic processes of a well‐characterised amphibole‐bearing gabbro from the Adamello batholith (C. Alps) has been tested successfully.

The Pleistocene (∼0.6 Ma) Cupaello monogenetic volcano, cropping out in central Italy, belongs to the Intra Apennine Province (IAP). It is represented by a single lava flow with kamafugitic composition, associated with a volumetrically limited pyroclastic deposit and a phosphate‐rich layer close to the small vent. This kamafugite is characterized by ultrapotassic (K₂O = 5.2–7.6 mass %; K₂O/Na₂O = 18.0–33.9), ultracalcic (CaO/Al₂O₃ = 2.2–2.4), ultrabasic (SiO₂ = 42.6–44.1 mass %), and SiO₂‐undersaturated (∼29% CIPW normative leucite) composition, with a peculiar paragenesis (kalsilite, melilite, phlogopite, clinopyroxene, calcite, olivine and glass, plus accessory phases). Trace elements (e.g., high LILE, high LILE/HFSE, negative anomalies for Nb, Ta, Ti and Eu, and Pb peaks in primitive mantle‐normalized diagrams) and isotopic constraints (e.g., strongly radiogenic ⁸⁷Sr/⁸⁶Sr, unradiogenic ¹⁴³Nd/¹⁴⁴Nd, high Δ7/4) point to subduction‐modified mantle sources. Cupaello products fall within the field of the IAP volcanic products, which define, as a whole, clear negative correlations of compatible and incompatible trace elements, as well as of all the other major oxides, with CaO. These trends are here interpreted as the effect of assimilation of crustal carbonates rather than the presence of a Ca‐carbonatitic component in the source, as instead commonly reported in literature. Despite this general trend, we emphasize that Cupaello rocks derive from partial melting of a subduction‐modified carbonated phlogopite‐peridotite source, followed by a prolonged fractional crystallization of olivine‐ and melilite‐rich kalsilitolite assemblages. A carbonatitic component is required to explain the absence of feldspars in the ultrabasic, ultracalcic and strongly SiO₂‐undersaturated magma, whose composition was possibly modified in minimal amounts by carbonate assimilation at shallow depths.

The ancient city of Elaiussa Sebaste, currently Ayaş, is located on the southeastern coast of Turkey. It was one of the main trading Mediterranean harbours from the Augustan period until the early Byzantine era. The Arab invasion in the 7th century ce marked its definitive abandonment. A significant historical topic concerns the palaeoenvironmental evolution of the northern and southern harbours of Elaiussa Sebaste, including their decline and burial. An interdisciplinary study analysed six cores drilled in the current plains corresponding to the former harbour basins. A geoelectrical study, integrated with borehole stratigraphy, reconstructed the geometry of the carbonate bedrock that forms the accumulation base of the marine sediments. Sediments deposited from the 8th century bce to the 6th century ce include the development phases of the ancient city from the 3rd century bce onwards. Sedimentology, micropalaeontology (foraminifers, ostracods), palaeobotany (pollen, non‐pollen palynomorphs, microcharcoals, plant macroremains) and Pb isotopes provided a model of the environmental evolution in both harbour basins. The main harbour expansion phase, marked by a change in Pb concentration, is hypothesized to have occurred between 140 and 220 ce, which is consistent with the historical sources indicating the development of the city during the mid‐Roman Imperial period.

The Pleiades Volcanic Field is made up of some 20 monogenetic, partly overlapping scoria and spatter cones, erupted in the last 900 ka, cropping out from the ice close to the head of the Mariner Glacier in northern Victoria Land, Antarctica. Erupted products vary from hawaiite to trachyte, defining a complete mild Na‐alkaline differentiation trend. Mafic samples are characterized by multi‐elemental patterns typical of OIB magmas, moderately low ⁸⁷Sr/⁸⁶Sr (0.7037) and high ¹⁴³Nd/¹⁴⁴Nd (0.51284), with a clear within‐plate affinity, indicating a subcontinental lithospheric source. With increasing SiO₂, ⁸⁷Sr/⁸⁶Sr ratios increase up to 0.7052 and ¹⁴³Nd/¹⁴⁴Nd decrease to 0.51277, supporting the hypothesis of open‐system evolution, with significant crustal assimilation during fractional crystallization. The erupted volume of most evolved products (∼7 km³), according to fractionation models, suggests that primitive magmas should have been more than 10 times larger, indicating the occurrence of a large magma plumbing system, unexpected for a volcanic field of monogenetic scoria cones. The occurrence of a complete fractionation trend with large magma chambers and large assimilation rate is unusual, if not unique, among the alkali basaltic volcanic fields and it is matched by a climax of activity during the last glacial maximum (30 ka), as indicated by new ⁴⁰Ar‐³⁹Ar ages (30 ± 3 ka and 25 ± 2 ka) for samples from the two most prominent edifices. Therefore, we hypothesize a role of a thick ice cap in suppressing eruptions and ultimately leading to prolonged magma residence time in the subsurface, favoring significant fractionation coupled with unusual high rates of crustal assimilation.

Thríhnúkagígur Volcano, Iceland, is a composite spatter cone and lava field characteristic of basaltic fissure eruptions. Lava drainback at the end of the eruption left ~60 m of evacuated conduit, and a 4 × 104 m3 cave formed by the erosion of unconsolidated tephra by the feeder dike. Field relationships within the shallow plumbing system provide three-dimensional insight into conduit formation in fissure systems. Petrographic estimates and the relative volumes of the cave and erupted lavas both indicate xenolithic tephra comprises 5–10 % of the erupted volume, which cannot be reproduced by geochemical mixing models. Although crustal xenolith entrainment is not geochemically significant, we posit that this process may be common in the Icelandic crust. The Thríhnúkagígur eruption illustrates how pervasive, poorly consolidated tephra or hyaloclastite can act as a mechanically weak pre-existing structure that provides a preferential pathway for magma ascent and may influence vent location.