Reconstructing past lifeways and diets is essential to understanding the emergence of urban societies. However, in what are now arid environments like southern Mesopotamia, poor collagen preservation has long hampered direct isotopic analysis of trophic levels. This limitation has left key gaps in our understanding of subsistence in one of the world's earliest urban heartlands. Here, we apply zinc isotope analysis to human and faunal dental enamel from the third-millennium BCE site of Abu Tbeirah (Iraq), integrating δ13C, δ18O, and trace element ratios (Ba/Ca and Sr/Ca). This multiproxy approach reveals an omnivorous diet based on C3 cereals, terrestrial animal products (likely including pigs), and limited freshwater resources, with no or little evidence of marine fish consumption, despite the site's proximity to the ancient shoreline. Dietary patterns do not vary by sex, suggesting broad access to similar food sources within this nonelite population. Moreover, zinc and carbon isotopes proved valuable in identifying animal feeding practices. Our results provide direct dietary evidence from southern Mesopotamia, overcoming long-standing preservation challenges. The results allow us to evaluate specific expectations about diet and animal management in a collagen-poor context, also highlighting early-life feeding behaviors. They demonstrate the power of zinc isotopes to reconstruct trophic level in collagen-poor contexts, opening broad avenues for bioarchaeological research in early complex societies.
Amorphous calcium carbonate (ACC) is a common precursor of crystalline CaCO3 minerals whose chemical and isotopic composition are readily used as environmental archives. Yet the existing understanding on how chemical composition of ACC derived solids evolves during and after crystallization is rather limited. To address this question, in this study, impurity free ACC was introduced in a solution containing a high concentration of dissolved inorganic carbon (DIC), as well as B, Li, Na and Mg and let transform to crystalline CaCO3. The aqueous fluid was also enriched in 13C in order to assess the progress of the transformation reaction. Experiments were conducted at 5, 25 and 40 degrees C and the total reaction time was 90 days. The transformation of ACC mainly proceeds via its dissolution and re-precipitation and the mineralogy of the crystalline product varies at the different reaction temperatures. The observed mineral transformations are mainly affected by temperature, whereas the reaction progress is not the same in all reaction temperatures and a complete mixing of C pools between solid and reactive fluid is only observed in 25 degrees C runs. Moreover, the distribution coefficients of Li and Na between the solids and the fluid reduce significantly over time and at the end of the runs appear similar to those observed in seeded growth experiments conducted at low degrees of supersaturation with respect to CaCO3. These observations are discussed in combination with the implications they have for the interpretation of the chemical compositions of biogenic and abiotic samples that are derived from ACC and are routinely used as environmental proxies.
Ubinas is the most active volcano in Peru and has exhibited recurrent eruptive activity in recent decades, including eruptions in 2006–2009, 2013–2017, 2019, and 2023–2025. Here, we present a three-dimensional magnetotelluric (MT) study aimed at investigating the structure and dynamics of its magmatic–hydrothermal system. The MT model reveals an asymmetric, trans-crustal conductive architecture extending from the lower crust to the surface. At depths of 32–40 km below the surface, a deep conductive anomaly (1–5 Ω·m) is interpreted as a primitive basaltic–andesitic magma reservoir, consistent with independent petrological and seismic constraints. Above this reservoir, two overlying, nearly vertical conductors at approximately 14–25 km and 5–13 km depth (8–15 Ω·m) are interpreted as deep and intermediate-crustal magma reservoirs, respectively. The intermediate-crustal reservoir is consistent with a crystal-rich mush containing melt fractions generally below 30%, whereas the deeper basaltic–andesitic reservoir is consistent with higher melt fractions, locally exceeding 50%. At shallow levels, a conductor (<5 Ω·m) is interpreted as an active hydrothermal system, overlain by a clay-rich conductive cap that controls fluid circulation and discharge. The spatial distribution of seismicity supports pathways linking the deep magmatic reservoirs with the shallow hydrothermal system. The low-resistivity anomaly beneath the southeastern flank is consistent with intense fracturing and hydrothermal alteration, suggesting progressive mechanical weakening. These results support a vertically organized trans-crustal magmatic–hydrothermal system beneath Ubinas, providing an integrated framework for understanding magma transport, fluid circulation, and volcanic hazards in active Andean volcanic systems.
Diet is a key to evaluating social and health inequalities over time, as it reflects disparities in access to resources often linked to socioeconomic and gender factors. Stable carbon and nitrogen isotopes, while semi-quantitative, typically limit intersite comparisons, as the results are tied to local baseline isotope values. In this study, we overcome this limitation by applying the interdecile ratio-a metric from economics-to isotope data from 12,281 individuals across 393 European sites over millennia. Our isotope-based dietary inequality index reveals the nonlinear evolution of dietary disparities over time and across different geographical areas. Sex-based disparities are evident throughout all time periods. Male individuals are consistently overrepresented in the upper deciles, indicating greater access to animal proteins, while females dominate the lower deciles, reflecting more restricted access. Neolithic societies exhibit homogeneous diets at the population level, but animal protein consumption tends to differ between men and women. As expected, Bronze Age carbon interdecile indexes mark increasing dietary inequality, likely linked to agricultural advances and social hierarchies. Dietary disparities peak during Antiquity, although the gap between the sexes narrows slightly. This diachronic analysis highlights the complex interactions between diet, social structures, and gender and provides a robust framework for comparative studies of health inequalities in archaeology.
The Sioule region in the northern part of the French Massif Central of the Variscan belt hosts the Echassières complex, where a large W(-Sn) quartz vein system was intruded by the Beauvoir rare-metal granite (RMG) hosting disseminated Sn, Nb-Ta and Li mineralization. We combined whole-rock geochemical data, zircon U-Pb geochronology of migmatites and felsic igneous rocks of the Sioule area, along with U-Pb dating of cassiterite, wolframite, and apatite in the Echassières complex to reconstruct the regional magmatic and metallogenic evolution. Results reveal: (i) early W mineralization at 351 ± 9 Ma, coeval with peraluminous granite magmatism (Chantelle and St-Gervais massifs) and a N115-striking dextral shear zone; (ii) a second W mineralization phase at 329 ± 5 Ma, linked to rare-metal-rich rhyolitic dykes and the Colettes granite during NW-SE extension, synchronous with regional biotite microgranites (Pouzol-Servant Massif) and trachy-dacitic tuffs and lavas; and (iii) late-orogenic emplacement of the Beauvoir RMG with minor hydrothermal Sn and W at ca. 320-310 Ma, synchronous with biotite granites hosting quartz-tourmaline orbicules (Champs Massif) and pyroclastic flows. Our study reveals a 40 Myr-long metallogenic evolution with hydrothermal W mineralization preceding hydrothermal Sn and magmatic Li-Sn-Nb-Ta. Each mineralization period coincided with widespread crustal magmatism involving the anatexis of late-Ediacaran metasedimentary rocks and Cambrian-Ordovician metagranites, as shown by the dating of zircon in migmatites and inherited zircon in Variscan igneous rocks. However, rare-metal-enriched magmas remained spatially confined to the Echassières complex suggesting a structural corridor that repeatedly focused magmas and fluids from a localized fertile source.
