We present a sediment record from the Maitiku Springs alkaline spring-fed fen in western Latvia, documenting the history of fen development and CaCO3 precipitation. Our ultimate goal is to determine whether new data from this previously underexplored eastern Baltic region align with spatial and temporal patterns of tufa deposition in Central Europe. Our analysis integrates geochemical proxies, palaeobiological data and radiocarbon-dated terrestrial plant macrofossils recovered from two sediment cores extracted from the fen dome's top and slope. The Maitiku fen has been active since approximately 9.4 ka BP and shows two main phases of intensive CaCO3 precipitation: between 6.3 and 5.2 ka BP, and from around 3.6 ka BP to the present. These results support the view that, in the eastern Baltic, CaCO3 precipitation was largely limited during the Holocene Thermal Maximum (HTM), with current tufa formation initiating only in the late Holocene (after 5000 cal a BP). This pattern contrasts with that of the southern Baltic region, where the HTM coincided with the peak of tufa deposition, commonly followed by a decline in carbonate precipitation later in the Holocene. We attribute this regional difference primarily to contrasting hydroclimatic conditions during the HTM, linked to frequent anticyclonic circulation over northern Europe.

Abstract. In recent years, advances in machine learning have greatly improved the generation of maps showing the geographic distribution of isotope ratios (isoscapes), which have become essential tools for environmental, mobility and provenance studies in both modern and archaeological contexts. Among the various isotopic systems employed, strontium (Sr) is particularly useful because its 87Sr/86Sr ratio in the environment is largely controlled by the underlying geology through the composition of local soils and rocks. In this work, we present a new dataset of bioavailable 87Sr/86Sr ratios derived from n = 233 plant samples collected across southern Brazil, covering the states of Santa Catarina and Rio Grande do Sul (c.a. 370,000 km2). The measured ratios span from 0.70521 to 0.76039 and capture the bioavailable Sr isotope signatures over all major geological units in the region. We combined these new data with an extensive compilation of published bioavailable Sr measurements from across South America (including plants, fauna, ancient human remains, shells, snails, lichens, water and soils) to construct three random forest Sr isoscapes using different subsets of the combined dataset at the regional and continental scales. The first model incorporates the entire dataset ('All' dataset, n = 883 sites), the second is based on plant+fauna+lichen+human (n = 661 sites) and the third is limited to plant+lichen samples (n = 531 sites). Among the three models, the full dataset model shows lower predictive power, while the plant+fauna+lichen+human and the plant+lichen models yield better results, with similar RMSE (0.0049 and 0.0054) and R2 values (ca. 0.76). Compared to existing Sr isoscapes of South America, our models significantly enhance both spatial coverage and resolution of bioavailable Sr predictions, particularly in southern Brazil. The new bioavailable Sr isotope dataset from Santa Catarina and Rio Grande do Sul states is available at https://doi.org/10.5281/zenodo.17988601 (Scaggion et al., 2025a) and the compiled literature dataset is reported as supplementary material.

The Sierra Leone Ridge is the equatorial portion of the Mid-Atlantic Ridge (MAR) between the St. Paul (0-1 degrees N) and Doldrums (7-9 degrees N) Fracture Zones. At similar to 80 Ma, a submarine plateau -the Sierra Leone Rise which is now located off-ridge on the African plate and the Ceara Rise on the South American plate- formed due to excess magma production. Incompatible element-enriched MORB with high Sr-Pb but low Nd isotope ratios suggests that the high magma production could result from the interaction of a mantle plume with the Sierra Leone Ridge, the so-called Sierra Leone mantle plume that may now be centered at similar to 1.7 degrees N along the MAR. In order to define the nature of the mantle source beneath the Sierra Leone Ridge, we present major-trace element concentrations and radiogenic isotope ratios from abyssal peridotites and MORB from 4 to 7 degrees N along the MAR. High Hf isotope ratios are preserved in clinopyroxenes from abyssal peridotites (epsilon(Hf) = 12-54), indicating that the mantle beneath the Sierra Leone Ridge underwent extensive melting several 10(8)-10(9) years before remelting under the present MAR. Most peridotites have high epsilon(Hf), but low epsilon(Nd) similar to MORBs, although some extend to unusually low epsilon(Nd) of similar to-6. We argue that these peridotites not only melted, but were also re-enriched in compatible elements concurrent to melting in the past, and that such incompatible element re-enriched peridotites are now the main component of the sub-ridge mantle in the Sierra Leone area. Extensive remelting of ancient, incompatible element re-enriched peridotite that is compositionally buoyant, in addition to minor amounts of recycled crust, may therefore have caused the abundant magmatism that characterizes this portion of the MAR since formation of the Sierra Leone and Ceara Rise similar to 80 Ma ago, and accounts for its elevated topography.

The archaeological complex of Kafir Kala is one of the most important sites in the Samarkand oasis, strategically located just a few miles from the main city and along the major junction of the Silk Road. After more than twenty years of systematic archaeological investigation, the importance of Kafir Kala as a nodal point within the broader Eurasian connection network was recognised by its inclusion on the UNESCO World Heritage List in 2023 as part of the Silk Roads. During both the Pre-Islamic (second half of the 7th – early 8th century AD) and the Islamic (early 8th – 12th century AD) phases, ovicaprids were the predominant species in the faunal record. To date, stable isotope analysis from Uzbek archaeological sites is very limited, with no data available for fauna. Similarly, despite the region’s historical role in mobility and exchange, 87Sr/86Sr analysis has been applied in only a few archaeological contexts. Here, we present the results of a multi-proxy study including proteomic (Zooarchaeology by Mass Spectrometry - ZooMS) and isotope (87Sr/86Sr, δ13C, δ18O) analyses on twenty ovicaprid teeth from the Islamic phase of Kafir Kala to gain insights into the management strategies of the most represented species in the local faunal record. The identification of at least two different breeding strategies – marked by clear differences between sheep and goats – together with evidence of contacts with foreign groups, is consistent with enduring local traditions and further highlights the dynamic role of Kafir Kala at the crossroads of the ancient Silk Road trade networks.

Conodonts are extinct early vertebrates whose apatite oral elements provide one of the most extensive vertebrate fossil records widely used in biostratigraphy and paleoceanography. However, their trophic ecology and physiological differentiation remain poorly constrained. Here we investigate stable strontium isotope compositions (delta Sr-88) in six conodont genera from a well-preserved latest Famennian (Upper Devonian) succession at the Kowala Quarry (Holy Cross Mountains, Poland), spanning three conodont biozones. After detailed assessment of diagenetic preservation using crystallographic, elemental, and radiogenic Sr isotope data (Sr-87/Sr-86), we show that conodont bioapatite retains a primary biological delta Sr-88 signal. Statistically significant genus-level differences in delta Sr-88 are observed and persist after correction for stratigraphic trends. The studied genera cluster into two distinct groups, with Palmatolepis, Bispathodus, and Pandorinellina showing higher delta Sr-88 values than Branmehla, Mehlina, and Idioprioniodus. These differences are consistent with biologically driven isotope fractionation and likely reflect trophic niche differentiation and/or digestive physiology (vital effects) rather than diagenetic overprinting. Comparison with apparatus architecture indicates that delta Sr-88 variations correlate most strongly with P-1 element morphology: taxa with blade-like P-1 elements display lower delta Sr-88 values than those with platform-, icrion-, or expanded basal cavity morphologies. Our results demonstrate that stable Sr isotopes provide a novel proxy for reconstructing trophic structure and ecological differentiation in extinct marine vertebrate communities.

Among the key questions regarding oceanic transform and detachment faults are: (1) the depth extent to which they may develop and (2) the nature of their deepest shear zones. Here we investigate abyssal ultramafics dredged from the foot of an inside-corner high adjacent to the Andrew Bain transform valley on the Southwest Indian Ridge. The recovered suite includes plagioclase-bearing harzburgites and lherzolites, together with a plagioclase-rich hybrid rock. The peridotites are characterized by primary mantle-derived assemblages, overprinted 1–2 mm thick anastomosing porphyroclastic mylonite bands, and marked mineral heterogeneity. Mineral assemblages and composition indicate that shearing began during the transition from spinel- to plagioclase-peridotite facies conditions, at ca. 8 kbar and 1170–1150°C, in the presence of MORB-type intergranular melts. Further recrystallization of the shear zones terminated under melt-absent conditions at 900–800°C. Clinopyroxene compositions preserve REE signatures of weakly evolved MORB-like melts, whereas plagioclase compositions with An# 70–88 record interaction with variably evolved melt portions. The plagioclase-rich sample is interpreted as a local product of melt accumulation and melt-peridotite reaction, including late interaction with a primitive, plagioclase-undersaturated melt that produced reactional high-Al spinel. We interpret these rocks as recording deep, melt-influenced mantle shearing near a transform-detachment junction, most likely related to the detachment system rather than to strike slip transform faulting alone. Localized melt infiltration and heating at the end of the spreading segment may have weakened the lithospheric mantle, promoted grain-size reduction and helped establish melt-channelizing shear zones at depths > 20 km below the seafloor.

Following the end-Triassic biotic crisis, the first larger benthic foraminifera (LBF) emerged in shallow-water carbonate platforms of the Early Jurassic Tethys, during the Hettangian and Sinemurian. In inner-platform settings, these LBF frequently coexisted with large aberrant bivalves of the Lithiotis Facies, characterized by thick, gregarious accumulations. This study re-assesses the biostratigraphy of LBF and lithiotid bivalve faunas in a c. 200 m-thick Pliensbachian shallow-water sedimentary succession of the Rotzo Formation in the Trento Platform (Southern Alps, Italy). By integrating carbon and strontium isotope stratigraphy, we refine the chronostratigraphical framework for key LBF taxa that are widely used in Lower Jurassic carbonate platform biostratigraphy. Strontium isotope stratigraphy reveals that Orbitopsella primaeva first occurs in the lowermost Pliensbachian Jamesoni Zone, younger than the late Sinemurian age typically cited. Similarly, the last occurrence of Orbitopsella praecursor is in the lowermost upper Pliensbachian (early Margaritatus Zone), later than the traditionally accepted uppermost lower Pliensbachian. This study also constrains the timing of the appearance, development and demise of lithiotid bivalve associations in the Trento Platform. Lithioperna first appears in the lowermost Pliensbachian Jamesoni Zone, followed by Opisoma near the boundary between the Jamesoni and Ibex zones. Higher in the succession, Lithiotis becomes prominent near the Davoei-Margaritatus zone boundary, forming thick accumulations intercalated with brachiopod-rich beds. The final phase of the Lithiotis Facies is marked by Cochlearites-Lithioperna mounds, starting from the Subnodosus Subzone of the Margaritatus Zone. The disappearance of the lithiotid bivalves coincides with the onset of relatively deeper water conditions at the Rotzo Formation-Misone Limestone boundary in the uppermost Pliensbachian Spinatum Zone.

Straight-tusked elephants (Palaeoloxodon antiquus) were the largest land mammals of the European Pleistocene. Abundant fossil remains have been recovered from Neumark-Nord [~125 thousand years ago (ka); Saxony-Anhalt, NE Germany], where over 70 individuals were accumulated by Neanderthal hunting and butchering activity. This study reconstructs the species' paleoecology using a multiproxy approach that combines isotopic and paleoproteomic analyses of tooth enamel. LA-MC-ICPMS 87Sr/86Sr analyses on molar cross sections from four adults reveal subseasonal mobility over periods up to eight years. A specifically developed Sr isoscape facilitates tracking of elephant movements, using Bayesian analysis to map their Last Interglacial homerange. Amelogenin proteomic analysis identified three males and one likely female. Two male elephants exhibit elevated 87Sr/86Sr profiles, distinct from the local bioavailable ratios. Intra-tooth δ13C and δ18O analyses provide insights into paleodiet and drinking water sources, differing between individuals with low and elevated 87Sr/86Sr. The latter likely foraged up to 300 km away before arriving at Neumark-Nord, where they were ultimately killed and processed by Neanderthals.

During the Holocene, Eastern Sudan functioned as a cultural and ecological crossroads throughout northeastern Africa. However, despite its significance, the region has remained largely unexplored in terms of human mobility studies through isotope analyses. This research addresses this gap by analysing ⁸⁷Sr/⁸⁶Sr ratios in human and faunal remains from three key archaeological sites – Upper Atbara 50 (UA50), Upper Atbara 53 (UA53), and Mahal Teglinos (K1). Spanning five cultural phases and over four millennia – UA50, Malawiya Group (second half of the 5th millennium BCE); UA53, Butana Group (late 4th millennium BCE); K1, Gash Group (early 3rd –early 2nd millennium BCE); Jebel Mokram Group (early 2nd millennium BCE–early 1st millennium CE); and Hagiz Group (first half of the 1st millennium CE) – these data offer novel insights into the diachronic patterns of mobility and interaction that shaped the Eastern Sudanese lowlands during the Mesolithic and the Neolithic. Results reveal a complex diachronic pattern of human mobility. High levels of individual mobility during the late Mesolithic likely reflect a nomadic lifestyle, which progressively shifted towards greater sedentism in the Neolithic, associated with the adoption of agriculture and animal husbandry, as well as the establishment of larger sites. In the 3rd and 2nd millennia BCE, the site K1 likely functioned as a key regional hub, facilitating interactions between different communities, as evidenced by the adoption of diverse funerary practices and the wide range of ⁸⁷Sr/⁸⁶Sr isotope signatures among individuals identified as mobile. From the 2nd millennium BCE, harsher environmental conditions and shifts in socio-economic dynamics in northeastern Africa prompted a return to more nomadic pastoral lifeways. In Eastern Sudan, proximity to the Ethio-Eritrean highlands may have mitigated the effects of aridification, making this region a potential shelter region that attracted groups from the Eastern Desert, where environmental stress was likely more severe or occurred earlier. This study establishes a preliminary isotopic baseline for Eastern Sudan and provides new insights into long-term patterns of mobility and interaction. It complements existing archaeological data and offers a robust framework for future multidisciplinary investigations into exchange networks and cultural resilience in this pivotal region of northeastern Africa.

Alpine Upper Palaeolithic contexts exhibit specialised subsistence strategies, heavily dependent on Capra ibex. Among them, the rock shelter Riparo Dalmeri stands out, with C. ibex dominating faunal remains across all occupation phases, spanning the Pleistocene-Holocene transition. This evidence positions Riparo Dalmeri as a key site for exploring the interaction between human groups and C. ibex during this period of significant climatic and cultural shifts in human evolution. Here, we present the first multidisciplinary study on Late Palaeolithic C. ibex teeth from Riparo Dalmeri, integrating direct radiocarbon dating, stable isotope (δ13C, δ18O) and 87Sr/86Sr analyses, proteomic, and aDNA data. We generated the earliest aDNA sequences for C. ibex and contextual evidence on mobility, seasonality, and sex ratios. We found that most C. ibex were local to the area despite consistent human presence. They reveal significant dietary differences between sexes as well as increased seasonality at the Pleistocene-Holocene transition. Our results identify Riparo Dalmeri as belonging to an extinct branch of the ibex mtDNA phylogeny, offering unprecedented insights into ibex ecology and evolution that resonate with present-day issues on the conservation of this species in the face of climate change.

The trajectories of human and object mobility in the 3rd and 2nd millennia BC have long been a significant area of inquiry within prehistoric archaeology and over the past decade, aDNA and isotope analyses revealed a complex pattern of human migration, cultural admixture and exchange routes. While Northern Italy is clearly involved in this phenomenon, there remains a significant gap for the south of the country, generally considered peripheral to major exchange networks in this phase. Recently, two large cemeteries have been discovered in the hinterland of Mount Vesuvius (Acerra, Italy). They have yielded unprecedented numbers of exotic metal objects dating to 2400-1800 BC. Such items are extremely rare in Southern Italy, displaying typologies more commonly found across Northern Italy and Central Europe. Archaeological, bioanthropological and geochemical methods were applied to material from the cemeteries. Pb isotope analyses and metal artifact distribution modeling revealed long-distance terrestrial and maritime connections to Northern Italy, Continental Europe and the Western Mediterranean. Conversely, Sr isotope data indicate that these prestigious and exotic objects were deposited within a context of low human mobility. By integrating investigations into both metal and human mobility, this study emphasizes the extent and complexity of the exchange network in Southern Italy around 2000 BC.

The Sr and Ca isotope composition, along with trace element content in fossil teeth, provides valuable insights into biogenic and diagenetic processes. Identifying pristine biological signals is crucial for reconstructing the diet and trophic levels of extinct taxa. We present novel geochemical data from Tyrannosauridae and Ceratopsidae teeth of the Late Cretaceous, using radiogenic Sr (87Sr/86Sr), stable Sr (588/86Sr), and Ca (544/42Ca) isotopes, along with trace elements abundances to differentiate biogenic signals from diagenetic alteration. Our results reveal potential taxon-specific diagenetic effects, likely influenced by enamel microstructure. Tyrannosaurid enamel contains lower concentrations of rare earth elements (REE) and uranium (U) than dentine, whereas ceratopsid teeth typically exhibit higher REE and U compared to both the enamel and dentine of tyrannosaurids. Enamel 544/42Ca values differ significantly between herbivorous ceratopsids and carnivorous tyrannosaurids, reflecting trophic level effects seen in modern mammals and reptiles. A positive correlation between 544/42Ca and 588/86Sr suggests partial preservation of biological fractionation along the trophic chain. Yet, the lack of negative 588/86Sr values in our dataset - typically expected in biologic tissues - suggests alteration by diagenetic processes of both stable and radiogenic Sr. While 544/42Ca in enamel likely remains a reliable dietary proxy, Sr isotope composition of our samples appears then to be significantly altered. The presence of high 588/86Sr in terrestrial fossil teeth could serve as a novel diagenetic proxy to assess habitat related 87Sr/86Sr values, aiding provenance and mobility studies in fossil ecosystems.

Reconstructing the trophic (paleo)ecology and associated physiological traits of both extinct and extant taxa is essential for understanding the functioning of (past) ecosystems. In this context, novel metal stable isotope proxies offer promising tools for investigating ancient diets and, to some extent, the digestive adaptations of animals. In this study, we analyzed the stable strontium isotope composition (delta Sr-88), alongside delta C-13, delta O-18, and Sr-87/Sr-86 ratios, in fossil dental remains of herbivorous mammals from the Early Pleistocene site of Tighennif, Algeria (similar to 1.2-1.0 Ma). Traditional carbon and oxygen isotope data indicate an environment dominated by C-3 vegetation, while the Sr-87/Sr-86 ratios suggest either a relatively homogeneous strontium baseline or limited geographic mobility of the animals. Our results demonstrate that delta Sr-88 is sensitive to diagenetic alteration, with enamel samples retaining biogenic signatures comparable to those of modern mammals, whereas dentine exhibits delta Sr-88 values shifted toward positive geogenic end-members. delta Sr-88 patterns may reflect trophic niche differentiation among herbivores and potentially indicate distinct digestive physiologies, offering a novel alternative proxy for dietary and ecological reconstructions in the fossil record.

Bioavailable strontium (Sr) isoscapes are essential tools in studies on environmental processes, animal and human mobility and provenance. The success of these studies relies on the comparison between the measured 87Sr/86Sr isotope ratios of specimens and the spatial distribution of environmental bioavailable Sr isotopic signatures across geographical regions. A critical step of this process is the construction of reference maps that integrate environmental Sr isotopic data with geographical information. Here, we present a new bioavailable Sr dataset of 113 environmental samples, including plants and malacological samples collected from center-east Argentina (Paraná Delta, Pampa and Entre Ríos plains) as well as adjacent Uruguay, covering an area of approximately 122,500 km2. This dataset is further integrated with archaeological bioapatite data from the literature to construct the first random forest-based Sr isoscape of the region. Notably this area is on recent Quaternary (fluvial, marine and aeolian) sediments derived from the erosion of magmatic and metamorphic terrains with different Sr isotope composition from low 87Sr/86Sr ratios (about 0.706) to highly radiogenic signatures (>0.71), and heterogeneously transported in the Delta area by the rivers and in the high plains by wind and rivers. This isoscape offers a unique perspective on the Sr isotope distribution in a lithologically homogeneous region characterized by relatively young sedimentary sequences. This work represents a significant advancement in the development of Sr isoscapes, providing a fundamental tool for environmental and archaeological applications in South America.

Basin-scale dolomitization of carbonate sequences occurs over long time spans and results from diagenesis, burial, and tectonically driven fluid fluxes. Depicting the different geological processes producing dolomitized carbonate sequences requires combining accurate field, petrographic, and geochemical analyses. Here, we investigate the dolomitization processes in carbonates of the Norian to Toarcian age exposed in the Gran Sasso Massif, Central Apennines of Italy, by integrating field observations, standard and CL petrography, carbon, oxygen, strontium and clumped isotopes, minor elements, and X-ray diffractometry. The carbonates show pervasive replacive dolomitization, and dolomite cements are observed in bed-parallel and thrust-related veins. Replacive dolomites show incomplete replacement from modified seawater in oxidizing conditions, with minimum temperatures of 40–65 °C and a 87Sr/86Sr lower than coeval seawater. The first dolomitization event started at shallow burial in the Late Triassic–Early Jurassic and was later affected by replacement at intermediate burial depths. Bedding-parallel dolomite veins crystallized due to fluid overpressures at deep burial depths in a rock-buffered system without variations in geochemistry. Fault-related dolomites cemented thrust-related fractures during compressional deformation in the Messinian–Early Pliocene from seawater modified by mixing with external fluids. Precipitation temperatures of replacive, bedding-parallel, and fault-related dolomite veins are similar. Despite the dolomite types being characterized by different textures and petrographic features, rock-buffered conditions resulted in insignificant variations of their geochemical properties.

Fault-related diagenesis critically influences the petrophysical and mechanical properties of fault zones, affecting fluid circulation and seismicity in the upper crust. Questions remain about the composition of the mineralizing fluids and the role of fault architecture in controlling the distribution of hydrothermal silicification. This study addressed these questions by establishing the source of hydrothermal fluids and documenting the spatial variability of synkinematic hydrothermal products along the Kornos-Aghios Ioannis fault (Lemnos, Greece). The Kornos-Aghios Ioannis fault is an similar to 10-km-long extensional fault system that deforms, at shallow depth (<1 km), Eocene-Miocene sandstone turbidites and volcanic rocks. Our multidisciplinary approach, combining structural analysis, petrography, mineralogy, geochemistry, and fluid inclusion microthermometry, revealed that silicification occurred in an epithermal environment assisted by the circulation of acid-sulfate hydrothermal fluids (temperature similar to 160-170 degrees C). Mineralizing fluids were predominantly meteoric in origin, with a possible residual magmatic component. The intensity of silicification decreases with distance from the principal slip surface, forming up to 250-m-thick rock volumes that, locally, outsize the width of the fault damage zone. Along the fault strike,only an similar to 4-km-long fault segment exhibits silica cementation. This along-strike variability is best explained by the long-term evolution of the fault system. Kilometer-scale soft-and hard-linkage patterns combined with second-order geometric complexities (e.g., breached relay ramps and tips) localized fluid flow and promoted extensive alteration. Our findings have implications for the understanding of the permeability structure of silica-cemented fault zones, with relevance for the assessment of seismic hazards and exploration of natural resources in siliciclastic rocks.