bluuebunny/crossref_metadata_2025 huggingface dataset:
High-P metamorphism in the Mesoproterozoic: Petrochronological insights from the Grenville Province
Authors: Lotout Caroline , Indares Aphrodite , Vervoort Jeffrey , Deloule Etienne
Published: March 2024

In the Grenville Province, high-P rocks that are discontinuously exposed along the margin of the allochthonous belt preserve the record of deep crustal processes and are an essential puzzle piece to understanding Mesoproterozoic geodynamics. The Manicouagan Imbricate zone (MIZ) is one of the three high-P domains from the Grenville Province. It is located in the Central Grenville between the Parautochthonous Belt to the North and the orogenic hinterland to the South, that were metamorphosed during the 1005–980 Ma Rigolet and 1080–1020 Ma Ottawan orogenic phases, respectively. In the western MIZ, the Lelukuau Terrane (LT) mostly consists of Labradorian-age (~1650 Ma) mafic suites with a fringe of aluminous rocks at its southern edge. Metamafic samples from the Western and Eastern parts of the MIZ display a peak assemblage of garnet, clinopyroxene, plagioclase, rare pargasite or edenite, and quartz ± kyanite. Pseudosection modelling suggests high-P granulite peak conditions at ca. 14 to 16 kbar and 800–900°C, with the scarcity of hydrous phases and quartz explaining the lack of evidence for partial melting. Zircon cores from the Western LT sample show a maximum magmatic age of ca 1.6 Ga. Lu–Hf and Sm–Nd dating on garnet from this sample yield ages of 1020 ± 7 Ma and 1005 ± 13 Ma, respectively, overlapping within error and inferred to represent peak metamorphic conditions followed by fast cooling. In the Eastern LT sample, garnet Lu–Hf dating yields two ages that are consistent with a petrographically preserved two stage growth, at 1033 ± 6 Ma and 1013 ± 6 Ma, while the Sm–Nd age indicates cooling at 1003 ± 8 Ma. The recorded high-P granulite facies conditions highlight a late Ottawan to Rigolet-age localized crustal thickening at the margin of the hinterland during the propagation of the orogen to the NW, with a possible younging of the high-P granulite-facies metamorphism from the Eastern to Western LT. These new results indicate that the high-P belt in the Central Grenville does not represent the exhumed base of an Ottawan age orogenic plateau, as previously proposed, and that no tectonic hiatus exists between the two orogenic phases, as generally thought. Finally, this publication highlights the diversity and diachronicity of the high-P domains in the Grenville Province.
REMINDNET- A network for the Recovery of Mining District
Authors: Šancer Jindřich , Möellerherm Stefan , Kluzová Eva , Mužák Jiří , Karu Veiko , Fociro Ana , Adjijski Vancho , Dogan Tansel , Schwendner Peter
Published: March 2024

The extraction of minerals and metals from the earth's crust is as old as human mankind. The management of mine closure as well as post-closure is getting more and more attention, because in Europe as well as worldwide former mining regions are affected by environmental residues such as tailings, waste dumps, subsidence, and contaminated water, which are the results of unsatisfactory environmental performance of the mining industry in the past. All European countries face these problems and many of them lack the funds as well as capacity to manage these former mining sites. This network of proposers with 74 scientists and practitioners from more than 50 organisations from 32 EU countries focus on legislation, governance and management of these legacies, financing, and rehabilitation and monitoring techniques to improve implementation to minimize post-closure mining legacies. The project is organised into five work packages: government and management practices; socio-economic aspects and financing; environmental monitoring and risk management and use of abandoned mines; training and capacity building; dissemination, communication, and project management. The project will establish an European mining legacy database, compare present legal framework, governance structures and management approaches, provide input to mine authorities, regulators and financial institutions on socially balanced and environmentally friendly management of mine legacies, harmonise best practices, standards and lessons learnt for comprehensive and sustainable management of raw materials extraction legacies and disseminate the results to the public through an open access visualization platform. The network pools experts from currently separated fields (e.g. geologists, engineers, environmental and social scientists, metallurgists, economists, legal representatives, etc.) and aims to consolidate knowledge and foster mutual knowledge exchange between researchers.
Observational Study of Valley Breezes in Heterogeneous Terrain: Vertical and horizontal characterization in the Aure Valley (Pyrenees)
Authors: Ortiz-Corral Pablo , Román-Cascón Carlos , Yagüe Carlos , Jiménez-Rincón Juan Alberto , Sastre Mariano , Vegas-Cañas Cristina , Jomé Mathilde , Lohou Fabienne , Lothon Marie , Sun Jielun
Published: March 2024

This research focuses on the observational analysis of the nocturnal downvalley flows within a valley in southern France, near Pyrenees.  Three meteorological stations strategically positioned throughout the valley were installed at different locations within the frame of the LATMOS-i* and WINDABL** projects and in collaboration with the french project MOSAI***. In addition to the measurements near the surface, several radiosoundings were launched during the nights with downvalley flow in order to characterize the vertical structure of these winds. Near the surface, nights with downvalley are characterized by southerly (from the Pyrenees) and progressively increasing winds that produce higher values of turbulent parameters than those observed during daytime when weak synoptic conditions are present. Moreover, the vertical structure of downvalley flow presents significant variations throughout the night, influenced by a complex interaction between the synoptic conditions and the surface processes. Days characterized by strong synoptic forcing, typically from the west in the study region, completely inhibit the downvalley flow formation. However, on days with even moderate synoptic forcing, the north-south orientation of the valley, coupled with the presence of mountains, seems to act as a shield against synoptic winds, allowing the nocturnal downvalley flow to form inside the valley. An analysis of the atmospheric stability using bulk Richardson number at different layers will also be presented. A key focus is to differentiate those layers with higher static/dynamic stability to discern whether turbulence originates from ground-induced thermal effects or dynamically driven by wind.This study highlights the complexity of observational studies trying to differentiate the factors influencing the nocturnal downvalley flows behavior, emphasizing the need to consider both synoptic conditions and surface processes, including the significant roles played by local topography. 
Connection of the magnetosheath jet-like structures with the foreshock and impact on the magnetopause
Authors: Goncharov Oleksandr , Xirogiannopoulou Niki , Grygorov Kostiantyn , Safrankova Jana , Nemecek Zdenek
Published: March 2024

Plasma structures with enhanced dynamic pressure, density or speed are often observed in Earth’s magnetosheath. These structures, known as jets and fast plasmoids, can be registered in the magnetosheath, downstream of both the quasi-perpendicular and quasi-parallel bow shocks Using measurements by the Magnetospheric Multiscale (MMS) spacecraft, Goncharov et al., (2020) showed similarities in the plasma properties of the jets and fast plasmoids. On the other hand, they pointed out that the different magnetic fields inside the structures suggest that the formation mechanisms are not the same. Hybrid simulations by Preisser et al., (2020) have shown differences in the mechanisms of jet and embedded plasmoid formation. Previous studies established that foreshock structures can be a source of the jets (Raptis et al., 2022). Xirogiannopoulou et al. (2023) found that the subsolar foreshock contains several types of structures with enhanced density or/and magnetic field magnitude, like plasmoids, SLAMS and mixed structures. Following the results of Xirogiannopoulou et al. (2023) and Goncharov et al., (2020), we compare our MMS measurements with THEMIS observations. Based on our comparative analysis, we discuss features of jet-like structures, their properties, occurrence, evolution, relation to the foreshock, and impact on the magnetopause.
Incorporating the acclimation of photosynthesis and leaf respiration in the Noah-MP land surface model: model development and evaluation
Authors: Ren Yanghang , Wang Han , Harrison Sandy , Prentice Colin , Mengoli Giulia , Zhao Long , Yang Kun
Published: March 2024

Leaf photosynthetic and respiratory processes are important for the terrestrial carbon cycle. Leaf physiological traits, such as the maximum carboxylation rate and leaf respiration rate at 25˚C (Vcmax,25, R25), the key parameters affecting photosynthesis and respiration rate, acclimate to environmental changes. However, many land surface models (LSMs) assume a constant R25 and Vcmax,25 by plant functional types (PFTs) due to limited understanding of plant acclimation processes. Here, we incorporated the acclimation of photosynthesis and leaf respiration into a land surface model (Noah MP) using the Eco-Evolutionary Optimality principle (Noah MP-EEO), and evaluated the performances of the EEO and standard schemes to simulate photosynthesis and respiration using global plant trait measurements and data from FLUXNET. We demonstrate that R25 and Vcmax,25 varied temporally and spatially within the same PFT (C.V. >20%). This behaviour is captured by the EEO scheme (R2 =0.69 and 0.62 for temporal and spatial variations) but ignored by the standard scheme. At the FLUXNET sites, the standard scheme underestimates gross primary production (GPP) but this is reduced in the EEO scheme. The EEO scheme explains 66% of the variation of site-annual GPP compared to 55% in the standard scheme. The EEO scheme also simulates the variation of leaf respiration (Rleaves) better than the standard scheme (R2 increases from 0.45 to 0.77). The EEO scheme shows less temperature sensitivity than the standard scheme because of acclimation. This study indicates that adopting EEO approaches that do not require PFT-specific parameters improves carbon cycle predictions and could be used in Earth system models for better understanding the climate-carbon feedback.
The role of parametrized shallow convection in tropical cloud systems
Authors: Savazzi Alessandro , Nuijens Louise , de Rooy Wim , Siebesma Pier
Published: March 2024

In current storm-resolving models, the parameterization of shallow cumulus convection is based on the mass-flux framework, originally tailored for coarse mesh sizes O(10-50km). Recent finer grids present a unique opportunity to study the coupling between clouds, convection, and the large-scale circulations. This finer resolution also prompts a critical inquiry into the role of shallow convection parameterization (SCP). Within the context of EUREC4A-MIP, we use HARMONIE-AROME with a grid spacing of 2.5 km to test the mesoscale cloud sensitivity to SCP. While cloud patterns are discernible at this resolution, individual shallow cumuli may not be fully resolved. Our investigation reveals that mesoscale properties of tropical shallow cumulus fields and associated circulations exhibit a pronounced dependence on sub-grid parametrization, with differences in cloud cover up to 20%. We simulate the period from January 1st to February 28th 2020, and compare three configurations of HARMONIE-AROME: 1) the control with active SCP, 2) UVmix-off without momentum mixing by shallow convection, 3) SCP-off without any mixing by shallow convection. Instead of an incremental effect, our results show that UVmix-off and SCP-off can produce opposite responses in the cloud field. UVmix-off produces large anvils, less precipitation, and a cooler lower-troposphere. In contrast, SCP-off produces many smaller clouds which precipitate more in a warmer lower-troposphere due to a more unstable environment, and the buildup of CAPE and turbulent kinetic energy. Importantly, our results underscore that the removal of SCP (and to a lesser extent, the removal of UV mixing) strengthens mesoscale circulations and augments their coverage through increased wind variance, predominantly at scales larger than 25 km. Stronger resolved vertical motion in SCP-off produces stronger circulations, whereas the altered wind mixing in UVmix-off primarily affects the coverage of circulations. The ability to look at parameterized tendencies provides further insight into where the convection is strengthening or weakening the winds. This nuanced exploration contributes valuable insights into the intricate dynamics of mesoscale cloud systems under varying shallow convective parameterizations.
Implications of tourmaline frictional and rheological experiments on fault strength and sliding stability in southern Tibet
Authors: Li Xinze , Zhou Yongsheng , Cheng Lining , Li Jianfeng
Published: March 2024

A large number of tourmaline fault mirrors are exposed in the north-south normal fault system in the southern part of the Tibetan Plateau. Microstructure analysis shows that the tourmaline fault mirror has the characteristics of co-seismic high speed friction sliding and high temperature plastic rheology. In order to reveal the mechanical process of friction-rheological strength and co-seismic slip of tourmaline fault, the frictional and rheological experiments were carried out on the gas-medium triaxial high temperature and high pressure experimental system using undeformed tourmaline in southern Tibet to determine the formation conditions of tourmaline fault mirror. The effective normal stress of frictional experiments is 100Mpa.The pore water pressure is 30MPa. The temperature is 25-500℃, and the shear slip rate is switched between 1μm·s-1, 0.2μm·s-1, 0.04μm·s-1. The experimental results show that stick-slip occurs at 200-350℃, and the speed weakens at 400℃ and 500℃. The rheological experiment temperature is 850-950℃. The pressure is 300MPa, and the strain rate is switched between 2*10-5s-1, 1*10-5s-1, 5*10-6s-1, 7.5*10-6s-1. The experimental results show that the natural tourmaline sample is mainly fractured flow under the experimental conditions. The strength of hot-pressed dry tourmaline sample decreases with increasing temperature. The rheological strength of water samples synthesized by hot pressing was significantly reduced.
Influence of aerosol deposition on snowpack evolution in simulations with the ORCHIDEE land surface model 
Authors: Krishnakumar Sujith , Albani Samuel , Ménégoz Martin , Ottlé Catherine , Balkanski Yves
Published: March 2024

Simulating seasonal snow with state-of-the-art global general circulation models (GCMs) is still challenging. Snow provides fresh water to billions of people and plays an important role in the energy budget of the earth through albedo, which affects not only local but also remote and global climate/hydrological patterns. Therefore, changes in snow amount and length of the season are crucial when investigating climate variability.  One key aspect often overlooked in GCMs is the inclusion of Light Absorbing Particles (LAPs) in snow simulations. LAPs dramatically reduce snow albedo, particularly for visible solar radiation, leading to considerable implications for climate modeling. The intention is to lay the foundations for addressing the issues across different climate conditions through simulations, by adding the snow darkening effect to a multilayered intermediate complexity scheme within ORCHIDEE, the land surface model embedded in the IPSL Earth System Model.LAPs are commonly deposited on the surface of fresh snow and progressively become embedded into deeper layers of the snowpack.  The LAP species taken into account include four log-normal modes of dust, soot, and organic carbons. These tracers allow for the movement of LAPs through different layers of the snowpack, adjusting with snow accumulation or melting. In order to simulate the movement of LAPs, ORCHIDEE has been enhanced with a tracer flow mechanism that carry LAPs from the top snow layer following deposition and move through various layers as snow thickens or flushes with meltwater flow. Our approach to snow albedo deviates from the default method in ORCHIDEE as a function of snow aging through an exponential decay function with dependence on the degree of water saturation and the occurrence of fresh snow deposition. Instead, it integrates the Warren and Wiscombe snow radiative transfer scheme with Kokhanovsky's single scatter properties of snow crystals and the optical properties of LAPs to compute the albedo of impure snow. This study conducted site-level offline ORCHIDEE simulations using observed atmospheric conditions and MERRA2 aerosol deposition data. The integration of LAPs and related processes has led to improved simulations of seasonal snow, achieving more realistic representations of snow albedo compared to pure snow. Our results also show that LAPs play an important role in determining the local snow season length.
Identifying global biases in hydro-hazard research by mining the scientific literature
Authors: Stein Lina , Mukkavilli S. Karthik , Pfitzmann Birgit M. , Staar Peter W. J. , Ozturk Ugur , Berrospi Cesar , Brunschwiler Thomas , Wagener Thorsten
Published: March 2024

Floods, droughts, and rainfall-induced landslides are hydro-geomorphic hazards that affect millions of people every year. These hazards are therefore heavily researched topics with several hundred thousand articles published. The large number of published articles means identifying existing gaps is a challenge, especially regarding research specific to local risk conditions and impacts. How well does hydro-geomorphic hazard research cover heavily impacted regions, different hydro-climatic processes, or relevant socio-economic aspects? In this work, we use natural language processing to search a database of 100 million abstracts for mentions of floods, droughts, and landslides. We annotate all hazards and location mentions and geolocate each study via Nominatim. We use this information to create global gridded research densities for the three hazards based on all study locations from 293,156 abstracts. We then compare research density to environmental, socio-economic, and disaster impact data. The global distribution of research is heavily influenced by human activity, national wealth, data availability, and population distribution. Countries that have been heavily impacted by hydro-geomorphic hazards in the past have a higher research density. However, this relationship strongly depends on country wealth. In low-income countries 100 times more people need to be affected before a comparable research density to high-income countries is reached. This disparity needs to be addressed to reduce disaster impact and adapt to changing conditions in the future. We here give guidance for which regions and hydro-climatic conditions an increased research focus on hydro-geomorphic hazards is most urgent.
Assessment of turbulent dispersion in the Red River plume region, northeast Vietnam, based on Lagrangian observations and modeling
Authors: Sentchev Alexei , Nguyen Duc Thinh , Vu Duy Vinh , Berti Stefano
Published: March 2024

The study aims to assess turbulent dispersion processes in the coastal regions of northeastern Vietnam, in order to meet the major challenge of monitoring the fate of particulate materials in this part of the East Vietnam Sea, home to the most famous tourist sites and economic sites. The study area is strongly influenced by the freshwater discharge of the Red River, which creates a large river plume, greatly affecting coastal circulation and turbulent dispersion. The monsoon wind profoundly alters the dynamics of the river plume, pushing light surface water seaward over long distances, in summer, and toward the coast, in winter. Sea surveys were organized for the first time in this region in 2022 and 2023 to better characterize the processes controlling coastal flow variability and turbulent dispersion in the plume region and surrounding waters. Surface drifters, released in the  plume region, were tracked during short periods of time, lfrom one to a few days. Current velocity profiling and CTD profiling have been also done. Estimates of the relative dispersion based on surface drifter measurements have revealed that the dispersion regime is local, mainly ballistic and Richardson, induced by turbulent eddies whose size does not exceed a few km. Local wind variability, combined with variations in bathymetry, considerably affects the transport pathways of real drifters and modifies the dispersion regime. A coastal circulation model was used to better assess dispersion processes over the entire study area and for a wide range of variability in the main forcing terms. Virtual surface drifters were tracked in the model velocity field during the surveying periods. The results revealed that, on scale of several days, the transport of passive tracers is considerably affected by irregularities in current velocity fields associated with zones of current convergence and divergence. The results also demonstrated that merging observations with model outputs significantly improves the representation of small scale features of current variability, turbulent mixing, and horizontal stirring of tracers in the plume region.
Copernicus POD Service – Impact of High Solar activity on POD
Authors: Lara Espinosa Sonia , Fernández Carlos , Fernández Marc , Peter Heike , Féménias Pierre
Published: March 2024

The Copernicus Precise Orbit Determination (CPOD) Service delivers, as part of the Ground Segment of the Copernicus Sentinel-1, -2, -3, and -6 missions, orbital products and auxiliary data files for their use in the corresponding Payload Data Ground Segment (PDGS) processing chains at ESA and EUMETSAT, and to external users through the newly available Copernicus Data Space Ecosystem (https://dataspace.copernicus.eu/).For the last few years, a progressive degradation of the accuracy of some of the CPOD orbital products has been observed, caused by the increasing solar activity. Solar activity follows an 11-year cycle, and since the minimum in 2020, overall solar activity has been higher and geomagnetic storms have been happening more often. This has two impacts on POD: a more “turbulent” atmosphere which brings higher frequency density changes, making the modelling of the satellite´s drag more challenging, and an increase of ionospheric scintillation, particularly over the polar regions, that causes an increase of the GNSS carrier phase noise.This study aims at characterising better the impact of the solar activity on the different POD products, with a focus on the degradation of orbit determination and predictions required by the Sentinel-1 mission. Overall tendencies since the solar minimum in 2020 are analysed, including a detailed look on strong geomagnetic storms. Mitigation strategies to overcome this situation are evaluated, namely adapting the POD processing dynamic parametrisation, and updating the solar activity proxies (particularly the geomagnetic indexes) more frequently.
Revealing the dominant synoptic effects leading to spring precipitation over the foot and slope of the southeastern Tibetan Plateau
Authors: Wei Peng
Published: March 2024

Spring precipitation over South Asia during 2001 to 2010 was concentrated in the foot and slope of the southeastern Tibetan Plateau with two significant precipitation centers. Rainy day accounted for 99.3% and the average daily precipitation can exceed 11 mm, which was distinct from its surrounding areas. Given the spatial variability of spring precipitation, self-organizing map method (SOM) was firstly applied to cluster the precipitation types, and then the reanalysis product from ERA5 was used to explore the synoptic characteristics of different precipitation types. The results show that the westerly wind-dominated precipitation type occurred 92.2% of the frequency, but the cumulative precipitation only contributed to 73% and the maximum average precipitation was lower than 9.5 mm/day. While other precipitation types were classified to heavy rainfall, which were characterized by the development of a low-level trough, abundant water vapor from the Bay of Bengal, and upward movement. However, the difference of synoptic conditions caused the spatial variability of heavy rainfall: the dynamic-dominated precipitation was distributed at the junction of the Himalayas and the Hengduan Mountains, and the deep boundary layer jet to the north caused strong local convergence and uplift motion, which induced strong precipitation reaching 111.32 mm/day. The moisture-dominated precipitation was close to the northern coastline of the Bay of Bengal far away from the topography, and was feathered by abundant water vapor provided by strong southerly, leading to widespread precipitation up to 79.06 mm/day. We further investigate the reasons for the different circulation conditions. The surface sensible heat provided the necessary conditions for the development of a large-scale low-pressure trough, and apparent heat source generated by heavy precipitation further enhanced the local positive vorticity. This work reveals the dominant synoptic effects leading to spring precipitation over the foot and slope of the southeastern Tibetan Plateau, and deepens the understanding of hydrological cycle in South Asia with the joint influence of complex terrains.
A semi-automatic detection for transient events in northern Apennines using strainmeters and GNSS data
Authors: Tissandier Roxane , Gualandi Adriano , Chiaraluce Lauro , Serpelloni Enrico , Gottlieb Mike , Hanagan Catherine , Marone Chris
Published: March 2024

Low-angle normal faults (i.e. with a dip < 30°) were assumed to have a very low seismic potential (Sibson et al., 1985). However, several observations have shown that earthquakes and aseismic slip can occur along such faults. For instance, the Alto Tiberina Fault (ATF), a 60-km long normal fault with a 15° low angle dip located in the active sector of the Northern Apennines (Italy), is seismically active as well as is actively accommodating part of the Apennines extensional strain. However, the relative contribution of seismic and aseismic slip on it is still unclear. The central and northern Apennines experienced several seismic sequences in the recent decades and a Mw ∼ 4.6 aseismic event accompanied by a seismic swarm of similar or smaller size was also recorded in 2013-2014 along two synthetic and antithetic fault in the hanging-wall of the ATF (Gualandi et al., 2017). The interactions between such minor conjugate faults and the ATF compose a system undergoing complex behavior making the area an ideal candidate to improve our understanding of interactions between different slipping modes. We benefit from data of the Alto Tiberina Near Fault Observatory (TABOO-NFO; Chiaraluce et al., 2014) looking for aseismic events on the ATF and its surrounding faults. The dense network of GNSS, seismometers and borehole strainmeters provides a rarely attained high spatial (inter-distance < 10km) and temporal (from 2009 to nowadays) resolution framework enabling the study of the ATF fault system slip history. We search for transients with a semi-automatic detection tool of slow slip events based on kinematic inversions of strainmeters time series. We also test if these events interact with larger seismic events of the region. We present the strain time series processed with the EarthScope Strain Tools (EarthScope Consortium) and the preliminary signals detected with our tool. The fine analysis of the ATF would help better constraining the behavior of faults and more generally large events. 
Unveiling parental compositions in Andean-type intrusions through magma mingling zones
Authors: Gómez Frutos Daniel , Castro Antonio
Published: March 2024

An important task in petrology is the successful identification of the parental that birthed the magmas constituting the continental crust. Among these, an intermediate parental to subduction related magmas, often referred to as Andean-type, has been determined experimentally in various works. However, identification of a natural rock matching the model compositions has not been accomplished. This difficulty arises primarily from prolonged cooling times, leading to large-scale fractionation and impeding the preservation of the parental magmas. In this regard, quenching becomes a valuable phenomenon, precluding differentiation and thereby preserving the initial compositions. This highlights the relevance of magma mingling zones, a common feature of Andean-type batholiths, as optimal places to probe for parental compositions. Following these considerations, a new set of geochemical analyses from the Gerena magma mingling zone, an Andean-type intrusion in southwest Iberia, is presented to address this problematic. Sampling focused on dark bodies, presumed to be mafic to intermediate in composition. Interestingly, combined evidence from major, trace element and Sr and Sm isotopes suggest that the smaller dark bodies have undergone precluded differentiation. Moreover, according to geochemical modelling their composition can reproduce the neighbouring granites and cumulates through differentiation. These findings emphasize the importance of magma mingling zones as valuable sources of information and shed new light in the identification of the parental composition to Andean-type magmatism.
A novel method for analyzing δ18O by laser ablation IRMS
Authors: Sahlstedt Elina , Loader Neil , Rinne-Garmston Katja
Published: March 2024

Fine-scale variations in the oxygen isotope composition (δ18O) of organic matrices, such as tree rings, provide an important proxy for past environmental conditions. In practice, however, sampling at high resolution is resource intensive and time consuming, requiring the precise cutting, processing, and weighing of sequential samples prior to mass spectrometry. These factors have limited the production of high-resolution δ18O data for research purposes. We have developed a novel method for analyzing δ18O in organic matrices using laser ablation mass spectrometry. This “online” method directly couples a UV laser ablation unit with an isotope ratio mass spectrometer (IRMS). Measurements are conducted on carbon monoxide (CO) gas produced during the laser ablation process. Thus, we sidestep the requirement for separate sample cutting and weighing steps and can take advantage of the high resolution and accurate positioning capabilities of the laser with significantly increased sample throughput and effectively non-destructive sampling. Preliminary results, conducted by analyzing woody materials, indicate a typical measurement precision of ≤0.5 ‰ at spatial resolution of 100µm (spot size). Running a single analysis with the new method takes approximately 15 minutes, which is comparable to a δ18O analysis run by conventional, thermal conversion IRMS. In the future, the new method is expected to provide a valuable tool for investigating fine-scale variation in δ18O in organic matrices.
Downscaling statistical information: a statistical approach
Authors: Benestad Rasmus , Parding Kajsa M. , Mezghani Abdelkader , Dobler Andreas , Landgren Oskar A. , Lutz Julia
Published: March 2024

If the shape of mathematical curves describing local weather statistics are systematically influenced by large-scale conditions and geographical factors, then it may be possible to downscale this kind of information directly. Such curves may include probability density functions (pdfs) for daily temperature/precipitation or intensity-duration-frequency (IDF) curves for estimating return values of intense sub-daily rainfall. Downscaling the shape of such curves may be referred to as ‘downscaling climate’ if we regard ‘local climate’ as the statistical description of various weather parameters. This approach is distinct from the more traditional approach ‘downscaling weather’, where one seeks to estimate particular local states for instance on a day-by-day basis. We present work on downscaling the shapes of pdfs and IDFs involving large multi-model ensembles for the application in climate change adaptation efforts. Our efforts also include an evaluation of both methodology and the global climate models' (GCMs) ability to reproduce observed large-scale climatic variability in terms of the salient spatio-temporal covariance structure. We emphasise that it’s important to combine different strategies for downscaling, e.g. regional climate models (RCMs) and empirical-statistical downscaling (ESD) that are based on different assumptions, for getting robust future regional climate projections.
Deep Circulation in the North Atlantic from Ocean Bottom Seismometer Noise: Insights from the UPFLOW/iReverb Project
Authors: Loureiro Afonso , Tsekhmistrenko Maria , Saoulis Alex , Corela Carlos , Vieira Rui , Reis Jesus , Caldeira Rui , Miranda Miguel , Ferreira Ana
Published: March 2024

Ocean Bottom Seismometers (OBS) face unique challenges in recording seismic events due to their exposure to harsh oceanic conditions. The UPFLOW project deployed 50 OBS of various instrument types in the North Atlantic Ocean. The iReverb project aims to investigate the tidally-modulated current-induced noise generated by water flow around the instrument's frame.This study presents an analysis of seasonal variations in tidal-induced noise on different OBS types across the Azores, Madeira and Canaries region. In some instances, the detected harmonics allow the identification of individual frame components contributing to the noise, offering, on the one hand, insights into potential mitigation solutions for future deployments. On the other hand, our project's main focus - large-scale detection of non-seismic or current-induced reverberation events on OBS - provides valuable data for mapping resonances and tracking ocean currents. Our study uses machine learning/deep learning algorithms, automating the mapping of resonances across large datasets and obtaining a proxy for Ocean Bottom Circulation (OBC) patterns.Here, we present a brief overview of our methodology, describe our results and compare them to classical oceanographic methods to determine ocean currents.This project was funded by the UPFLOW project (ERC grant 101001601), and by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020 (DOI: 10.54499/UIDB/50019/2020), UIDP/50019/2020 (DOI: 10.54499/UIDP/50019/2020) and LA/P/0068/2020 (DOI: 10.54499/LA/P/0068/2020).
Microseismic event analysis using multi-technology sensors at the Quest CCS site
Authors: Goertz-Allmann Bettina Petra , Langet Nadège , Baird Alan , Iranpour Kamran , Kühn Daniela , Vernier Jerome , Rebel Estelle , Oates Steve
Published: March 2024

Microseismic monitoring plays a crucial role in assessing the effectiveness and integrity of Carbon Capture and Storage (CCS) projects. By the detection of microearthquakes we can gain real-time insights into the pressure and stress perturbation due to injection operations, aiding in the detection of potential leakage and ensuring the long-term viability of carbon sequestration efforts.At the Quest CCS site in Alberta, Canada, CO2 injection into a 2 km depth saline reservoir is ongoing since 2015 at a rate of one million tonnes per year.  Several hundreds of small-magnitude seismic events have been located in the Precambrian basement below the reservoir.  A spatio-temporal analysis of seismicity reveals clustered as well as more diffuse distributions of events.  At the Quest site various microseismic monitoring technologies are in place including a downhole 8-level 3-component geophone string, temporary surface nodes arranged in mini-arrays, and downhole optical distributed acoustic sensing (DAS) fiber. The site offers an ideal opportunity to compare and combine the different setups with respect to event detection thresholds and location uncertainties. We demonstrate the importance of advanced signal and array processing techniques and highlight the advantages and disadvantages of different sensor technologies.
Mesozoic tectonic inheritance of the European crystalline basement (SE France) revealed by thermochronology
Authors: Boschetti Louise , Mouthereau Frederic , Schwartz Stephane , Rolland Yann , Bernet Matthias , Balvay Melanie
Published: March 2024

The Alpine orogenic belt in SE France is the result of the collision between the European, Adriatic and Iberian plates. The accreted Variscan continental crust, which now forms the external crystalline massifs (ECMs), recorded a complex Mesozoic thermal and tectonic evolution, that is not fully understood. In the Maures-Tanneron massif (MTM), the basement has undergone periods of subsidence and uplift, the latter indicated by stratigraphic gaps from the Albian and Upper Turonian to the Maastrichian. In the Ecrins-Pelvoux massif (EPM), differential subsidence is documented during Lower Jurassic by lateral variation from marine to continental environment, but most of the Cretaceous and Paleogene periods correspond to a stratigraphic hiatus that ends with the deposition of upper Eocene sediments. The link between these stratigraphic gaps and inheritance associated with the rifting, opening of the Alpine Tethys, and early convergence between Europe, Iberia and Adria is still not resolved. The goal of this study is to elucidate the thermal evolution of the European basement in SE France (EPM and MTM) during the Mesozoic using apatite and zircon fission track low-temperature thermochronology (AFT and ZFT). ZFT data from the southern EPM indicates a complex thermal history with central ages ranging from 158 to 45 Ma, thus revealing significant Jurassic to Eocene resetting and cooling. These ages are interpreted as resulting from several tectonic stages related to (1) Jurassic rifting (2) Mesozoic shortening and erosion and/or (3) incomplete Alpine reset during the main phase of underthrusting below the Penninic Frontal Thrust during the Oligocene. In contrast, the MTM shows several thermal events, comprising a major cooling stage at ca. 200 Ma coincident with the CAMP event preserved in the northern part of the massif. A final cooling event between 30 and 25 Ma, that is mostly represented to the South of the massif, is related to the opening of the Ligurian sea. Intermediate AFT ages between these two events are also identified, likely reflecting cooling events during the Mesozoic that can be resolved using thermal modelling. Finally, the long-term thermal evolution reported from SE France ECMs allows refining the geodynamics of this region from Pangea fragmentation to the onset of Alpine orogeny.
Processes and mechanisms of the initial formation of the Siberian High during the autumn-to-winter transition
Authors: Chen Lingying
Published: March 2024

The Siberian High (SH), an important atmospheric system over Eurasia, exhibits notable seasonality—forming in autumn and peaking in the boreal winter. Many previous studies have revealed the characteristics of the SH in its peak phase; however, the SH formation process remains unclear. This study examined the climatological characteristics of SH formation with a cumulative sea-level-pressure series over the Siberian region based on observational data. First, the SH formation dates were objectively detected in both the climatology (October 1, 55th pentad) and individual years. Then, the thermodynamic processes around SH formation were investigated based on these formation dates. The results indicated that, in the lower troposphere, an anticyclonic circulation dominates over the Eurasian continent after SH formation. In the middle troposphere, an anomalous northeast–southwest-oriented ridge and trough appear over upstream of the SH and the coast of Northeast Asia, respectively. In the upper troposphere, the subtropical westerly jet, with its entrance located over the SH, intensifies and migrates southward, accompanying the amplification of its secondary circulation that features downward (upward) motion over Siberia (south of the Tibetan Plateau). The combined effects of the jet-associated circulation, negative vorticity advection and cold advection associated with the ridge and trough, and diabatic cooling contribute to high-level convergence and large-scale subsidence over the SH area, thereby resulting in SH formation. Further diagnosis reveals that dynamic processes play a more important role in SH formation than the thermal processes do.
Multicomponent Fluid Flow in Deforming and Reacting Porous Rock in the Earth’s crust: hydro-mechanical-chemical model
Authors: Frendak Andrey , Khakimova Lyudmila , Aranovich Leonid , Podladchikov Yury
Published: March 2024

We propose a coupled hydro-mechanical-chemical model and its 1D numerical implementation. We demonstrate its application to the model filtration of a multicomponent fluid in deforming and reacting host rocks, considering changes in the densities, phase proportions, and the chemical compositions of the coexisting phases.The numerical results show the propagation of a porosity wave by means of a viscous (de)compaction mechanism accompanied by the formation of an elongated zone with higher filtration properties. After the formation of such a channel, the formation and propagation of the reaction fronts occurs and are associated with the transformation of the mineral composition of the original rock.
Nature and evolution of the Tethyan Mantle evidenced by the Dras peridotites, Ladakh Himalayas, India.
Authors: Harshe Shivani , Jonnalagadda Mallika , Benoit Mathieu , Duraiswami Raymond , Grégoire Michel , Karmalkar Nitin
Published: March 2024

Prominent exposures of mantle rocks in the form of peridotites are observed extending in the E-W direction having a maximum width of 1.5km at the Dras village, Ladakh, India. The Dras peridotites are mainly dunites bearing chromite mineralization with minor harzburgites and wehrlites. The peridotites are emplaced within the Dras volcanics along with gabbros and radiolarian cherts. They display protogranular textures grading into equigranular mosaic textures typical of mantle peridotites. In dunites, olivines exhibit straight boundaries meeting at 120⁰ indicating recrystallization. Spinels associated with dunites are disseminated as tiny inclusions and at places they are lodged on olivine triple junctions. Porphyroclastic olivine in the harzburgites display kink bands whereas orthopyroxenes (enstatite) in harzburgites are subhedral with exsolution lamellae of clinopyroxene (dioside). Overall textures suggest that the peridotites have undergone progressive deep-seated deformation and solid-state recrystallization. The chromite mineralization associated with dunites displays a variety of structures viz. banded, lenticular, pull-apart, schlieren, massive, disseminated etc. Magnesite veins forming an intricate network in dunites are observed.  Geochemically, the peridotites are relatively fresh (LOI - 0.1 wt % to 5 wt %) with Mg# between 89 and 91, comparable with residual oceanic peridotites. Major element chemistry of the peridotites indicates they are abyssal peridotites, however, depleted REEs, trace elemental concentrations along with enriched LILEs, especially Cs and Nb-Ta and Zr-Hf anomalies indicate formation in a subduction setting. Olivines contain Mg-Cr-rich and Fe-poor rims compared to the cores. Spinels in dunites are chromites with Cr# 68-82 and Mg# 34-48 whereas, in harzburgites, spinels are magnesio-chromites with Cr# 44-55 and Mg# 56-62. Spinel and olivine data suggest that dunites have undergone very high degrees of partial melting about 35% possibly in the supra-subduction zone (SSZ) setting and may have interacted with boninite-like melts.  Harzburgites, on the contrary, are formed by lower degrees of partial melting ranging from 20-25%. However, when remodelled using the clinopyroxene trace element concentrations, the clinopyroxenes from harzburgites suggest 15% to 23% degrees of partial melting. Temperature estimates calculated on select mineral pairs yield temperatures of 816⁰C to 1046⁰C for the peridotites. Distinct petrological and geochemical signatures displayed by the rocks in the present study indicate that the Dras samples show mixed affinities with harzburgites formed at MOR setting whereas dunites being ultra-depleted and refractory owing to higher degrees of partial melting were modified in an SSZ environment.Keywords: Dras, peridotites, mantle, dunite, chromite mineralization, Ladakh.
Characterization and modeling of large-scale aquifer systems under uncertainty: methodology and application to the Po River aquifer system
Authors: Riva Monica , Manzoni Andrea , Sandoval Rafael Leonardo , Porta Giovanni Michele , Guadagnini Alberto
Published: March 2024

Large-scale groundwater flow models are key to enhance our understanding of the potential impacts of climate and anthropogenic factors on water systems. Through these, we can identify significant patterns and processes that most affect water security. In this context, we have developed a comprehensive and robust theoretical framework and operational workflow that can effectively manage complex heterogeneous large-scale groundwater systems. We rely on machine learning techniques to map the spatial distribution of geomaterials within three-dimensional subsurface systems. The groundwater modeling approach encompasses (a) estimation of groundwater recharge and abstractions, as well as (b) appraisal of interactions among subsurface and surface water bodies. We ground our analysis on a unique dataset that encompasses lithostratigraphic data as well as piezometric and water extraction data across the largest aquifer system in Italy (the Po River basin). The quality of our results is assessed against pointwise information and hydrogeological cross-sections which are available within the reconstructed domain. These can be considered as soft information based on expert assessment. As uncertainty quantification is critical for subsurface characterization and assessment of future states of the groundwater system, the proposed methodology is designed to provide a quantitative evaluation of prediction uncertainty at any location of the reconstructed domain. Furthermore, we quantify the relative importance of uncertain model parameters on target model outputs through the implementation of a rigorous Global Sensitivity Analysis. By evaluating the spatial distribution of global sensitivity metrics associated with model parameters, we gain valuable insights into areas where the acquisition of future information could enhance the quality of groundwater flow model parameterization and improve hydraulic head estimates. The comprehensive dataset provided in this study, combined with the reconstruction of the subsurface system properties and piezometric head distribution and with the quantification of the associated uncertainty, can be readily employed in the context of groundwater availability and quality studies associated with the region of interest. The approach and operational workflow are flexible and readily transferable to assist identification of the main dynamics and patterns of large-scale aquifer systems of the kind here analyzed.