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This study presents a methodological advancement in the field of clumped‐isotope (∆47) thermometry, specifically tailored for application to freshwater ostracods. The novel ostracod clumped isotope approach enables quantitative temperature and hydrological reconstruction in lacustrine records. The relationship between ∆47 and the temperature at which ostracod shell mineralized is determined by measuring ∆47 on different species grown under controlled temperatures, ranging from 4 ± 0.8 to 23 ± 0.5ºC. The excellent agreement between the presented ∆47 ostracod data and the monitored temperatures confirms that ∆47 can be applied to ostracod shells and that a vital effect is absent outside the uncertainty of measurements. Results are consistent with the carbonate clumped‐isotope unified calibration (Anderson et al., 2021, https://doi.org/10.1029/2020gl092069), therefore, an ostracod‐specific calibration is not needed. The ostracod clumped‐isotope thermometer represents a powerful tool for terrestrial paleoclimate studies all around the world, as lakes and ostracods are found in all climatic belts. Plain Language Summary In the framework of global warming, the reconstruction of past climatic conditions is important to understand the future evolution of climate and its impact. Lake sediments can be used as archives to quantify these effects. This study presents a novel paleo‐thermometer based on the application of clumped‐isotope technique (i.e., measurement of the number of 13C–18O bonds in carbonate minerals that depends on the temperature of carbonate precipitation) on carbonatic microcrustacea, named ostracods that commonly live in lakes. By using ostracods that formed their shells at known temperatures, we demonstrate that they can be easily used to reconstruct water temperature and hydrological conditions (precipitation/evaporation). The ostracod clumped‐isotope thermometer represents a powerful tool for terrestrial paleoclimate studies around the world, as lakes and ostracods are located in all climatic belts. Key Points ∆47—ostracod signal accurately records the shell calcification temperature ∆47—ostracod signal is not affected by the so called “vital effect” The unified calibration of Anderson et al. (2021) can be used to convert the ∆47—ostracod signal into accurate temperatures

The Chicxulub asteroid impact event at the Cretaceous-Paleogene (K-Pg) boundary ~66 Myr ago is widely considered responsible for the mass extinction event leading to the demise of the non-avian dinosaurs. Short-term cooling due to massive release of climate-active agents is hypothesized to have been crucial, with S-bearing gases originating from the target rock vaporization considered an important driving force. Yet, the magnitude of the S release remains poorly constrained. Here we empirically estimate the amount of impact-released S relying on the concentration of S and its isotopic composition within the impact structure and a set of terrestrial K-Pg boundary ejecta sites. The average value of 67 ± 39 Gt obtained is ~5-fold lower than previous numerical estimates. The lower mass of S-released may indicate a less prominent role for S emission leading to a milder impact winter with key implications for species survival during the first years following the impact. The amount of S released by the Chicxulub impact event is empirically determined to be 5 times lower than previously estimated, with important consequences for our understanding of the climate cooling that ultimately led to the K-Pg mass extinction.

The high temperatures reached during cremation lead to the destruction of organic matter preventing the use of traditional isotopic methods for dietary reconstructions. Still, strontium isotope ( 87 Sr/ 86 Sr) and concentration ([Sr]) analyses of cremated human remains offer a novel way to assess changing consumption patterns in past populations that practiced cremation, as evidenced by a large amount of new data obtained from Metal Ages and Gallo-Roman human remains from Destelbergen, Belgium. The Gallo-Roman results show significantly higher [Sr] and a narrower interquartile range in 87 Sr/ 86 Sr (0.7093–0.7095), close to the value of modern-day seawater (0.7092). This contrasts with the Metal Ages results, which display lower concentrations and a wider range in 87 Sr/ 86 Sr (0.7094–0.7098). This typical Sr signature is also reflected in other sites and is most likely related to an introduction of marine Sr in the form of salt as a food preservative (e.g. salt-rich preserved meat, fish and fish sauce). Paradoxically, this study highlights caution is needed when using 87 Sr/ 86 Sr for palaeomobility studies in populations with high salt consumption.

Megalithism has been repetitively tied to specialised herding economies in Iberia, particularly in the mountainous areas of the Basque Country. Legaire Sur, in the uplands of Álava region, is a recently excavated passage tomb (megalithic monument) that held a minimum number of 25 individuals. This study analysed the carbon, nitrogen, oxygen, and strontium isotope ratios of 18 individuals, in a multi-tissue sampling study (successional tooth enamel sampling, incremental dentine sampling, and bulk bone collagen sampling). The results provide a high-resolution reconstruction of individual mobility, weaning, and dietary lifeways of those inhumed at the site. Oxygen and strontium isotope analysis suggest all individuals come from a similar, likely local, geological region, aside from one biological female who presents a notably different geographical birthplace, weaning, and dietary life history than the rest of the burial population. Comparisons to other nearby megalithic sites (∼35km as the crow flies), located in a valley area, reveal that, whilst sharing the same mortuary practices, these individuals held notably different lifeways. They highlight notably earlier ages of cessation of nursing (≤2 years at Legaire Sur vs. ≥4 years in other megalithic tombs), and a greater dependence on pastoralism than previously observed in lowland megalithic graves. The results from Legaire Sur reveal the complexity of the Late Neolithic-Chalcolithic transition in north-central Iberia, categorising yet another separate socio-economic group with distinctive lifeways inhabiting the region.

The Cretaceous/Paleogene boundary asteroid impact is recorded globally as a negative 187 Os/ 188 Os excursion, including in sediments recovered from the IODP-ICDP drilling within the peak ring of the Chicxulub structure in the Gulf of Mexico. The reconstructed marine 187 Os/ 188 Os curves can be used for global age correlations on the ~10 kyr scale. However, the versatility of Os isotope clock between the proximal and distal sites remains unclear. This paper presents 187 Os/ 188 Os records from early Paleocene sediments deposited in the Chicxulub impact basin and Mexican sites with biochronological scales. The results for these proximal sites show a recovery timescale of ~700 kyr, which is significantly longer than that of the distal sites (~200 kyr). The interval showing the 187 Os/ 188 Os decline coincides with the enrichment of hydrothermally-derived Mn, implying that hydrothermal venting at the Chicxulub structure may have played a role in the marine chemistry and ecosystem of the Gulf of Mexico. Sedimentary osmium isotopes from the Gulf of Mexico indicate that after the Cretaceous-Paleogene impact, nutrients were supplied by hydrothermal activity for 700 kyr and may have contributed to the post-extinction recovery of the marine ecosystem

Little is known of the properties of the sarsen stones (or silcretes) that comprise the main architecture of Stonehenge. The only studies of rock struck from the monument date from the 19 th century, while 20 th century investigations have focussed on excavated debris without demonstrating a link to specific megaliths. Here, we present the first comprehensive analysis of sarsen samples taken directly from a Stonehenge megalith (Stone 58, in the centrally placed trilithon horseshoe). We apply state-of-the-art petrographic, mineralogical and geochemical techniques to two cores drilled from the stone during conservation work in 1958. Petrographic analyses demonstrate that Stone 58 is a highly indurated, grain-supported, structureless and texturally mature groundwater silcrete, comprising fine-to-medium grained quartz sand cemented by optically-continuous syntaxial quartz overgrowths. In addition to detrital quartz, trace quantities of silica-rich rock fragments, Fe-oxides/hydroxides and other minerals are present. Cathodoluminescence analyses show that the quartz cement developed as an initial <10 μm thick zone of non-luminescing quartz followed by ~16 separate quartz cement growth zones. Late-stage Fe-oxides/hydroxides and Ti-oxides line and/or infill some pores. Automated mineralogical analyses indicate that the sarsen preserves 7.2 to 9.2 area % porosity as a moderately-connected intergranular network. Geochemical data show that the sarsen is chemically pure, comprising 99.7 wt. % SiO 2 . The major and trace element chemistry is highly consistent within the stone, with the only magnitude variations being observed in Fe content. Non-quartz accessory minerals within the silcrete host sediments impart a trace element signature distinct from standard sedimentary and other crustal materials. 143 Nd/ 144 Nd isotope analyses suggest that these host sediments were likely derived from eroded Mesozoic rocks, and that these Mesozoic rocks incorporated much older Mesoproterozoic material. The chemistry of Stone 58 has been identified recently as representative of 50 of the 52 remaining sarsens at Stonehenge. These results are therefore representative of the main stone type used to build what is arguably the most important Late Neolithic monument in Europe.

To fully assess the resilience and recovery of life in response to the Cretaceous–Paleogene (K-Pg) boundary mass extinction ~ 66 million years ago, it is paramount to understand biodiversity prior to the Chicxulub impact event. The peak ring of the Chicxulub impact structure offshore the Yucatán Peninsula (México) was recently drilled and extracted a ~ 100 m thick impact-generated, melt-bearing, polymict breccia (crater suevite), which preserved carbonate clasts with common biogenic structures. We pieced this information to reproduce for the first time the macrobenthic tracemaker community and marine paleoenvironment prior to a large impact event at the crater area by combining paleoichnology with micropaleontology. A variable macrobenthic tracemaker community was present prior to the impact (Cenomanian–Maastrichtian), which included soft bodied organisms such as annelids, crustaceans and bivalves, mainly colonizing softgrounds in marine oxygenated, nutrient rich, conditions. Trace fossil assemblage from these upper Cretaceous core lithologies, with dominant Planolites and frequent Chondrites , corresponds well with that in the overlying post-impact Paleogene sediments. This reveals that the K-Pg impact event had no significant effects (i.e., extinction) on the composition of the macroinvertebrate tracemaker community in the Chicxulub region.

This paper reviews habitability conditions for a terrestrial planet from the point of view of geosciences. It addresses how interactions between the interior of a planet or a moon and its atmosphere and surface (including hydrosphere and biosphere) can affect habitability of the celestial body. It does not consider in detail the role of the central star but focusses more on surface conditions capable of sustaining life. We deal with fundamental issues of planetary habitability, i.e. the environmental conditions capable of sustaining life, and the above-mentioned interactions can affect the habitability of the celestial body. We address some hotly debated questions including: How do core and mantle affect the evolution and habitability of planets? What are the consequences of mantle overturn on the evolution of the interior and atmosphere? What is the role of the global carbon and water cycles? What influence do comet and asteroid impacts exert on the evolution of the planet? How does life interact with the evolution of the Earth’s geosphere and atmosphere? How can knowledge of the solar system geophysics and habitability be applied to exoplanets? In addition, we address the identification of preserved life tracers in the context of the interaction of life with planetary evolution.

High concentrations of iridium have been reported in terrestrial sediments dated at 12.9 ka and are interpreted to support an extraterrestrial impact event as the cause of the observed extinction in the Rancholabrean fauna, changes in the Paleoindian cultures, and the onset of the Younger Dryas cooling [Firestone RB, et al. (2007) Proc Natl Acad Sci USA 104:16016-16021]. Here, we report platinum group element (PGE: Os, Ir, Ru, Rh, Pt, Pd), gold (Au) concentrations, and ¹⁸⁷Os/¹⁸⁸Os ratios in time-equivalent terrestrial, lacustrine, and marine sections to seek robust evidence of an extraterrestrial contribution. First, our results do not reproduce the previously reported elevated Ir concentrations. Second, ¹⁸⁷Os/¹⁸⁸Os isotopic ratios in the sediment layers investigated are similar to average crustal values, indicating the absence of a significant meteoritic Os contribution to these sediments. Third, no PGE anomalies distinct from crustal signatures are present in the marine record in either the Gulf of California (DSDP 480, Guaymas Basin) or the Cariaco Basin (ODP 1002C). Our data show no evidence of an extraterrestrial (ET)-PGE enrichment anomaly in any of the investigated depositional settings investigated across North America and in one section in Belgium. The lack of a clear ET-PGE signature in this sample suite is inconsistent with the impact of a large chondritic projectile at the Bølling-Allerød/Younger Dryas transition.