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The Mediterranean Basin has been subjected to important geological and paleogeographic events that have shaped the evolution of the faunal assemblages that inhabit it. Two main events can be highlighted, the closure of its eastern margin by the Gomphotherium Land Bridge, and the temporal closure of the connection to the Atlantic Basin during the Messinian Salinity Crisis. These two events shaped the diversity of the chondrichthyan assemblages of the Mio–Pliocene Mediterranean, and their consequences can be observed even in the modern faunal composition. To better understand the taxonomic and ecological composition of the Mediterranean chondrichthyan faunas between the aforementioned events, and how they affected their evolutionary dynamics, we have performed a complete systematic and paleoenvironmental study of the chondrichthyan assemblage recovered from various Late Miocene localities at the municipality of Alcoy Basin (Alicante, eastern Spain). Our analysis allowed us to recognize up to 20 taxa of sharks and rays recovered from Miocene deposits. In addition, we reconstruct the paleobathymetry of the El Muro fossil site, based on the estimation of the Oceanization Index for foraminifera, as well as by the elasmobranch fossil assemblage via weighted bootstrap analysis. We expect that this first description and study of the Miocene chondrichthyan taxa from this area of eastern Spain could help us create a comparative framework to compare these communities with other areas, as well as show the changes in the elasmobranch species that have inhabited the Mediterranean Basin during and after the Messinian Salinity Crisis. [ABSTRACT FROM AUTHOR]

The application of stable isotope analyses allows a diachronic characterisation of species habitat and feeding behaviour, information of utmost importance for zooarchaeological research. In South America, the former distribution of the guanaco (Lama guanicoe) encompassed a much larger territory than the current one. Within the Argentinean Great Chaco, only a small native population persists in Northwestern Córdoba province, Central Argentina, where it was once widely distributed. In this paper, we present the first set of dentin and collagen δ13C and δ15N values for this relict population (N = 18) along with archaeological data of guanaco specimens (N = 19) dated to the Middle and Late Holocene from the nearby Ongamira valley. Neither deciduous and permanent teeth nor males and females show marked differences within the modern samples. Both modern and archaeological guanaco δ13C values indicate a mixed diet of C3 and, to a lesser extent, C4 plants. Conversely, the δ15N values exhibit distinct signals between the Arid and the Mountain Chaco subregions. The diet breadth of the archaeological guanacos suggests the use of transitional or ecotonal environments, also reflected in the size of their isotopic niche as opposed to modern guanacos. Regarding the timing of the species retraction in the region, there is no evidence of a shift in its habitat during the period between ~4700 and 190014C years BP. We suggest their retraction probably occurred later than previously proposed in regional zooarchaeological models. [ABSTRACT FROM AUTHOR]

Inertinite, as an important and abundant maceral group in coal, is critical for the study of palaeowildfires and their roles in the Earth's ecosystems. Recently, there has been a significant amount of research on the relationship between palaeowildfire, palaeoclimate change and palaeovegetation evolution based on inertinite data. The reflectance of fusinite and semifusinite has been used to estimate the combustion temperature and type of palaeowildfires, and then to evaluate the combustion characteristics of different types of palaeowildfires. The relative abundance of inertinite can be used to estimate the atmospheric oxygen contents. The rapid development of artificial intelligence (AI) and online tools to search scientific databases has presented an opportunity for us to find, collect, arrange, and analyse data from the earliest to latest publications on inertinite. The data extraction tool Deep Shovel is used to collect and analyse global inertinite data from the Silurian to the Neogene. The software programs such as Gplates, ArcGIS pro and Tableau are then applied to model the relative abundance of inertinite over geological time, which can be correlated with other parameters such as atmospheric oxygen contents, plant evolution and palaeoclimate changes. The distribution of inertinite in coals varied over different geological periods, being typified by the "high inertinite content-high atmospheric oxygen level" period in the Permian and the "low inertinite content-low atmospheric oxygen level" period in the Cenozoic. This study has proposed a possible model of the positive and negative feedbacks between inertinite characteristics and palaeoenvironmental factors, and has revealed the exceptional role of inertinite in palaeoenvironmental studies. Future research on inertinite will be focused on the integrated study of organic petrology and organic geochemistry of inertinite, the big data-driven research on the temporal and spatial distribution of the global inertinite, the exploration of the functions of palaeowildfires in the Earth systems in different climatic backgrounds, and the study of modern wildfires to better predict the future frequency and intensity of wildfires due to climate changes. [ABSTRACT FROM AUTHOR]

• This study summarizes all existing and unpublished data on the Late Triassic plant fossils in Guangdong. • Four regional assemblages have been distinguished in the Late Triassic by marine fossils such as ammonites and bivalves. • The Late Triassic climate in the Guangdong region was mainly warm and humid, either tropical or subtropical. • During the Late Triassic, central and northern Guangdong were located at similar latitude, along the southern coastline of the South China Block. Triassic-Jurassic deposits are well developed in Guangdong Province, South China. In particular, the Upper Triassic coal-bearing strata which alternate between marine and terrestrial deposits yield diverse and abundant fossil plants, ammonites and bivalves. These strata provide a significant reference for the study of palaeoenvironmental variations in the lower latitude regions. In this paper, we review the major progress on Late Triassic floral studies in this area. Specifically, we compare the regional plant assemblages from different fossil sites in central and northern Guangdong which have been dated with marine fauna. 155 species belonging to 56 genera of fossil plants have been reported so far in northern and central Guangdong. The Late Triassic floras in Guangdong are mainly composed of Bennettitales and ferns, followed by horsetails, seed ferns, cycads, ginkgos and conifers. In ascending order, four regional plant fossil assemblages can be recognized in the Late Triassic deposits, namely the Pachypteris - Lindleycladus Assemblage (Julian), the Pterophyllum - Baiera Assemblage (late Julian), the Clathropteris - Otozamites Assemblage (Tuvalian), and the Danaeopsis - Anomozamites Assemblage (Rhaetian). In general, the Late Triassic climate in the Guangdong region was mainly humid and warm and either tropical or subtropical. The fossil plants corroborate palaeomagnetic evidence that the central and northern Guangdong region was located at approximately the same latitude as it is today and formed the southern coastline of the South China Block during the Late Triassic. Palaeogeographically, the transgression started at the end of the Julian and the south coastal terrane consisted of a western bay, a peninsula and an eastern bay. During the regression period, post-Rhaetian, the bays evolved into a gulf coastal plain. [ABSTRACT FROM AUTHOR]

Northeast China played an irreplaceable role in population migrations and cultural exchanges in East Asia during the Paleolithic. This paper collected 182 archaeological sites to analyse the characteristics of spatial-temporal variations of Paleolithic human activities in Northeast China, and explored the driving mechanisms behind these variations in combination with the paleoenvironmental and archaeological studies. During the Lower Paleolithic, constrained by the relatively cold-dry climate and blocked by the Songnen paleo-lake basin, the population was sparse and distributed only near 40° N at the southern end of Northeast China. Upon entering the Middle Paleolithic, as humans developed greater tolerance to cold climates and adopted more sophisticated survival strategies with the application of small lithic tools, their numbers increased and geographical distribution expanded northward to 45° N at the central region of Northeast China. The Upper Paleolithic saw a considerable increase in population and expansion across almost all of Northeast China except for the eastern Inner Mongolia Plateau. We speculated that 50 ka and 30 ka BP were two key points, both of which may be associated with a significant increase in the frequency of migrations and communications among humans, and the widespread popularity of highly mobile microblade technology, respectively. In addition, the environmental analysis of archaeological sites revealed a continuous spread of Paleolithic humans to areas with higher elevations, steeper slopes, and lower temperatures. Meanwhile, they were becoming less reliant on water resources and were more widely conducting activities in open-air areas, showing that the environmental adaptability had been continuously improving over time. This study can provide a reference for the reconstruction of the migration history of early humans in East Asia, and is also of great significance for a comprehensive understanding of the evolutionary process of early human-environment interactions. [ABSTRACT FROM AUTHOR]

This multidisciplinary study aims to decipher the impact of ancient charcoal production on past and present‐day soils in the northern Vosges Mountains. Soil observations in the field and laboratory were complemented by charcoal and phytolith studies on large thin sections, molecular analyses of organic pollutants, and phytolith analysis on bulk samples. The complex technosol platform records an ancient natural soil sequence buried by a human‐made platform on which charcoal accumulated. The current upslope soil is an entic Podzol. Palaeoecological data collected in the buried soil are reliable owing to low bioactivity due to soil acidity. Podzolisation predated the platform construction. The presence of ashes induced low soil alkalisation developed in the charcoal hearth remains and appears to have generated the migration of subsequent iron/clay/organic bands throughout the platform sediment and the buried soil. Charcoal studied in thin sections revealed mainly Quercus and Fagus taxa. Phytolith studies suggest that a less dense or degraded forest preceded platform construction, probably due to former woodland coppicing or earlier disorganised wood gathering. The specific distribution of polycyclic aromatic hydrocarbons sorbed on charcoal has persisted in soils throughout centuries, but we have no evidence that charcoal‐making activities contributed to diffuse global pollution. [ABSTRACT FROM AUTHOR]

This research was carried out in north-central Poland, which was occupied by the ice sheet of the Saalian (Marine Isotope Stage [MIS] 6) and Upper Stadial of the Weichselian (MIS 2) glaciation. The application of the anisotropy of magnetic susceptibility (AMS) method supported by a digital elevation model (DEM) analysis of the orientation of glacial landforms allowed for the reconstruction of ice-sheet extent and ice movement directions of these two Pleistocene glaciations. The research used an innovative method of collecting AMS till samples from the glacial plateau areas. Based on the research, it was found that during the general recession of the ice sheet of the Saalian glaciation, a previously undescribed glacial transgression occurred, characterized by a different direction of ice-sheet movement. On the basis of detailed geomorphological studies of the area of terminal moraines, previously described in fragments, the maximum extent of the ice sheet during the Weichselian glaciation was clarified. The recession of the ice sheet of the Weichselian glaciation from the area of north-central Poland took place in four regressive or transgressive–regressive stages with variable directions of ice-sheet movement. The results obtained indicate the great potential of the AMS method in paleoenvironmental studies of glaciated areas. [ABSTRACT FROM AUTHOR]

Changbaishan volcano (China/North Korea) is one of the most active and hazardous volcanic centers in Northeast Asia. Despite decades of intensive research, the eruption history of this stratovolcano remains poorly constrained. One of the major puzzles is the timing of the eruption that produced the Tianwen Yellow Pumice (TYP) deposit at the caldera rim. Here we identify a new cryptotephra layer in sediment core 13PT‐P4 from the East Sea. Grain‐specific major, minor, and trace element analyses of glass shards allow a clear correlation of this distal tephra to the proximal TYP deposit of Changbaishan. Age‐depth modeling using radiocarbon (14C) dates of sediment bulk organic fractions and other tephrochronological markers from the sediment sequence constraints the age of the cryptotephra and thus the TYP eruption to 29,948–29,625 cal yr BP (95.4% confidence interval). Our findings lead to a revision of the history of Changbaishan explosive activity, and show that the volcano has been particularly active during ca. 51–24 ka BP in the last 100 ka. Using high resolution palaeo‐proxy records, we find the TYP tephra almost coeval with regional to hemispheric‐scale climatic changes known as Heinrich Event 3 (H3). With its precise age determination and wide geographic dispersion, the tephra offers a key isochron for dating records of past climatic changes and addressing the phasing relationships in environmental response to H3 across East Asia. Plain Language Summary: Improving the knowledge of past volcanism is critical for volcanic hazard mitigation. Changbaishan volcano is one of the most dangerous volcanic centers in Northeast Asia, but its eruption history is not clearly understood. A classic example is the eruption that produced the magnificent Tianwen Yellow Pumice (TYP) deposited at the crater rim. Previous studies suggested a range of very different ages for this major eruption. In this study we trace its volcanic ash into a marine sediment core from the East Sea. By radiocarbon age‐depth modeling we are able to say with a high level of certainty that the eruption occurred sometime between 29,948 and 29,625 cal yr BP. The new results demonstrate the dispersal potential of ash from the eruption and shed light on the history and frequency of Changbaishan explosive activity. In addition, the TYP eruption is found to coincide with hemispheric‐scale and regional environmental changes. As a consequence, the volcanic ash can be used as a key time mark for dating sediment sequences and for investigating past environmental changes in East Asia. Our study also demonstrates the potential of using distal volcanic ash in reconstructing past explosive volcanism. Key Points: Timing of the Changbaishan Tianwen Yellow Pumice (TYP) eruption is resolved through proximal‐distal tephra correlation and radiocarbon age‐depth modelingEruption history of the Changbaishan volcano is revised, and dispersal potential of the TYP tephra is shown for the first timeA demonstration that the TYP tephra, as a regional marker, has great potential for sediment sequence‐based palaeoenvironmental studies [ABSTRACT FROM AUTHOR]

Ichnofossils have been defined for the first time from the rocks exposed along the Katilu Khad section, Dunera, Punjab (India) of Miocene succession. Eight ichnotaxa with 12 ichnospecies have been recorded, including Arenicolites isp., Beaconites coronus, Helminthopsis tenuis, Lockeia siliquaria, Palaeophycus tubularis, Palaeophycus isp., Planolites annularis, P. beverleyensis, Skolithos linearis, Taenidium barretti, T. cameronensis, and T. serpentinum. The present ichnofossil assemblages are recognised by two ichnofacies – Scoyenia and Mermia. Scoyenia ichnofacies is typified by less diversity but a high abundance of meniscate burrow (Taenidium and Beaconites), whereas Mermia ichnofacies shows high diversity grazing and feeding traces with low abundance. These ichnofacies indicate well-oxygenated, low-energy deposition exposed to air and represent the fluvial environment. [ABSTRACT FROM AUTHOR]

The analysis of phytoliths is a recent addition to the geosciences and has found applications in various fields over the last few decades, including palaeoenvironmental studies in fluvial environments. As a developing field, it is essential to carry out studies aimed at creating a modern reference collection that fills an information gap on the production of phytoliths by plants in this environment. These studies are essential to increase the reliability and accuracy of phytolith research in reconstructing past vegetation patterns and compositions. This study is the first with the aim of creating a pioneer collection of phytoliths in fluvial environments of the Upper Paraná River, addressing woody eudicotyledon species of greater representation on the Três Ilhas (Three Islands) Archipelago. The phytoliths were extracted from the leaves of 51 species from the botanical collection of the Nupélia herbarium (HNUP) using the dry ashing extraction method. The analysis found that 21 plant families established on the site have some kind of silica accumulation and 34 species are producers of phytoliths with an identifiable shape and size (<5um). It was confirmed the Moraceae family produces Acute bulbosus (with ramifications), both considered diagnostic at family level. Confirming the current literature on the subject, redundancy of the spheroid ornate and spheroid psilate morphotypes was observed in woody plants. Although no new morphotypes were found, the information will contribute to studies on the evolution of fluvial geoforms. [ABSTRACT FROM AUTHOR]

Charcoal is commonly preserved in both natural and artificial sediments, and is intensively used in paleontological, paleoenvironmental, and archaeological studies due to the abundant bio-information it contains. The biochemical properties of charcoal are also used for paleoclimatic reconstruction; however, the reliability of this approach has been challenged due to a lack of clarity on how physicochemical properties change during the charring process, as well as the temperatures required for charcoalification. To address this lack, in this study, Qinghai spruce and Chinese pine wood samples from the northeastern Tibetan Plateau were heated at different temperatures and for different lengths of time under restricted oxygen conditions. The reflectance; carbon, nitrogen, and oxygen content; and tracheid morphology were quantified before and after heating to assess changes related to the charring process. Archaeological charcoal remains were then evaluated to determine the charcoalification temperatures by comparing with the experimental results. The minimum temperature required for wood charcoalification was ~300 ℃, while temperatures recorded by archaeological charcoal were concentrated at 400-500 ℃. During the charring experiments, the tracheid cell walls gradually homogenized, and tracheid cell wall thickness and lumen area decreased by ~20%. On average, 50% mass losses were observed; the carbon and oxygen content (% wt.) approximately changed from 47% to 60% and 48% to 35% respectively, while the nitrogen content (% wt.) fluctuated around 0.2%. The reflectance increased slightly from 0% to 0.5%. We propose that the charcoalification of wood tissue refers to charring (in restricted air) and carbonization (in the almost absence of air) when the wood is exposed to a heat source, which then finally transforms into a black, inert solid. This quantitative study provided valuable data and a thorough assessment of the process of wood charcoalification, as well as accurately estimated the feasibility of using charcoal physicochemical properties in paleoclimatic research. [ABSTRACT FROM AUTHOR]

Europium (Eu) in coal and sedimentary rocks has important mineral resource potential as well as being a crucial parameter in geochemical studies that can represent changes in the depositional environment during coal deposition and identify the depositional source region. Therefore, it is essential to realize the precise measurement of Eu in coal as this could be a useful parameter for paleoenvironmental reconstruction studies and the exploration of mineral resources. During inductively coupled plasma mass spectrometry (ICP-MS) analysis, polyatomic ions of Ba may interfere with Eu, causing the observed value to be higher than the actual value. This paper develops a new approach for Eu determination by using a high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The mass spectral interference and correction of Eu in the coal and sedimentary rock samples at low, medium, and high resolutions were investigated. The results showed that in the high-resolution mode (resolution = 10,000 amu), the interference of polyatomic ions of Ba could be distinguished from Eu; hence, Eu was determined under this circumstance. Under the optimal experimental circumstances, the detection limit was 0.006 μg/mL, the relative standard deviation was 0.80%–1.22%, and the linear correlation coefficient of the standard curve was over 0.9999. The recoveries of the 103Rh internal standard solution ranged from 94.41% to 100.10%. This method was verified using standard reference materials and selected samples, which demonstrated its high sensitivity, accuracy, and reliability, and a low detection limit, making it appropriate for detecting Eu in samples of coal and sedimentary rocks. [ABSTRACT FROM AUTHOR]

The Northern Mesoamerican Frontier was a complex multicultural region characterized by frequent human settlement changes and shifts in agricultural conditions during the Late Preclassic period (~400 BCE-150 CE). Here, we report a high-resolution paleoenvironmental record from the varved sedimentary sequence of the crater maar La Alberca which spans the Late Preclassic (~400 BCE-150 CE) to part of the Early Classic period (~150 CE-250 CE) corresponding to Late Chupicuaro phase (400 BCE-100 CE) and Mixtlan phase (0–250 CE). Our work aims to study the paleoenvironmental conditions during the rise of agriculture in the Northern Mesoamerican Frontier and provide insights related to landscape alteration by human activity. To reach these aims, a multiproxy investigation was conducted by means of varve counting, high-resolution XRF scans, magnetic susceptibility, pollen data and fecal stanol biomarkers as a proxy for human population change. Our results reveal two varve type. Type 1 is characterized by the alternation of detrital-organic layers and aragonite layers, type 2 by alternating detrital-organic layers with an organic layer formed by diatom frustules and aragonite layers. This study suggest that the increase of erosion by human activity during the Late Chupicuaro phase (400 BCE-100 CE) and the start of the Mixtlan phase (0–250 CE) coincide with a high percentage of Amaranthaceae pollen, a rise of sedimentation rates, increase in nutrient content and the increase of human waste flux interpreted with the (Coprostanol + epi) :((Coprostanol + epi)+cholestanol biomarker. Moreover, a wetter period (~137 BCE-37 CE) interpreted during the Late Chupiacuaro phase and the start of the Mixtlan phase could suggest favorable environmental conditions for the establishment of agriculture. [ABSTRACT FROM AUTHOR]

Sedimentary records from the Kumtag (also known as Kumtagh) Desert (KMD) in northwestern China are investigated to better understand Late Quaternary paleoenvironmental changes in this hyper-arid region. Presented here are the results of probably the first systematic survey of sedimentary sequences from the KMD, with the chronology determined by the optically stimulated luminescence dating. The variation of sedimentary facies, supported by granular and geochemical paleoenvironmental proxies, is used to decipher the history of Late Quaternary environment changes. The results demonstrate that a constantly dry condition characterized the eastern KMD since the last glacial maximum, but with occurrences of wetter periods. From ca. 17 to 15 ka, fluvial activity was probably triggered by melting of glaciers in mountains located south of the KMD. A distinctly drier stage (ca. 13–7 ka) was recognized due to the prominent occurrence of aeolian sands. A wetter environment likely persisted between ca. 4.4 and 2.2 ka, consistent with evidence of human activities. While the causes of paleoenvironmental changes in the eastern KMD are still a matter of debate, the melting of glaciers in the Altyn-Tagh Mountains in the south must be considered as an important factor. [ABSTRACT FROM AUTHOR]

• Variable pollen-phytolith preservation, production, dispersal affect interpretation. • Modern pollen-phytolith assemblages reflect the varying vegetation composition. • Pollen and phytolith proxies do not track same primary vegetation signals. • Pinus was overrepresented in the samples across the plots except in the forests. • Modern pollen-phytolith assemblages can improve palaeoenvironmental interpretations. In palaeoenvironmental reconstructions, few studies have focused on comparing the presence of pollen and phytoliths in surface sediments to the local vegetation. Notwithstanding inherent differential pollen and phytolith preservation, production, and dispersal, which affect their recovery and interpretation in sediment archives, there remains a need to explore modern pollen-vegetation, phytolith-vegetation and pollen-phytolith relationships to improve palaeoenvironmental reconstructions. We carried out palynological and phytolith analysis on six surface sediment samples linked to the botanical survey of five vegetation survey plots at Gustav Klingbiel Nature Reserve, Mpumalanga province in northeastern South Africa, to understand the relationships between the modern pollen and phytolith assemblages in the surface sediments and the contemporary vegetation of the study area. Correspondence Analysis (CA) was undertaken to examine the fingerprint of the local vegetation in the modern pollen-phytolith assemblage and evaluate whether the phytolith and pollen assemblages were tracking each other. CA illustrated that pollen and phytolith proxies are not tracking the same primary vegetation signals; modern pollen assemblages best represent the components of forest and wetland vegetation. In contrast, modern phytolith assemblages best represent grassland vegetation. Our study shows that differential pollen and phytolith preservation, production and dispersal significantly affect sediment records more than anticipated, thus combining multi-proxies (e.g., phytoliths, pollen) provides a more accurate basis for the interpretation of fossil spectra in palaeoenvironmental reconstructions. [ABSTRACT FROM AUTHOR]

One of the most abundant species of bivalves found on modern beaches and Quaternary deposits in the San Matías Gulf (Argentinian Patagonia, SW Atlantic Ocean) is Glycymeris longior. Its high abundance and broad geographical distribution turn G. longior into a target species for taphonomical studies. Here, we described the taphonomic signature registered on its shells from San Antonio Bay (San Matías Gulf, Río Negro). This study will contribute to future taphonomic comparisons in the SW Atlantic Ocean, as well as in other Quaternary deposits, and provide insight into the spatial variation of the taphonomic processes influenced by the environment. Glycymeris longior valves from the Holocene Punta Delgado deposits showed two taphonomic signatures whose shell assemblages were differentiated by fragmentation, rounding and cementation intensities. Shells from PD2018A and PD2018B (two sampling localities representing similar environments) were subject to continuous and low-energy water flow. Those remained in a low-intensity hydrodynamic sediment-water interface that would favor high shell cementation. On the other hand, shells from PD2016 were also subject to continuous but more energetic water flow. Those would remain in the taphonomic active zone for enough time to confer smooth edges and to be colonized by clionid sponges but not favorable enough for carbonate precipitation. The Punta Delgado site was interpreted as a protected area during the Holocene (last 4200 yrs.), similar to the modern one, but with differences in carbonate precipitation as the product of differences in water flow intensities. Finally, the high mechanical resistance of G. longior shells, together with its abundance and broad geographical distribution, turn this species into a suitable target taxon for further taphonomic and ecologic analyses and comparisons. [ABSTRACT FROM AUTHOR]

An international, multidisciplinary research group is proposing the "NICA-BRIDGE" drilling project, within the framework of the International Continental Scientific Drilling Program (ICDP). The project goal is to conduct scientific drilling in Lake Nicaragua and Lake Managua (Nicaragua, Central America) to obtain long lacustrine sediment records to (a) extend the neotropical paleoclimate record back to the Pliocene, making it one of the longest continental tropical climate archives in the world, and to (b) provide geological data on the long-term complex interplay among tectonics, volcanism, sea-level dynamics, climate change, and biosphere. The lakes are the two largest in Central America, and they are located in a trench-parallel half graben that hosts the volcanic front, which developed during or prior to the Pliocene, as a consequence of subduction-related tectonic activity. The lakes are uniquely suited for multidisciplinary scientific investigation as their long, continuous sediment records (several Myr) will facilitate the study of (1) terrestrial and marine basin development at the southern Central American margin, (2) alternating lacustrine and marine environments in response to tectonic and climatic changes, (3) the longest record of tropical climate proxies, (4) the evolution of (and transition between) the Miocene to Pliocene/Pleistocene and Pleistocene to present volcanic arcs, which were separated by slab rollback, (5) the significance of the lakes as hot spots for endemism, and (6) the Great American Biotic Interchange at this strategic location, i.e., the N–S and reverse migration of fauna after the land bridge between the Americas was established. The planned ICDP project offers an opportunity to explore these topics through continent-based seismological, volcanological, paleoclimatological, paleoecological, and paleoenvironmental studies, combined with an International Ocean Discovery Program (IODP) drill project to explore its oceanic continuation. In preparation of this drilling project, an ICDP workshop was held in Montelimar, Nicaragua, on 2–5 March 2020 to develop drilling strategies and refine scientific questions, objectives, and hypotheses. The workshop was organized and hosted by the principal investigators and the Instituto Nicaragüense de Estudios Territoriales (INETER), with funding from the ICDP. Forty-five researchers from 12 countries participated in the workshop, including representatives from ICDP. During the workshop, previous research data on the study lakes, including new recent surveys, were reviewed, and a three-phase strategy for the proposed research was developed. The aim of Phase 0 is to complement the pre-site surveys where we identified the need for further data. In Phase I, with ICDP support, we will obtain sediment cores ∼ 100 m long, which will allow us to investigate many of the scientific questions. Based on the data from those drill cores, coring locations will be identified for a future Phase II, which we envisage as a combined ICDP/IODP project to collect deep drill cores in the lakes and the offshore Sandino Basin in order to extend Phase I results to much deeper time. The Sandino Basin is the oceanic continuation of the depression in which the studied lakes are located, and complementary marine drilling will improve the understanding of the evolution of this complex margin. [ABSTRACT FROM AUTHOR]

Foraminifera are widely used in paleoclimatic and paleoceanographic studies, providing information about past ocean conditions. However, in order to use these tracers, it is essential to obtain an accurate chronology. Radiocarbon has proven to be a powerful tool in developing robust chronologies. Sample sizes of a few milligrams of carbonate material are needed for precise radiocarbon determination using accelerator mass spectrometry (AMS). In the specific case of paleoceanographic and paleoenvironmental studies, Foraminifera microfossils are the most important indicator of oceanic conditions. However, for establishing the chronology of deposition, sample availability is often limited. In AMS facilities using solid ion sources, such as the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF), in Brazil, CO2 samples need to be converted to graphite after physical and chemical pre-treatment to remove contamination. Reducing the sample sizes increases the relative contribution of contamination and can favor increased background levels. In this work, we tested different amounts of 14C-free carbonate samples as a means to evaluate the pattern of contamination. For the sealed tube Zn/TiH2 graphitization method, we tested prebaking the graphitization tubes and compared storage procedures. As a result, the background for regular-sized samples was decreased, and accurate measurement of carbonate samples containing ca. 0.5 mg C could be performed. Prebaked graphitization tubes can safely be stored in desiccator cabinets for up to 4 weeks. Foraminifera samples with mass as low as 1 mg (ca. 0.1 mg C) can now be measured at the LAC-UFF AMS facility, provided that C contamination can be estimated and corrected. The developments presented in this work allowed for the study of species-specific Foraminifera and other small-sized carbonate samples. [ABSTRACT FROM AUTHOR]

This paper examines the palaeoenvironmental conditions of a Late Pleistocene marine unit assigned to the Puente de Pascua Formation (MIS 5e), Buenos Aires, Argentina. For this study, a micropalaeontological (Phylum Foraminifera) and lithological analysis was conducted, based on a PPas-section extracted in the Puente de Pascua site, located 32 km inland from the coastline of Bahía Samborombón (35°55′37” S; 57°43 ′7.6” W). The base of this section comprises finely stratified with brown clays, followed by a layer of dark brown sandy sediments with layers of shells, interspersed with light brown to yellowish deposits. Hyaline foraminifera of relative well preservation and small size prevail. The assemblage was represented mainly by Buccella peruviana and Ammonia parkinsoniana accompanied by other species such as Elphidium galvestonense, Ammonia tepida, Cribroelphidium poeyanum and Bolivina spp. in minor proportion. From this integrated study, palaeoenvironmental changes were established in Puente de Pascua Fm. (>66.5 kyrs). Results reflect transition from a tidal flat depositional environment towards a littoral estuarine environment. [ABSTRACT FROM AUTHOR]

In recent years, paleodietary and paleoenvironmental studies have made great progress due to new techniques, such as the analysis of dental wear at micro and macro level and the analysis of stable isotopes of different elements in animal tissues. Recently, the combination of these proxies has substantially improved these types of studies, however, these analyses go hand in hand with biology and the animal behavior, so it is essential to understand the species studied previously. This paper describes the analyses commonly used in recent years in the Columbian mammoth (Mammuthus columbi) and the relationship that the biology of this species has with the correct application of these analyses. Likewise, the samples and measurements taken from these fossil individuals must be taken with care, since the peculiarities in dental ontogenesis, behavior and metabolism are key to the comprehension of the results obtained. [ABSTRACT FROM AUTHOR]

Lagoon-specific local marine reservoir effects (ΔR lagoon) were defined as a new proxy to estimate the radiocarbon (14C) activity change in the lagoon freshwater proportion [1]. In Tongatapu island, previous research showed that ΔR lagoon values increased linearly between ∼2.6 and 0.4 ka, which suggested that ΔR lagoon value increase was caused by the near-closure of the Fanga 'Uta Lagoon [1]. However, the calculated values contained large errors. Here, we refine those study results and present 26 new 14C values from G. tumidum combined with the previously published values and a ΔR lagoon value recalculated using Marine20. Moreover, we investigated whether the 14C value of G. tumidum reflected that of the dissolved inorganic carbon in the lagoon water. Although the new ΔR lagoon values were similar between 0.4 ka and 1.2 ka, the values increased from 2.6 ka to 1.2 ka. This timing was consistent with geophysical comparisons reported in our previous study and archaeological studies. [ABSTRACT FROM AUTHOR]

The southern Central Andes–or Puna–now contains specialized plant communities adapted to life in extreme environments. During the middle Eocene (~40 Ma), the Cordillera at these latitudes was barely uplifted and global climates were much warmer than today. No fossil plant remains have been discovered so far from this age in the Puna region to attest to past scenarios. Yet, we assume that the vegetation cover must have been very different from what it looks today. To test this hypothesis, we study a spore-pollen record from the mid Eocene Casa Grande Formation (Jujuy, northwestern Argentina). Although sampling is preliminary, we found ~70 morphotypes of spores, pollen grains and other palynomorphs, many of which were produced by taxa with tropical or subtropical modern distributions (e.g., Arecaceae, Ulmaceae Phyllostylon, Malvaceae Bombacoideae). Our reconstructed scenario implies the existence of a vegetated pond surrounded by trees, vines, and palms. We also report the northernmost records of a few unequivocal Gondwanan taxa (e.g., Nothofagus, Microcachrys), about 5,000 km north from their Patagonian-Antarctic hotspot. With few exceptions, the discovered taxa–both Neotropical and Gondwanan–became extinct from the region following the severe effects of the Andean uplift and the climate deterioration during the Neogene. We found no evidence for enhanced aridity nor cool conditions in the southern Central Andes at mid Eocene times. Instead, the overall assemblage represents a frost-free and humid to seasonally-dry ecosystem that prevailed near a lacustrine environment, in agreement with previous paleoenvironmental studies. Our reconstruction adds a further biotic component to the previously reported record of mammals. [ABSTRACT FROM AUTHOR]

Analysis of phytoliths (plant silica bodies) still may have an unrevealed potential in paleoenvironmental reconstruction studies. This can provide novel findings in research on environmental change as phytoliths play an important role in the silicon biogeochemical cycle. In favorable environmental conditions, Picea abies [L.] H. Karst (Norway spruce) needles develop a phytolith layer consisting of more or less cubical or cuboid (blocky) phytoliths in their transfusion tissue that becomes continuous toward the apex of the needle. This can be studied in situ in fossil (subfossil) needles under a stereomicroscope. This study reports the blocky-type phytolith preservation in fossil spruce needles in sediment sections of the lake Černé jezero (Bohemian Forest, Czech Republic). The oldest needle containing phytoliths was 7.8 cal ka BP. Despite differences in the Energy Dispersive X-ray (EDX) spectra of different age phytoliths, the studied subfossil phytoliths did not lose their globular ultrastructure in the needle tissue, proving the stability of this phytolith morphotype. As the tissue of the needle fossils can preserve phytoliths in situ, further micro-analytical measurements will make these needles promising tools for paleoenvironmental reconstructions. The most favorable period for spruce phytolith formation for the studied region appears to be the period 6.0–4.5 cal ka BP, within the Holocene Climate Optimum period. In order to use these phytoliths as a terrestrial climate proxy, the next step is to refine their sensitivity to environmental changes. [ABSTRACT FROM AUTHOR]

Santonian-Campanian tuffaceous siltstone, epiclastic siltstone, arkose, and fossiliferous mudstone occur in a 45-m-thick section of well 1-BRSA-37-RJS drilled in the southern Campos Basin, offshore SE Brazil. Well log data and petrographic and lithogeochemical data obtained from cutting samples were used to propose a schematic model of the volcano's sedimentary paleoenvironment. The volcaniclasts in the tuffaceous siltstone and epiclastic siltstone are scoria basalts, typical of spatter cones associated with monogenetic fields worldwide. The combination of these features with the petrographic ones of the arkoses found in the same well interval is likely to be related to volcaniclastic processes taking place on the continental shelf. Ratios between the immobile trace elements of the volcaniclastic rocks can be explained by mixing between sources in the upper continental crust adjacent to southern Campos and the scoria basalts extruded in the monogenetic fields. The little differentiated, olivine-rich basalts extruded from the scoria and spatter cones suggest a rising asthenosphere mantle extending from hundreds of kilometers eastwards till southern Campos in the Santonian-Campanian. This may have resulted in regional discordances in the Santonian, both in the Campos and Santos basins, and also places the petroleum systems in the southern Campos Basin under the thermal influence of such a rising asthenosphere in the Santonian-Campanian. [ABSTRACT FROM AUTHOR]

The Taravu valley, located in the south-west of Corsica, is one of the most extensive watersheds on the island. Recent paleoenvironmental studies allowed to restitute the chronostratigraphy of the two ponds in the lower valley. However, the paleogeographic evolution of this sector still remains largely to be specified. In order to reconstruct the transformations of the landscape of the lower Taravu valley during the Late Holocene (2250 BCE), we have developed an innovative interdisciplinary approach combining the methods of historical geography (ancient maps and aerial photographs), geoprocessing of topographic data (slope map and drainage map) that we associated with the results of an electromagnetic survey (EMI) and previous stratigraphic data. This synthesis enables the creation of a geomorphological map of the lower Taravu valley, to identify several major landscape changes since the Neolithic period (5800-3000 BCE), and to follow the evolution of the alluvial forms of the Taravu and the shore line since the end of the 18th c. CE. [ABSTRACT FROM AUTHOR]

Benthic foraminifera, ostracods and pteropods are reliable paleoenvironmental indicators in Quaternary deposits. However, in the Ceará Basin, on the Brazilian Equatorial Margin, these microfossils are poorly studied. This paper investigates environmental changes during the Pleistocene--Holocene transition in the Icaraí subbasin based on micropaleontological analysis of the core ANP 1011. Seventy-four taxa of benthic foraminifera, represented predominantly by Globocassidulina, Uvigerina, Pyrgo and Melonis, have been identified. The ostracod assemblages are composed mainly by the families Macrocyprididae, Cytheruridae, Trachyleberididae, Pontocyprididae and Krithidae, of which the genus Krithe was the most abundant. The composition of the ostracod assemblages identified in this study area differs somewhat from other regions of the Brazilian Margin. The assemblages of foraminifera and ostracod characterize a typical bathyal paleoenvironment. The occurrence of pteropods and dominance of epifaunal foraminifera taxa, mainly Pyrgo sp. and Miliolinella sp. in the lower portion of the core (Pleistocene), indicates higher phytodetritus input and oxygen concentration. A conspicuous environmental change was observed in the upper portion of the core, which corresponds to the Holocene, where the increase of infaunal foraminifera (e.g., Uvigerina, Globocassidulina and Melonis) suggests reduction in the organic matter input and, probably, increased bacterial density and depletion in dissolved oxygen in the sediment. [ABSTRACT FROM AUTHOR]

We present a synthesis of the archaeological record at Los Viscos site, with an outstanding preservation of organic material, and analyze it in relation to the paleoenvironmental studies developed in El Bolsón valley, a high-altitude valley in Catamarca, Argentina, and the social landscapes inferred for the area. Los Viscos rock shelter has been occupied for the last 1200 years since Formative times. The material recovered there includes evidence of mixed production and resource procurement strategies over a great diversity of resources. Intensification in resource exploitation since the Regional Developments Period suggests novel constraints at the time. This record represents a period in which the palaeoenvironmental evidence suggests changes in the regional morphodynamics that prevented the preservation of other contemporary sites. Thus, Los Viscos provides a better understanding of production and consumption practices in the valley over the last two millennia. [ABSTRACT FROM AUTHOR]

The Jurassic–Early Cretaceous was a time of variable organic carbon burial associated with fluctuations of marine primary productivity, weathering intensity, and redox conditions in the pore and bottom water at paleo-shelf areas in north Egypt. This time interval characterized the deposition of, from old to young, the Bahrein, Khatatba, Masajid, and Alam El Bueib Formations in the north Western Desert. Although several studies have been devoted to the excellent source rock units, such as the Khatatba and Alam El Bueib Formations, studies on paleoenvironmental changes in redox conditions, paleoproductivity, and continental weathering and their impact on organic carbon exports and their preservation for this interval are lacking. This study presents organic and inorganic geochemical data for the Jurassic–Lower Cretaceous sediments from the Almaz-1 well in the Shushan Basin, north Western Desert. A total of 32 cuttings samples were analyzed for their major and trace elements, carbonates, and total organic carbon (TOC) contents. Data allowed the reconstruction of paleoenvironmental conditions in the southern Tethys Ocean and assessment of the changes in paleo-redox, paleo-weathering, and marine primary productivity, and the role of sediment supply. Additionally, factors that governed the accumulation of organic matter in the sediment were interpreted. Results showed that the Khatatba Formation was deposited during a phase of enhanced marine primary productivity under prevalent anoxia, which triggered enhanced organic matter production and preservation. During the deposition of the Khatatba Formation, significant terrigenous sediment supply and continental weathering were followed by a limited contribution of coarse clastic sediment fluxes due to weak continental weathering and enhanced carbonate production. The Bahrein, Masajid, and Alam El Bueib Formations were deposited during low marine primary productivity and prevalent oxygenation conditions that led to poor organic matter production and preservation, respectively. A strong terrigenous sediment supply and continental weathering predominated during the deposition of the Bahrein Formation and the lower part of the Alam El Bueib Formation compared to the limited coarse clastic supply and continental weathering during the deposition of the carbonate Masajid Formation and the upper part of the Alam El Bueib Formation. Such conditions resulted in the enhanced dilution and decomposition of labile organic matter, and, thus, organic carbon-lean accumulation in these sediments. [ABSTRACT FROM AUTHOR]

Through the analysis of seven 15–30 m deep boreholes drilled in the western sector of the Circus Maximus we reconstruct the aggradational history of one main tributary valleys of the Tiber River in Rome, the Murcia Valley (Vallis Murcia). Consistent with recent acquisitions in the Tiber Valley, we identify a Bronze Age (4500-3000 yr BP) paleogeographic setting characterized by the lowering of the drainage network base level. This would have created a dry alluvial plain, suitable for human settlement. We also find evidence for dramatic overflooding which occurred during the 6th century BCE and was responsible for the rapid rise from 2 to 6 m a.s.l. of the valley floors within the Tiber catchment basin in Rome. We suggest that these paleogeographic features can be identified in mythical and ethno-historical accounts of early Rome. Besides providing insights into the paleolandscape and anthropogenic interventions in the Murcia Valley, these previously unrecognized hydrological dynamics may attest to paleoclimatic fluctuation that have occurred since 5000 yr BP. Contrary to the dry and cold conditions prevalent during the Bronze through the Iron Age, the exceptional flooding events of the archaic period suggest a shift in climatic trends. However, tectonic and anthropogenic factors could have also had a combined and cumulative effect, requiring detailed paleoenvironmental and palaeolandscape studies. [ABSTRACT FROM AUTHOR]

The Kansk Basin is one of the biggest reserves of brown coal in Russia. Jurassic coal-containing terrestrial deposits bearing plant remains crop out in several localities. This work is focused on five fossil-plant-containing localities in the Middle Jurassic Kamala Formation of the Kansk Basin within the Rybinsk Formational Zone. The studied material comprises 29 plant morphospecies. They are assigned to: Pteridophytes (Equisetites , Coniopteris, Cladophlebis and Raphaelia), Bennettitales (cf. Pterophyllum), Ginkgoales (Ginkgoites, Sphenobaiera and Eretmophyllum), Leptostrobales (Czekanowskia and Phoenicopsis) and Coniferales (Pityophyllum). There are several plants remains of uncertain systematic position, such as roots (Radicites sp.), cones and fossil wood. As a result, palaeoenvironmental interpretation was implemented; three taphonomic units were distinguished utilising complex palaeobotanical, lithofacial analyses, and literature-based data. Palaeoecological analysis identified three depositional environments with corresponding type of vegetation: a) periodically flooded alluvial plain dominated by Czekanowskia-Phoenicopsis ; b) swamp-semiaquatic dominated by Equisetites, Coniopteris, Cladophlebis and Phoenicopsis ; c) slope and upland vegetation dominated by Sphenobaiera, Ginkgoites, Eretmophyllum and Pityophyllum. • The Siberian Middle Jurassic (Aalenian) flora from the Kansk Basin was reviewed. • Macro- and micro-morphological descriptions of each species are provided. • The work complements the species composition of the Rybinsk plant assemblage. • The outcome highlights the identification of three vegetation units and Middle Jurassic Palaeoecosystem. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of modern pollen transport processes is a prerequisite for utilizing fossil pollen to elucidate the evolution of palaeoclimates and palaeoenvironments, especially in areas such as southwestern China where complex mountainous topography results in vegetation heterogeneity. In this paper, we selected four vertical profiles in mountainous regions of southwestern China, each with distinct plant communities, to investigate the relationship between modern pollen rain, vegetation types and vegetation cover, and to quantify the influence of environmental factors. Results show that pollen assemblages are generally representative of regional plant communities, although long-distant transport of arboreal pollen by valley winds can introduce signals from a much wider area. The calibrated arboreal pollen percentage (AP) and ratio of arboreal pollen to non-arboreal pollen (AP/NAP) serves as reliable quantitative proxies for vegetation cover, highlighting the importance of appropriate calibration when interpreting fossil pollen assemblages. Climate is the primary determinant of pollen distribution across these mountains, with mean temperature of the coldest month (MTCM) playing the most prominent contribution. Additionally, the impact of vegetation cover and soil nutrients on pollen distribution are also significant. Our modern study improves the accuracy of pollen interpretation for palaeoenvironmental reconstruction in mountainous regions of southwestern China. • Pollen assemblages can effectively depict the characteristics of mountain vegetation communities. • The calibrated AP percentage and AP/NAP can quantitatively indicate arboreal cover. • MTCM controls pollen distribution in different mountains of southwestern China. • Climate dominates pollen distribution below treeline and vegetation cover controls above treeline. [ABSTRACT FROM AUTHOR]

Widely distributed wetlands in China play an important role in the global carbon cycle. However, the long-term response of wetland evolution and carbon storage in tropical southern China to climate change remains unclear. Here, we present a sediment core record from the Tiaoshu Wetland in the northern Leizhou Peninsula and multiple proxy indicators are investigated, with the aim of better understanding past vegetation and environmental changes. The following conclusions were drawn: (i) The organic matter deposited in the Tiaoshu Wetland was mainly derived from terrestrial C3 plants and aquatic plants growing in and/or around the catchment. The temporal variability in the relative proportions of organic matter contributed by various sources revealed paleoenvironmental changes in the study area, generally consistent with regional and global climate records. (ii) The peat formation pattern in the Tiaoshu Wetland is in contrast to some individual sites reported in subtropical China, suggesting that there may be different peat formation patterns in the tropical and subtropical regions of China, which may be closely related to specific hydrothermal conditions in different regions. In addition, by comparison with atmospheric CH 4 concentrations, our results suggest potential relationships between the evolution of wetlands in tropical China and global atmospheric CH 4 cycles. • Alternation between terrestrial and aquatic plants dominated the organic matter sources in the Tiaoshu Wetland. • Variations in organic matter sources reveal vegetation succession and a response to climate changes. • Peat formation patterns may differ between tropical and subtropical regions of China. [ABSTRACT FROM AUTHOR]

Massive dome-shaped coral Porites are the predominant choice for paleoclimate studies due to their consistent and reliable growth. When growing close to sea level, they become limited in their vertical growth and form so-called 'microatolls'. Microatolls have not yet been extensively explored for paleoclimate reconstruction. Here, we investigate how reliable modern Porites microatolls are against empirical sea-surface temperature using Sr/Ca, δ18O, Li/Mg and Sr U paleothermometry methods on samples from the Society Islands, French Polynesia. Our results show Sr/Ca ratios have the lowest Standard Error of the Inverse Prediction (SEIP) at 0.415 °C (N = 41) with a calibration of Sr/Ca (mmol mol−1) = −0.082 ± 0.006 SST (°C) + 11.256 ± 0.170 and with high reproducibility across multiple corals. The reproducibility of δ18O was less good, with SEIP increasing to 0.829 °C (N = 41). Considering methods directly from the literature, Li/Mg ratio empirically corrected for Sr/Ca had the best balance between bias and precision where no local calibration could be available. This study independently evaluates and confirms the suitability of Porites microatolls from well-flushed environments for paleoclimate studies. Fossil dome-shaped Porites grow anywhere between near-surface and roughly 20 m depths which inherently incorporates uncertainty into any sea surface temperature reconstruction. This uncertainty is significantly reduced for microatolls due to their well-constrained bathymetry. The study represents a fundamental step in paleoclimate research targeting consistently near the water-air interface bringing reliability and, especially when combined with their ability to reconstruct past sea-level changes, microatolls have the potential to be central for future paleoenvironmental studies. • Investigation into the potential of Porites microatolls for SST reconstruction. • Comparison between recent and more conventional coral paleoclimatology methods. • Application of Sr U and Li/Mg paleothermometer. • Accuracy and reproducibility of Sr/Ca proved to be the most suitable proxy for SST reconstruction. [ABSTRACT FROM AUTHOR]

Antarctic fjords and coastal bays are excellent traps for sediment and represent key areas for high-resolution investigation of past environmental conditions. Robertson Bay is an understudied coastal area located at the confluence of the Ross Sea and the Southern Ocean. Recently obtained seafloor morphology data indicate the presence of a cross-shelf elongated valley, composed of three minor basins separated by sills and seabed ridges with an arcuate shape. Several cores were collected within the basins, and investigated using a multiproxy approach including sedimentological, chemical, geochemical, and micropaleontological characterization to reconstruct the paleoenvironmental evolution from the last glacial period to present. The ages of two of these cores are constrained using ramped pyrolysis oxidation radiocarbon dating. Four sedimentary facies were recognised from which we developed a sedimentary model covering the last 21,000 years (21 ka BP). Our record provide evidence for a covering ice shelf cover from 21 to 16.5 ka BP, which gradually receded between 16,5 and 11 ka BP due to the progressive intrusion of modified Circumpolar Deep Water, thereby promoting the formation of Ice Shelf Water and High Salinity Shelf Water. From 11 to 5,8 ka BP, the ice shelf continued shrinking and nutrient-rich of modified Circumpolar Deep Water penetration onto the continental shelf progressively favoured diatom blooms and a general increase in primary productivity until 5.8 ka BP. The Late Holocene is characterised by an alternation of prolonged sea ice cover with stratified water column and strong bottom current with prolonged sea-ice free season with the intrusion of modified Circumpolar Deep Water and very slow energy bottom current. • First paleoenvironmental study from the LGM to the present in Robertson Bay. • Strong impact of regional ice sheet recession on environmental conditions and productivity. • Multiproxy approach constrained by Ramped Pyrolysis based age model. • The coastal bay area was studied by sediment cores and geophysical data. [ABSTRACT FROM AUTHOR]

The recent geological history of the Northern Andes is characterized by the interaction of dynamic surface processes such as volcanic activity, fluvial erosion, mass movements, etc. that have shaped landscapes for millennia. Despite its great geological and biological importance, the long-term ecological history of middle-elevation tropical habitats (between 1000 and 2500 m.a.s.l.) is unknown, due to the scarcity of suitable paleo archives preserving the paleoecological signal, leading to a critical data gap. This manuscript reports well-preserved subfossil woods of the Pleistocene volcanoclastic deposits from the Central Cordillera of Colombia. Four wood specimens are described and identified as Terminalioxylon gumminae sp.nov., Andesanthus risaraldense sp.nov., Anacardium quindiuense sp.nov., and Chrysochlamys colombiana. This report demonstrates the potential of volcanic deposits in the Northern Andes as paleo archives, and contributes to the fossil record of the tropical Andes, as it contains elements of mid-altitude vegetation preserved in association with the Pleistocene volcanic activity of the Central Cordillera. The environments where these subfossil species lived resemble present environmental conditions. This is a baseline for future paleobotanical exploration and paleoenvironmental analyses. • We investigated four subfossil woods from the late Pleistocene of the Northern Andes. • Novel species of Anacardium, Andesanthus, and Terminalioxylon described. • One specimen was identified as Chrysochlamys colombiana. • This is a baseline for future paleobotanical and paleoenvironmental studies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sterol geochemical features depend on lake natural processes and anthropogenic perturbations. • Cholesterol and total C 27 sterols are enriched in the sediments of deep lakes. • Sitosterol and total C 29 sterols are enriched in the sediments of shallow lakes. • Alpine lakes are characterized by an extreme dominance of sitosterol. • Cholesterol/brassicasterol ratio can be used to reconstruct historical lake nutrient changes. Sterol-based geochemical proxies are used to reconstruct the historical environmental evolution of lakes and their catchment areas. However, the reliability of these proxies remains challenging because the link between environmental drivers and sterol geochemical characteristics has not been fully assessed. In this study, the abundance and composition of sterols were determined in sediment cores from nine lakes with contrasting natural conditions and anthropogenic perturbations to establish the response pattern of sterol geochemical characteristics to environmental drivers, and the controlling mechanisms behind this phenomenon were also tentatively speculated. Our results revealed that cholesterol and total C 27 sterols were consistently enriched in the sediment cores from deep lakes (Fuxian, Lugu, and Erhai). In contrast, sitosterol and total C 29 sterols were consistently enriched in the sediment cores from shallow (Changdang, Taibai, Chaohu, and Liangzi) and alpine lakes (Heihai and Jiren). The variable sterol distribution can be attributed to different natural processes in these lakes. In deep lakes, the productive zooplankton, owing to the long water column, contributed to high cholesterol levels; in shallow lakes, the delivery of massive terrestrial organic matter through abundant inflowing rivers caused a large sitosterol influx. In alpine lakes, the rapid input of alpine meadows due to the dense growth of these plants on lake shores and adjacent areas resulted in the dominance of sitosterol. The significant influence of natural processes on sterol geochemical characteristics stated above implies that the lake natural background should be considered when sterol proxies were used in paleoenvironmental studies. Comparison of sterol ratios in sediments deposited in the oligotrophic and eutrophic phases of each lake revealed a marked influence of anthropogenic perturbations on sterol distribution. In particular, the cholesterol/brassicasterol ratio exhibited consistent and significant variation with nutrient enrichment in shallow or alpine lakes, but not in deep lakes, revealing the possibility of using this ratio as a nutrient indicator in the former two types of lakes. [ABSTRACT FROM AUTHOR]

The Cuvieri Cave was the subject of numerous paleoenvironmental and paleontological studies, but none of them highlighted the fossil and subfossil remains of Anura. This work reports the occurrence of bone parts of anurans from the Holocene. The recovered material consists of axial and appendicular bones of different sizes and proportions, suggesting the presence of different species. The specimens were observed in two periods, the oldest occurring in the PleistoceneHolocene boundary and the vast majority in layers with ages below 6 thousand years BP. The period of absence from the record coincides with the period known as the Archaic Gap in which there was low or no human occupation in Lagoa Santa. [ABSTRACT FROM AUTHOR]

The late Carboniferous–early Permian represents a key period in the Phanerozoic history, given the major global geodynamic and climate modifications. The aim of this work is to better understand the context and characteristics of the sedimentation recorded in the continental environments of eastern equatorial Pangea at this time, through the example of the Autun Basin (northeastern Massif Central, France). The Autun Basin contains the historical stratotype of the Autunian continental stage, and its stratigraphy was recently improved by accurate numerical ages. This basin formed in an extensional tectonic context during the latest stages of the Variscan orogeny, and it is essential to study its paleoenvironmental evolution to provide new insights into the sedimentary evolution of contemporaneous surrounding basins. Using field and subsurface data, we propose a refined sedimentological model for the Autun Basin, relying on updated facies interpretations, organic matter content fluctuations, and sequence stratigraphy concepts and correlations. The continental environments of the lower sedimentary succession of the Autun Basin, previously considered to be fluvial and lacustrine, are herein re-interpreted as mainly lacustrine, comprising fine-grained organic matter-rich deposits, and supplied by coarser-grained deltaic siliciclastic sediments, without preservation of strict fluvial sedimentation. The determination of the sequence stratigraphy cycles, strengthened by the quantification of the organic matter content, and reflected by the temporal succession of progradational and retrogradational trends, is used to determine new correlations between several sections, as well as to reconstruct the paleoenvironment evolution at the Carboniferous–Permian transition. This study provides evidence that the sedimentation area of the Autun Basin at the time of its filling was much larger than the preserved basin area, and suggests connections with contemporaneous neighboring French basins, pointing to a large sedimentary system in the northeastern Massif Central area rather than narrow and isolated basins. [ABSTRACT FROM AUTHOR]

Grain size is an important textural property of sediments and is widely used in paleoenvironmental studies as a means to infer changes in the sedimentary environment. However, grain size parameters are not always easy to interpret without a full understanding of the factors that influence grain size. Here, we measure grain size in sediment cores from the Bering slope and the Umnak Plateau, and review the effectiveness of different grain size parameters as proxies for sediment transport, current strength, and primary productivity, during a past warm interval (Marine Isotope Stage 11, 424-374 ka). In general, sediments in the Bering Sea are hemipelagic, making them ideal deposits for paleoenvironmental reconstructions, but there is strong evidence in the grain size distribution for contourite deposits between ~408-400 ka at the slope sites, suggesting a change in bottom current transport at this time. We show that the grain size of coarse (>150 µm) terrigenous sediment can be used effectively as a proxy for ice rafting, although it is not possible to distinguish between iceberg and sea ice rafting processes, based on grain size alone. We find that the mean grain size of bulk sediments can be used to infer changes in productivity on glacial-interglacial timescales, but the size and preservation of diatom valves also exert a control on mean grain size. Lastly, we show that the mean size of sortable silt (10-63 µm) is not a valid proxy for bottom current strength in the Bering Sea, because the input of ice-rafted silt confounds the sortable silt signal. [ABSTRACT FROM AUTHOR]

Hematite is a canted antiferromagnet with reddish color that occurs widely on Earth and Mars. Identification and quantification of hematite is conveniently achieved through its magnetic and color properties. Hematite characteristics and content are indispensable ingredients in studies of the iron cycle, paleoenvironmental evolution, paleogeographic reconstructions, and comparative planetology (e.g., Mars). However, the existing magnetic and color reflectance property framework for hematite is based largely on stoichiometric hematite and tends to neglect the effects of cation substitution, which occurs widely in natural hematite and influences the physical properties of hematite. Thus, magnetic parameters for stoichiometric hematite are insufficient for complete analysis of many natural hematite occurrences and can lead to ambiguous geological interpretations. Remagnetization, which occurs pervasively in red beds, is another ticklish problem involving hematite. Understanding red bed remagnetization requires investigation of hematite's formation and remanence recording mechanisms. We elaborate on the influence of cation substitution on the magnetic and color spectral properties of hematite, and on identifying hematite and quantifying its content in soils and sediments. Studies of remagnetization mechanisms are discussed, and we summarize methods to discriminate between primary and secondary remanences carried by hematite in natural samples to aid primary remanence extraction in partially remagnetized red beds. Although there remain unknown properties and unresolved issues that require future work, recognition of the properties of cation-substituted hematite and remagnetization mechanisms for hematite will aid identification and interpretation of the magnetic signals that it carries, which is environmentally important and responsible for magnetic signals on Earth and Mars. [ABSTRACT FROM AUTHOR]

Branched glycerol dialkyl glycerol tetraethers (brGDGTs), special membrane-spanning lipids derived from some bacteria, are widely used as molecular tools in paleoenvironmental studies to reconstruct terrestrial temperature and pH conditions. However, the impact of microtopography discrepancies on the accuracy and applicability of brGDGT-based proxies remains unclear. Here we investigated the distributional patterns of brGDGTs and bacterial communities within the hummock-hollow microtopography in the mid-southern Tibetan peatlands. Our results show that the methylation index of C5-methyl brGDGTs (MBT′ 5ME) values are significantly correlated with the local mean annual air temperature (MAAT). However, the peat-specific temperature calibration exhibits an underestimation of MAAT peat compared to the present MAAT. We find the MBT′ 5ME values are significantly lower in the moist hollows than that in the drier hummocks. This discrepancy could be primarily attributed to the shifts in bacterial communities and the physiological adaptation of brGDGT-producing bacteria driven by the high soil water content. These findings highlight the remarkable variability of MBT′ 5ME values at small spatial scales, which holds profound implications for paleotemperature reconstruction in alpine peatlands. • The abundances of IPLs and CLs, particularly CL-IIIa, are higher in the moist hollows than in drier hummocks. • The relative abundance of anaerobic bacteria increases in the hollows compared to hummocks. • The varied soil water content and bacterial characteristics differ the MBT′ 5ME values between the hummocks and hollows. [ABSTRACT FROM AUTHOR]

Previous paleoenvironmental studies have revealed three latitudinally distributed climate zones across East Asia during the Eocene, including a vast humid climate zone in northeast China. However, the formative cause, long-term evolution, and related driving mechanisms of this humid climate remain largely unknown. Here, we reconstruct a long-term, continuous evolutionary history of Eocene hydroclimate and vegetation from the Fushun Basin (northeast China) by analyzing synthesized palynological and lithofacies records. These results reveal three distinct paleoenvironmental intervals with characteristic lithological and palynological features superimposed on a long-term stepwise cooling and drying trend during the Eocene. The interval from the late Paleocene to early Eocene is characterized by coal seams and the dominance of swamps and broadleaved forests, indicative of a warm and humid climate. The middle Eocene (∼46–41.2 Ma) is characterized by oil-shale deposits and a substantial increase in broadleaved forests, associated with a relatively warm and humid climate. The late Eocene (41.2–37.8 Ma) is distinguished by the onset of mudstone–shale cycles and a substantial increase in xerophytic shrubs and coniferous trees, associated with a cooler, drier climate and increased climatic variability. Notably, these phases temporally correlate with three progressively smaller incursions superimposed on a pattern of long-term proto-Paratethys Sea retreat. This finding demonstrates that the stepwise westward retreat of the proto-Paratethys Sea played at least an equally important role as long-term global cooling in regulating hydroclimate changes in mid-latitude Asia. • Eocene palynological and lithofacies records of Fushun Basin were synthesized. • Eocene climate and vegetation changes were divided into three distinct stages. • Northeast China's moisture driven by westerlies modulated by proto-Paratethys Sea. [ABSTRACT FROM AUTHOR]

Palaeosols are common in sedimentary successions of continental origin, and notably they comprise the majority of the thickness of some accumulated successions of fluvial origin. Yet, detailed investigation of palaeosols and evaluation of their palaeoenvironmental significance are not routinely undertaken in detail in many sedimentological studies. A careful analysis of palaeosols may, however, reveal that sedimentary units, which appear similar if based solely on the facies analysis, indeed show strongly distinct palaeoenvironmental and depositional characteristics. This is the case of the upper portion of the Bauru Group, a 100–190 m-thick Maastrichtian red sandstone unit of fluvial origin, present over an area of c. 180,000 km2 in south-eastern Brazil. In this study, the palaeosols of this unit, which constitute 25–92 % of the succession by thickness, are used to decipher palaeoenvironmental climate conditions, sediment source areas, and relationships between pedogenic and depositional processes. Through the combined study of macroscopic, micromorphological, and geochemical aspects of the palaeosols and of facies analysis of the deposits, the upper portion of the Bauru Group succession is separated into three sectors: north-western, north-eastern, and south-eastern. Although these three areas are all characterised by similar lithology types and lithofacies, indicative of deposition in alluvial systems, the palaeosol analysis highlights that they were each characterised by different climate, different clastic source areas and different dynamics and interaction of the pedogenic and sedimentary processes. This research reveals the critical significance of the palaeosols for discriminating otherwise apparently similar depositional units. [Display omitted] • Palaeosols are significant proxies for stratigraphy and palaeoenvironmental studies. • The upper Bauru Group was considered a homogenous depositional system. • Palaeosols demonstrate the upper Bauru Group comprises three depositional systems. • Studies involving continental deposits cannot ignore the analysis of palaeosols. [ABSTRACT FROM AUTHOR]

Fossil shells of the gastropod Gyraulus sp. are widespread in the sediments of wetlands and lakes, and in fluvial and lacustrine depositional sequences on the Tibetan Plateau (TP). Although aragonite shells of Gyraulus sp. are a potentially valuable archive of information on environmental changes, the living environment of Gyraulus sp. and the significance of its shell geochemistry (e.g., Sr/Ca s , Mg/Ca s , δ13C s, δ18O s) are unknown or disputed. In this study we investigated living specimens of the dominant species of Gyraulus sp. (Gyraulus convexiusculus) in rivers, wetlands, and lakes on the TP, together with its fossil shells in the Holocene lacustrine sediments of Nam Co (NC) on the TP. Specifically, we measured the values of Sr/Ca s , Mg/Ca s , δ13C s, and δ18O s of the modern and fossil shells. Our results indicate that the hydrochemical composition and electrical conductivity of the ambient water significantly affect the survival and abundance of G. convexiusculus. The environmental tolerance of G. convexiusculus can be ordered as: carbonate-type > sulfate-type > chloride-type. Additionally, we speculate that the upper threshold of electrical conductivity for the survival of G. convexiusculus does not exceed ∼4544 μS/cm. Furthermore, we established the relationship between modern G. convexiusculus shells and its host water and developed Gyraulus -based transfer functions (TFs). To assess their potential for paleoenvironment reconstruction, the TFs were then applied to fossil shells of G. convexiusculus collected from a Holocene lake sediment profile from a terrace around NC. We show that Sr/Ca s in G. convexiusculus is a potentially reliable proxy for reconstructing the Sr/Ca of the paleo-water (Sr/Ca Paleo-w) and the paleoconductivity. By contrast, Mg/Ca s in G. convexiusculus cannot be used for environmental reconstruction. δ13C s in G. convexiusculus primarily reflects the δ13C DIC of the host water. When the host water is deficient in HCO 3 − + CO 3 2− (<280 mg/L) there is an increased supply of dissolved carbon derived from organic sources to the shells of G. convexiusculus. Overall, δ18O s in G. convexiusculus is likely one of the most reliable indicators for the δ18O w of the host water of the lakes on the TP. • Hydrochemical composition of ambient water influences distribution of Gyraulus sp. • Sr/Ca s of G. convexiusculus is a valuable proxy for paleoenvironmental studies. • Mg/Ca s of G. convexiusculus cannot be used for paleoenvironmental studies. • δ13C s of G. convexiusculus depends on the δ13C DIC of the host water. • G. convexiusculus is one of the most reliable archive of δ18O w. [ABSTRACT FROM AUTHOR]

The Jurassic Da'anzhai Member in the Sichuan Basin is a stratigraphic unit characterized by widespread mudstone and hybrid sedimentation. It comprises various lithofacies types and sedimentary structures, including massive structure, laminated structure, mud rip-up clasts and erosion surfaces. By means of detailed analysis of core, logging, thin sections, scanning electron microscope, XRD and XRF data, six lithofacies types are identified in the Da'anzhai Member, and the genetic mechanisms of these lithofacies such as sandy debris flow, turbidity current, bioclastic flow and still water sedimentation are analyzed based on the characteristics of lithofacies. A complete third-order cycle was identified in the LA 1 and RA 1 well based on the variation in the value of gamma ray, bioclastic content as well as lithofacies characteristics. The paleo-sedimentary environment of Da'anzhai Member of Sichuan Basin is reconstructed on the basis of geochemical proxies such as Sr/Cu, Ca/(Ca + Fe), V/(V + Ni), V/Cr, Ti, Al, Al/(Al + Fe) and Fe/Mn. Different sedimentary environments in the Da'anzhai Member controlled the characteristics of lithofacies distribution and the lake level (water depth) primarily controlled the scale and frequency of the development of hybrid sedimentation and mudstone. During the early and late sedimentary periods of the Da'anzhai Member, the climate was arid, water salinity was high, reducing conditions were weak, and the water body was deep. Sediments such as sandy and bioclastic materials in shallow areas were transported to deeper areas through gravity flows under the influence of sudden events like earthquakes, floods or storms and interbedded with still water mudstones. In the middle period of the Da'anzhai Member, the climate was humid, water salinity was low, reducing conditions were strong, and the water body remained deep. A large amount of deep-water mudstone developed in this period, with gravity flow deposits appearing as thin layers. Finally, the comprehensive sedimentary model of the study area is completed based on this characteristics. • Six lithofacies types were identified based on a petrological characterization study. • Lithofacies characteristics were analyzed, identifying sedimentary processes: gravity and still water depositions. • Paleoenvironmental reconstruction of the Da'anzhai Member was performed , analyzing its influences on sedimentary characteristics and lithofacies distribution. • Sedimentary model of Da'anzhai Member was established from petrological, genesis, and paleoenvironmental studies. [ABSTRACT FROM AUTHOR]

This article discusses recent developments in the field of speleothem paleoclimate and paleoenvironmental science. Speleothems, such as stalagmites and stalactites, have been used to reconstruct past climate and environmental conditions using methods like U-Th absolute dating and stable isotope analysis. The article highlights the use of new techniques, such as U-Pb dating and the analysis of trace elements, clumped isotopes, and fluid inclusions, to extend the time range of speleothem-based paleoclimate reconstructions. The special issue includes a range of studies from different regions and time periods, covering topics such as hydroclimate variability, stalagmite formations, rainfall dynamics, and Holocene climate features. Additionally, the article introduces a web-based tool called the SISAL webApp, which aims to increase accessibility to the Speleothem Isotope Synthesis and AnaLysis (SISAL) database. Overall, these studies contribute to a comprehensive understanding of past climate variations. [Extracted from the article]

The present paper outlines the results of a detailed study of calcareous nannofossils and small foraminifera made on Campanian marine deposits from the southwestern part of the Transylvanian Basin, Romania, part of the marine-to-continental transitional Petrești succession that yielded the oldest temporally well-constrained continental vertebrate remains in this area. These results are integrated with new and previously published palynostratigraphic information as well as with novel detrital zircon geochronometry data. All three groups of fossils (calcareous nannofossils, small foraminifera, and palynomorphs) convergently indicate an early to middle Late Campanian age for the marine part of the Petrești section. Based on detrital zircon analyses, the most likely maximum depositional age of the studied deposits is 76 ± 1.7 Ma, thus confirming the age supported by microfossil assemblages. Palaeoenvironmental interpretation of the fossil assemblages recovered from the marine part of the Petrești section suggests that despite their flysch-like facies, these beds were deposited in a continental shelf setting, under suboxic conditions and frequent fluctuations in nutrient supply to the seafloor, but quite stable environmental conditions within the water column. The synthesis of all currently available biostratigraphic and geochronologic data from the Petrești succession suggests a middle-late Late Campanian start for the expansion of the emergent land areas that made up the latest Cretaceous Hațeg Island, earlier than previously accepted dates (Maastrichtian) for this event. Furthermore, it documents the establishment of a diversified continental vertebrate faunal assemblage by the second half of the Late Campanian on these emergent lands while also providing further evidence for a later, post-Campanian arrival of certain iconic Hațeg Island dinosaur groups such as titanosaurs and hadrosauroids. Finally, our data show that kogaionid multituberculate mammals were already members of the earliest known Hațeg Island faunas, extending the fossil record of this group from the Maastrichtian into the later part of the middle Late Campanian. • Integrated study of a key Upper Cretaceous succession in Transylvania, Romania. • It hosts a rare instance of continuous end-Cretaceous marine-continental transition. • Both biostratigraphy and geochronometry restricts marine beds to the Upper Campanian. • Continental vertebrate remains occur within the upper part of the local succession. • Oldest well-constrained occurrence of these vertebrates in the marine Upper Campanian. [ABSTRACT FROM AUTHOR]

One of the key areas and periods for dinosaur evolution is considered to be Early Cretaceous East Asia, of which paleoclimate, that affected dinosaur diversity, needs to be accurately estimated. This study reconstructed paleoenvironmental information from two paleosol sections of the Lower Cretaceous Tetori Group in Hokuriku province, Japan. Elemental and isotopic compositions indicate that the two sections (Sections K5 and T1) formed under similar mean annual temperature (MAT) and mean annual precipitation (MAP) but exhibit significantly different paleosol colors (red in the Section K5, and gray in the Section T1) and mineralogy of carbonate nodules (dolomite–siderite in the Section K5, and dolomite–calcite in the Section T1). In addition, the oxygen isotopic ratio of carbonate minerals in the Section K5 was significantly low. The differences in sedimentary features and isotopic composition were considered to reflect the differences of seasonal climatic factors (e.g., monsoon) and local settings (e.g., drainage condition) despite the two sections exhibiting similar MAT and MAP. The results of this study suggest that the northeastern margin of East Asia, where the Tetori Group was deposited, had temperate and humid climate with monsoonal contrast in humidity during Aptian to Albian. [ABSTRACT FROM AUTHOR]