bluuebunny/crossref_metadata_2025 huggingface dataset:
The time and geodynamics for the final large-scale lateral accretion of the southern Central Asian Orogenic Belt
Authors: Zhou Hai , Zhao Guochun , Han Yigui , Zhang Donghai , Pei Xianzhi
Published: February 2023

During Carboniferous time, tremendous juvenile arc crust was formed in the southern Central Asian Orogenic Belt (CAOB), although its origin remains unclear. Our work presented zircon U-Pb-Hf and whole-rock geochemical and Sr-Nd isotopic data for a suite of volcanic and pyroclastic rocks from the Khan-Bogd area in southern Mongolia. These Carboniferous pyroclastic rocks generally have some early Paleozoic zircons, probably derived from the granitic and sedimentary rocks of the Lake Zone and the Gobi-Altai Zone to the north, indicative of a continental arc nature. In addition, they have a main zircon U-Pb age of ca. 370–330 Ma, positive Hf and Nd isotopes, and mafic-intermediate arc affinity, similar to the coeval arc magmatism. Moreover, the pyroclastic rocks of the northern area have more mafic and older volcanic components with depositional time (ca. 350–370 Ma; Visean and Bashkirian stages) earlier than that in the southern area (mainly ca. 350–315 Ma; Serpukhovian and Bashkirian stages). Combining a preexisting northward subduction supported by the available magnetotelluric data with a slab rollback model of the main oceanic basin of the Paleo-Asian Ocean (PAO) during Carboniferous and Triassic times, we infer that the Carboniferous arc magmatism was probably derived from a backarc ocean triggered by slab rollback. Thus, the juvenile arc volcanism of Mongolia, together with other areas (e.g., Junggar) in the southern CAOB, represented a significant lateral accretion that terminated after the Carboniferous due to a significant contraction of the PAO. This research was financially supported NSFC Project (42102260, 41890831, 42072267, and 41972229), Hong Kong RGC GRF (17307918), and HKU Internal Grants for Member of Chinese Academy of Sciences (102009906) and for Distinguished Research Achievement Award (102010100).
Resuspension of microplastic particles from arid regions and global impacts on atmospheric concentrations and deposition
Authors: Evangelou Ioanna , Tatsii Daria , Bucci Silvia , Groot Zwaaftink Christine , Stohl Andreas
Published: February 2023

Microplastic particles (MP), i.e., plastic particles with a size between 1 µm and 1 mm, have been detected in all compartments of the Earth system. While we are beginning to develop a quantitative understanding of the primary emissions of MPs such as tire wear, secondary sources from polluted environmental compartments such as the oceans and arid land surfaces, are currently not understood at all.In this study, we use reported MP concentrations in soils across the world combined with MP enrichment ratios (ER) in wind eroded sediments with respect to the soils (Bullard et al., 2021; Rezaei et al., 2019; Tian et al., 2022) and a population density map to estimate MP resuspension factors (RF) from arid regions.  We then use global, 3-hourly dust emissions at  0.5o x 0.5o resolution from FLEXDUST (Groot Zwaaftink et al., 2016, 2017), as a proxy for the spatial and temporal variation of MPs emitted by arid regions. Scaled with the resuspension factors, we estimate the global MP resuspensions. To calculate the uncertainty of our emission model, we conduct a one-thousand-member Monte Carlo simulation with 14 different RF scenarios for each population category, perturbing the MP concentration in soils, the ER and the spatial scale used for the population density.We define, as a reference case, the emissions derived from the average ER, average soil concentrations and 50 km radius population categorization. These MP resuspension emissions are used as input to the Lagrangian atmospheric dispersion model FLEXPART (Pisso et al., 2019; Stohl et al., 2005) to simulate the global atmospheric cycle of resuspended MPs from arid regions. The simulations are driven by ERA5 meteorological fields at 0.5° horizontal resolution and 1-hour temporal resolution.  We simulate the global atmospheric concentration and the deposition of resuspended MPs for different size distributions as well as shapes (spheres, fibers) of MPs. Lastly, we quantify the impact and compare it with observations, to estimate the importance of resuspension from arid regions for global MP abundance.
Stability of organic species in ocean world interiors with geochemical models
Authors: Işık Seda , Daswani Mohit Melwani , Işık Emre
Published: February 2023

The icy moons in the Solar System, such as Europa, Enceladus and Titan, are  of great interest to the astrobiological and biogeochemical communities, owing to their subsurface liquid oceans. These oceans are potential targets for deep explorations of biochemical processes in our cosmic neighbourhood.In our study, we use the Deep Earth Water (DEW) model to calculate the thermodynamic properties of water and aqueous compounds. We employ DEWPython, a modular software interface, enabling access to both DEW and SUPCRT models, with the purpose of investigating the stability of organic molecules in ocean worlds. In particular, we model the equilibrium constant and Gibbs free energy (GFE) as a function of pressure and temperature for reactions involving metabolically essential amino acids, basic molecules possibly involved in the emergence of life (H2, NH3, CH4, etc.), as well as products of water-rock interaction such as serpentinization and abiotic methanogenesis. Considering the results from space missions such as Europa Clipper and Dragonfly, such molecular stability analyses can contribute to the search for conditions ideal for habitability and extraterrestrial life.We map out reaction networks, by first calculating the individual equilibrium constants and GFE changes of the hydrothermal reactions that (i) form a given organic species from inorganics, and then (ii) decompose into other (in)organic molecules. In the final step, we obtain the net equilibrium constant as a measure of the stability of the species, by proportioning the total equilibrium constant of the reactions responsible for the formation of a particular species to those responsible for its destruction. At a given pressure and temperature, a value greater or less than unity indicates that the formation of a species is favourable or unfavourable, respectively.Our current results suggest that alanine and glycine, two common and simple amino acids, can remain stable throughout the ocean columns, and just beneath the seafloors, of Titan and Europa, and thus could potentially be sampled by plumes or cryovolcanism.In the next development phase of our model, we will further constrain the depths at which the species of interest can be found, by identifying and ruling out regions of high pressure ice stability, using the SeaFreeze model.The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). © 2022. Jet Propulsion Laboratory, California Institute of Technology. Government sponsorship acknowledged.Fig 1 : Alanine stability (contours) through Europa’s ocean and ocean floor (colored lines). Positive (negative) regions indicate stable (unstable) conditions.
A global analysis of how human infrastructure squeezes sandy coasts
Authors: Lansu Eva , Reijers Valérie , Höfer Solveig , Luijendijk Arjen , Rietkerk Max , Wassen Martin , Lammerts Evert Jan , van der Heide Tjisse
Published: February 2023

Coastal ecosystems provide vital services, including water storage, carbon sequestration, biodiversity, and coastal protection. Human disturbances, however, cause massive losses. The most direct impact is habitat destruction through infrastructure development, restricting the space available to coastal ecosystems and impeding their capacity to adapt to sea level rise by landward retreat – a phenomenon called ‘coastal squeeze’. While shoreline retreat is intensively studied, coastal congestion through infrastructure remains unquantified. Here we calculated the distance to the nearest human-made structure along 263,900 transects worldwide to show that infrastructure occurs at a 560-meter median distance from the shoreline. Moreover, we find that 18% of global sandy shores harbour less than 100 m of infrastructure-free space, and that 14-17% of the unimpacted space may drown by 2100 according to sea level rise projections. Further analyses show that population density and gross domestic product explain 40-44% of observed squeeze variation, emphasizing the intensifying pressure imposed as countries develop and populations expand. Encouragingly, we find that nature reserves relieve squeezing by 3-5 times, illustrating their effectiveness. Yet, at present only 16% of world’s sandy shores has a protected status. We therefore argue that expansion of nature reserves could be key to preserving coastal resilience to sea level rise.
Simulation of trace gases over the Indian domain: evaluation of the SILAM model
Authors: Sinha Priyanka , Jena Chinmay , Kumar Anikender , Soni Vijay Kumar , Jindal Tanu
Published: February 2023

The global-to-meso-scale dispersion model System for Integrated modeling for atmospheric composition (SILAM) has been implemented over the Indian region for operational air quality forecast. The regional SILAM model generates 96 hours forecasts over a domain at 3kmx3km horizontal resolution. The meteorological forcing is provided from the operational 3 km WRF model. The initial condition is derived from the forecast of the previous cycle of the regional SILAM model and the boundary condition is supplied from the global version of the model. Predicted mixing ratios of trace gases in the atmosphere are compared with the available ground-based observations over the North-Western Indian domain for two consecutive years (2021 and 2022). The paper presents a comprehensive evaluation of SILAM model performance against the observed surface data for trace gases (Surface O3, NO2, and CO). The spatial and temporal variability of trace gases over the domain is well simulated by the model.  The model was also able to catch well the seasonality of trace gases (Surface Ozone, NO2, and CO) over the selected Indian domain. The forecast is found to be very skillful for trace gases and has been helping the air pollution control authorities in India to make informed decisions.
Does the Kutch offshore basin record India's Continental breakup history from Africa to Seychelles?
Authors: Kondepudi Pattabhiram , Pande Kanchan , Munukutla Radhakrishna
Published: February 2023

The breakup of Gondwanaland led to the creation of many rift basins, of which the Kutch basin is one. Previous geochronological studies of the Kutch onshore rocks have established multiple episodes of magmatism ranging from 124-60 Ma. The wells drilled on the Kutch offshore basin also encountered magmatic rocks at various depths, but their temporal relationship is not constrained.                The present study reports the Ar-Ar ages of 5 igneous rocks from the Kutch offshore wells. As determined by petrographical and geochemical analysis, these samples comprise two basalts(b), two dolerites(d), and a rhyolite(r). The plateau ages of the samples are 80.5 ± 0.5(b), 81.4 ± 0.5(r), 100.3 ± 0.6(b), 72.6 ± 0.4(d), and 67.1 ± 0.6(d) (errors quoted at 2σ level). These ages establish magmatism offshore from 100 to 67 Ma. There are several levels where magmatic rocks occur in these wells. Dolerite stringers in Early Cretaceous to middle Jurassic sedimentary rocks have been reported from a few wells.                The geochronology data from the Kutch onshore and adjoining areas in Rajasthan show a magmatic record from 190-60 Ma. There is a possibility that some magmatic rocks in the Kutch offshore basin encountered in different wells may also record the older magmatism and events from the break-up of Gondwana to Seychelles, thereby unfolding the tectono-magmatic history of this region.
Tropical Pacific variability and anthropogenic forcing are the key drivers of the West Antarctic atmospheric circulation variability over the 20th century
Authors: Dalaiden Quentin , Abram Nerilie , Goosse Hugues
Published: February 2023

The future evolution of the West Antarctic Ice Sheet (WAIS) will strongly influence the global sea-level rise in the coming decades. Ice shelf melting in that sector is partly controlled by the low-pressure system located off the West Antarctic coast, namely the Amundsen Sea Low (ASL). When the ASL is deep, an overall increase in ice shelf melting is noticed. Because of the sparse observational network and the strong internal variability, our understanding of the long-term climate changes in the atmospheric circulation is limited, and therefore its impact on ice melting as well. Among all the processes involved in the West Antarctic climate variability, an increasing number of studies have pointed out the strong impact of the climate in the tropical Pacific. However, most of those studies focus on the past decades, which prevents the analysis of the role of the multi-decadal tropical variability on the West Antarctic climate. Here, we combine annually-resolved paleoclimate records, in particular ice core and coral records, and the physics of climate models through paleoclimate data assimilation to provide a complete spatial multi-field reconstruction of climate variability in the tropics and Antarctic. This allows for studying both the year-to-year and multi-decadal variability of the tropical-Antarctic teleconnections. As data assimilation provides a climate reconstruction that is dynamically constrained, the contribution of the tropical variability on the West Antarctic climate changes can be directly assessed. Our results indicate that climate variability in the tropical Pacific is the main driver of ASL variability at the multi-decadal time scale, with a strong link to the Interdecadal Pacific Oscillation (IPO). However, the deepening of the Amundsen Sea Low over the 20th century cannot be explained by tropical climate variability. By using large ensembles of climate model simulations, our analysis suggests anthropogenic forcing as the primary driver of this 20th century ASL deepening. In summary, the 20th century ASL deepening is explained by the forcing, but the multi-decadal variability related to the  IPO is superimposed on this long-term trend.
Ground and Ionospheric Signatures of Solar Wind-Magnetosphere Interaction at Mid-Latitudes
Authors: Gülay Ezgi , Kaymaz Zerefşan , Kalafatoğlu Eyigüler Emine Ceren
Published: February 2023

As we enter the increasing solar activity epoch, the space weather phenomena and predictions become crucially important to avoid the effects on our lives and technology which is becoming more space-dependent every day. One of the key issues in space weather is to determine the worldwide signatures of the solar wind-magnetosphere-ionosphere coupling. While the response of the high and low latitude regions on Earth to the space weather phenomena is well established, the signatures at the mid-latitudes comparatively are less explored. Being farther from both the auroral and the equatorial latitudes, mid-latitude signatures of the solar wind-magnetosphere interaction can be more complex and may not be so straightforward. In this study, the effects of the geomagnetic activity are investigated using observational tools which are unique to its geographical region, north-west Turkey. Dynasonde radar measurements (Dynasonde at ITU Campus, 41°N, 29°E), magnetotelluric measurements of ground electric field (Magnetotelluric station at Bozcaada, 39.5°N, 26°E), and geomagnetic field variations (Geomagnetic observatory at Iznik, 40.43°N, 29.72°E) are combined to obtain a global perspective of the space weather effects in this mid-latitude region. Magnetically active periods were determined using Dst index and the variations in the corresponding ionospheric electron density and the geomagnetically induced currents (GICs) were analyzed based on the case studies as well as statistical tools.  More than 20 indicators such as differences in the fields, extreme values, averages, and storm durations were analyzed and their relations to magnetic storms as well as solar wind and interplanetary magnetic field (IMF) connections were studied.  GICs were investigated based on the variations in the horizontal magnetic field. The dependence on the magnetic storm phases was revealed. One of the most intriguing results from both case studies and statistical analysis is that stronger GICs were found in our region during the recovery phase of the geomagnetic storms. The electron density variations indicated both positive and negative effects during the storms.  The magnitudes of the variations for both GICs and electron density variations were determined.  While the case studies indicate close relations with geomagnetic indices, solar wind, and IMF variations, statistical results resulted in small correlation coefficients.  This emphasizes and further indicates the importance of the statistical indicator that is used in the correlation analysis. In this presentation, solar wind-magnetosphere connection to the ionosphere and to the ground will be discussed in view of our findings.  It is believed that these results will improve our understanding of the cause-and-effect of the space weather phenomena at mid-latitudes while at the same time, it will give support to global space weather modeling studies.
Stochastic resonance, climate variability, and phase-tipping: The increasing risk of extinction in cyclic ecosystems
Authors: Alkhayuon Hassan , Tyson Rebecca , Wieczorek Sebastian
Published: February 2023

Global warming is expected to lead to increase in amplitude and autocorrelation in climate variability in most locations around the world. These changes could have a great and imminent impact on ecosystems. In this work, we demonstrate that changes in climate variability can drive cyclic predator-prey ecosystems to extinction via so-called phase tipping (P-tipping), a new type of instability that occurs only from certain phases of the predator-prey cycle. We coupled a simple mathematical model of climate variability to a self-oscillating paradigmatic predator-prey model. Most importantly, we combine realistic parameter values for the Canada lynx and snowshoe hare with actual climate data from the boreal forest to demonstrate that critically important species in the boreal forest have increased likelihood of extinction under predicted changes in climate variability. The cyclic populations of these species are most vulnerable during stages of the cycle when the predator population is near its maximum. We identify stochastic resonance as the underlying mechanism for the increased likelihood extinction.
Update to the SISAL speleothem database -- links to monitoring data, additional palaeoenvironmental proxies and enhanced accessibility
Authors: Kaushal Nikita , Wilhelm Micah , Lechleitner Franziska , Braun Kerstin , Rehfeld Kira , Gabor Hatvani Istvan , Tanos Peter , Ritzau Magdalena , Skiba Vanessa , Azennoud Khalil , Gabor Szucs Jozsef , Kern Zoltan , Burstyn Yuval , Ait Brahim Yassine
Published: February 2023

Speleothems (cave carbonates) are widely distributed in terrestrial regions, and provide highly resolved records of past changes in climate and ecosystem conditions, encoded in the oxygen and carbon isotope proxies. The SISALv2 database, created by the PAGES-SISAL  Phase 1 Working Group, provided 700 speleothem records from 293 cave sites, 500 of which have standardized chronologies. The database provided access to records that were hitherto unavailable in the original publications and/or repositories, and enabled regional-to-global scale analysis of climatic patterns using a variety of approaches such as data-model comparisons. During the three  year run of SISAL Phase 2,  the working group members have: (i) explored ways to synthesize modern cave monitoring data to provide robust modern baselines and improve proxy interpretations(ii) added trace element proxies of Mg, Sr, Ba, and U concentrations, and Sr isotopes to a new SISAL database version to increase our understanding of regional climatic variability.(iii) updated the SISAL database to incorporate an additional ~100 speleothem stable isotope datasets (iv) and created an online interface web app (The SISAL App) with a user-friendly GUI to increase SISAL data accessibility.Here, we present ongoing work synthesizing cave monitoring data, a summary of speleothem proxy records available in the SISALv3 database update and of ongoing Working Group research projects and a simple use case of The SISAL App. We briefly present a synopsis of the SISAL-community level discussions on best practices for reporting trace element data, and reducing data measured with high resolution laser ablation methods. We conclude with a short discussion on research projects based on the latest SISAL database update and discuss ideas for potential future SISAL phases and projects. For this, we encourage participation and collaboration from researchers in different stages of their academic career and working in different geographical regions and allied disciplines interested in exploiting the new SISAL database version. 
Normal faulting interaction revealed by out-of-phase Quaternary uplift-rate changes implied by studying deformed marine terraces
Authors: Meschis Marco , Roberts Gerald , Robertson Jennifer , Mildon Zoe , Sahy Diana , Goswami Rajasmita , Sgambato Claudia , Faure Walker Joanna , Michetti Alessandro Maria , Iezzi Francesco
Published: February 2023

We have mapped and refined the chronology of raised and tectonically deformed Middle-Upper Pleistocene marine terraces in the Messina Strait, southern Italy, within the upper plate affected by crustal extension above the Ionian Subduction Zone. We have mapped up to thirteen palaeoshorelines which identify Middle-Upper Pleistocene sea-level highstands. Our interpretation reveals the chronology and geometry of deformation since ~500 ka for the Reggio Calabria Fault, the Armo Fault and the Messina-Taormina Fault. We show that the spatial patterns of uplift vary both along the strike of these normal faults and through time, and, given the across strike arrangement of the faults, also reveal how the contribution of each fault to the regional strain-rate developed through time. For example, uplift-rates mapped within the footwalls and hangingwalls of the investigated active faults were not constant through the Upper Pleistocene, with a marked change in the location of strain accumulation at ~50 ka. Conversion of uplift rates into fault throw-rates suggests that the three faults has similar throw-rates prior to ~50 ka (in the range 0.77–0.96 mm/yr), with the Armo and Reggio Calabria faults then switching to lower rates (0.32 mm/yr and 0.33 mm/yr respectively), whilst the Messina-Taormina Fault accelerated to 2.34 mm/yr. The rate of regional extension, which has been approximated by summing the implied heave rates across the three faults, was constant through time despite this re-organisation of local strain accumulation at ~50 ka. We explain these out-of-phase fault throw-rate changes during the constant-rate regional extension conditions as due to interactions between these upper plate normal faults. We discuss how fault throw-rates changing through time may affect a long-term seismic hazard assessment within active normal fault systems.
Effect of Organic Fertilization and Deficit Irrigation Management on Processing Tomato
Authors: Shrestha Jenny , Locatelli Silvia , Nicoletto Carlo , Morbidini Francesco , Zanin Giampaolo , Franklin Dorcas , Sambo Paolo , Maucieri Carmelo
Published: February 2023

An experiment was carried out to determine if organic fertilizer and deficit irrigation combination could replace the traditional management of processing tomato crop (mineral fertilizer and irrigation of 100% crop evapotranspiration, ETc), without affecting yield and quality of production. The study was conducted from June 2022 to September 2022 at the experimental farm of the University of Padova, adopting a split-plot experimental design. The experiment was conducted under a plastic tunnel greenhouse where only the roof was covered to avoid the rainfall influence and at the same time to permit air circulation. Four fertilizer treatments, control (no fertilization), mineral fertilizer, unseived compost, and sieved compost (< 2mm) were applied in factorial combination with two irrigation treatments, 100% ETc and 75% ETc. Data on the vegetative, physiological, yield, and quality parameters were collected. The maximum plant height (75.3 cm) and stem diameter (17.0 mm) were recorded on plants fertilized with unseived compost; both of these parameters did not show significant differences in response to the irrigation level. For physiological parameters, significant differences were found among irrigation treatments. During the daytime, the 25% reduction of optimal irrigation water volume determined a reduction of 4.6% for stomal conductance (0.372 mol m-2 s-1 at 100% ETc) and of 14.2% for transpiration (4.56 mmol m-2 s-1 at 100% ETc). Regarding fluorescence, the highest value (0.769) was recorded for 75% ETc and mineral fertilization, while the lowest (0.733) was for 100% ETc and mineral fertilization. The number of ripe fruits per plant was significantly higher in the treatments with compost (60 fruits plant-1) than in the unfertilized control (39 fruits plant-1). The yield was neither influenced by fertilization nor by irrigation level showing an average value of 2 kg plant-1. Similarly, the qualitative analysis of the tomato fruits showed significantly higher soluble solid content (+5.8%) and pH (+1.4%) at 100% ETc than 75% ETc which showed an average value of 4.11 ˚Brix and 4.20, respectively. The fruits' dry matter content was not significantly influenced by the studied treatments. The results were derived from one year experiment, and they have to be confirmed in future experiments. However, they indicate that compost, whether sieved or not can be a valuable solution for the processing tomato fertilization and that deficit irrigation can be a valuable solution to reduce agricultural water use with only a few effects on plant production and quality parameters.
Multi-scale comparison of rainfall measurement with the help of a disdrometer and a mini vertically pointing Doppler radar
Authors: Seppe Silva Mateus , Vieira Casanova Monteiro Rodrigo , Jose Jerry , Gires Auguste , Tchiguirinskaia Ioulia , Schertzer Daniel
Published: February 2023

Local rainfall measurements can be done in a significant range of methods which rely on very different underlying measurement concepts and assumptions. As an illustration, mechanical rain gauges collect small rainfall amounts; optical disdrometers assess size and velocity of each drop passing through a sampling area, while  Doppler sensors derive a rain rate from estimated average fall velocity. Hence, the quality of the measurements can vary a lot, depending on factors such as rain drop size, wind velocity, rain rate etc. Understanding the differences between various technologies enables us to determine the most reliable device depending on each raining condition. This research aims to compare the performance of two of those devices: the optical disdrometer Parsivel2 (manufactured by OTT) and a mini Doppler radar part of a mini Meteorological Station (manufactured by Thies). The comparison was done with two research focuses: by evaluating the scaling features of the fields measured by both instruments utilizing the framework of Universal Multifractals (UM) to have a performance assessment valid across scales and not only separated scales, and by analyzing the influence of physical parameters namely drop size, wind velocity and rainfall rate in the performance of the devices.The data used was collected on a meteorological mast located in the Pays d’Othe wind farm, 110km southeast of Paris. This measurement campaign is part of the RW-Turb project (https://hmco.enpc.fr/portfolio-archive/rw-turb/; supported by the French National Research Agency (ANR-19-CE05-0022). The mast is operated with two sets of devices, one around 75m in height and the other around 45m. The observation time step of the Parsivel2 is of 30 seconds, and it measures full binned drop size and velocity distribution, while the mini station provides data (rainfall, 2D wind, temperature, pressure, humidity) with 1 second time step. In general, the mini-doppler radar is found to measure a smaller amount of rain with regards to the  Parsivel2. More precisely, we found that the mini doppler radar returned very low rain measurements when subjected to rain conditions with a bigger mean drop size (Dm), and that heavy wind was related to a non-detection of the field in situations with light rain. Scaling analysis enabled us to show that mini Doppler radar exhibited white noise from observation scale smaller than 4s. Hence, it was used only with large time steps. UM analysis also revealed different scaling behaviour for mini Doppler radar rain data at finer temporal resolution than that of Parsivel (30 s).  
Polyphased contractions inside the Sicily Channel Rifting Zone: new evidence from seismic reflection profiles analysis and geodynamic implications
Authors: Maiorana Mariagiada , Artoni Andrea , Chizzini Nicolò , Le Breton Eline , Sulli Attilio , Torelli Luigi
Published: February 2023

The Sicily Channel, located in the foreland area of the African plate, is a very interesting geological area in the Western-Central Mediterranean, as it has undergone different tectonic processes because of its proximity to the convergence zone with the European plate. Extension and opening of a rift zone (Sicily Channel Rift Zone, including the Pantelleria, Malta, and Linosa grabens) occurred in the lower plate of the subduction zone marked by the Gela Thrust System and the Calabrian Accretionary Wedge, respectively located south and south-east of Sicily, and the Maghrebian chain to the west. We analyzed geological and geophysical data, such as variable penetration seismic reflection profiles integrated with borehole data; these allowed us to investigate subsurface structures down to the crust-mantle boundary. The crustal profile shows a Moho deepening down to 11.8 s/(TWT) under the Gela Thrust System and going up to 8 s/(TWT) under the Linosa Graben. Moreover, the presence of several hyperbolae zones and signal anomalies have been linked to a rise of deep fluids associated with mantle uplift and, upward, to magmatic intrusions. The sub-surface also shows evidence of a N-S oriented zone, from the Gela Thrust System to the Malta and Linosa grabens, which has undergone contractional tectonic events superimposed on previous extensional structures. Throughout this area, from the Early-Middle Miocene to the Early Pliocene, an extensional event occurred in association with the slab roll-back of the African Plate. In this phase, several volcanic intrusions concentrated near the grabens’ rims suggest a relation between the extension, the Moho rising, and the magmatic manifestations.  Afterward, a compressional event in the Madrepore and Malta Grabens was registered. This event has been correlated to the advance of the Gela Thrust Front, which, according to literature bio-chronostratigraphic analysis, had three stages of advancement in Zanclean, Piacenzian and Chibanian. Furthermore, a recent contractional event caused the folding of the seafloor in the central part of the Malta Graben. This latter phase has been related to a potential change in the subduction polarity. These results provide new insights into the regional kinematic setting of the Sicily Channel, suggesting that strain located within the African Plate can be explained through the overlapping of both intra-plate (localized asthenospheric rise) and inter-plate (compression transmitted from surrounding mountain belts) processes ongoing between Europa and Africa. Indeed, the Sicily Channel structural setting resulted from the interplay of the rollback of the African slab, the consequent changes in the asthenospheric flow that caused extension and local magmatic intrusions, and the active subduction front and its potential polarity reversal that caused local and polyphased compressional pulses.
Spectroscopic Studies and Confirmatory Geochemical Analyses of Rare Earth Element Bearing Rocks from the Neoproterozoic Siwana Ring Complex, Rajasthan, India
Authors: Imran Saraah , Goswami Ajanta , Saikia Angana , Kumar Rai Hrishikesh , Jyoti Barman Bijan
Published: February 2023

Abstract:Rare earth elements (REEs) are of high economic value owing to their electronic, magnetic, optical, catalytic, and phosphorescent properties, thereby making them an important part of the development of green technology. They exhibit characteristic sharp absorption features in reflectance spectra in the visible-near infrared (VNIR) to short-wave infrared (SWIR) region due to their 4f-4f orbital intra-configurational electronic transitions.In this study laboratory based close-range imaging spectroscopy techniques are used along with confirmatory geochemical analytical techniques (petrography, ICPMS, SEM and EPMA) to study 20 samples collected from REE-bearing rocks of the Neoproterozoic Siwana Ring Complex (SRC), a collapsed caldera structure situated in Barmer District, Rajasthan (India).The SRC is an anorogenic, rift-related bimodal volcano-plutonic rock association belonging to the Malani Igneous Suite. It comprises of felsic and basic volcanic lava flows, rhyolite, peralkaline granite, pyroclastics, tuff and later microgranite, aplite and felsite dykes.The spectral reflectance curves of the samples collected using an ASD FieldSpec4 (350-2500 nm) exhibit characteristic absorption dips at 439, 491, 580, 740 and 800 nm indicating the presence of Nd3+. Other major absorption dips are attributed to the presence of Sm3+, U4+, etc. Various combinations of absorption features in the VIS-SWIR region indicate the presence of minerals like biotite, epidote, chlorite, nontronite, goethite, and REE fluorocarbonates. The Fourier Transform Infrared (FTIR) spectra of the samples collected using a Thermo Fisher Scientific Nicolet 6700 (400-4000 cm-1) show symmetric and asymmetric bending and stretching vibration features of Si-O, P-O and O-H bonds, which are diagnostic of minerals like aegirine, riebeckite, and REE minerals like monazite apart from other major silicate minerals like quartz and feldspar. The presence of these minerals is confirmed by mineral chemistry, bulk and trace element data.The observations from the spectroscopic studies seem to correlate well with data obtained from various geochemical analyses. This study provides spectroscopic information on the rocks from SRC for the first time. It shows the proficiency of spectroscopic studies as a cost-effective and non-destructive technique for the identification of REE minerals which can be used before detailed geochemical and mineralogical studies as well as future exploration.Keywords: Siwana Ring Complex, Spectroscopy, REEAbbreviations:ASD – Analytical Spectral Devices, Inc.EPMA – Electron Probe Micro AnalyzerFTIR – Fourier Transform InfraredICPMS – Inductively Coupled Plasma Mass SpectrometryREE – Rare Earth ElementsSRC – Siwana Ring ComplexSWIR – Short Wave InfraredVNIR – Visible Near Infrared
Resolving Late Cretaceous intra-plate magmatism emplacement models and plate motion on the West Iberian Margin
Authors: Araújo Bruno , Pereira Ricardo , Duarte João , Mata João
Published: February 2023

The West Iberian Margin (WIM) was a locus of significant post-rift Late Cretaceous magmatism coeval with multiple intraplate magmatic events on the Central-North Atlantic. The effects of the migration of the Iberian microplate on the location of the distinct magmatic occurrences are here investigated.At the WIM and within this magmatic cycle, the Sintra, Sines and Monchique intrusive massifs, the Lisbon Volcanic Complex and distinct sill complexes were emplaced on the onshore continental margin. Several coeval oceanic seamounts, are also evaluated in terms of age and location for the assessment of how plausible the combined effects of plate motion and underlying mantle contributions are to their origin.Using GPlates software we assess the different mantle mechanisms that can explain magmatic upwelling in the region, including: 1) plume, whether static or mobile ones; 2) edge-driven convection; or 3) stationary superplume with secondary plumelets.The preliminary results suggest that a stationary superplume emitting distinct secondary plumelets is the preferred model for the distinct and diachronous magmatic features that pierced the crust as the Iberian microplate moved along a non-linear path. This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020- IDL and UIDB/04035/2020- GeoBioTec.
Analysis of the Genesis Potential Index in Subtropical Cyclones off the Coast of Brazil
Authors: Ribeiro João Gabriel Martins , da Paz Gabriel Teodoro , Reboita Michelle Simões , Gozzo Luiz Felippe , Ferreira Glauber Willian de Souza , da Rocha Rosmeri Porfírio
Published: February 2023

The coastal region of southern and southeastern Brazil, which is part of the South Atlantic Ocean basin, is a genesis region for subtropical cyclones and, therefore, is susceptible to weather changes caused by these systems. The first named subtropical cyclone in the South Atlantic basin was Anita in 2010. Since then, some studies on subtropical cyclones have been carried out, but there are still several questions to be investigated. Thus, this study aims to: (a) describe the main physical mechanisms of genesis of the subtropical cyclones that were named in the South Atlantic Ocean between 2010 and 2021 and (b) identify the value of the Genesis Potential Index (GPI) between the pre-cyclogenesis and the phase in which these systems acquire subtropical characteristics. The rationale for analyzing the CPI is that we want to identify a possible pattern that helps in operational weather forecasting. The main database used in the study is the ERA5 reanalysis. Of the 14 cyclones studied, only two systems did not have cyclogenesis with subtropical characteristics, but acquired it 24 hours after cyclogenesis. The results indicate that 5 cyclones have a genesis associated with mid-level troughs in the atmosphere, and 9 with blocking patterns (cutoff low type). As most of the cyclones studied occur in an environment with blocking structure, this indicates that the condition of weak vertical wind shear is an important factor for subtropical cyclones. As the GPI does not show a standard value in the 14 cyclones studied, between pre-cyclogenesis and the moment when these systems become subtropical, as it varies from 0.35 in the Deni genesis to 22.71 in the Anita genesis, perhaps it is not possible to use it with a threshold in operational practices. The authors thank Programa de P&D regulado pela ANEEL e empresa Engie Brasil Energia e a Companhia Energética Estreito for the financial support.
Topography and climate dictate soil NPK stoichiometry across Africa
Authors: Kebonye Ndiye Michael , Taghizadeh-Mehrjardi Ruhollah , Agyeman Prince Chapman , John Kingsley , Kakhani Nafiseh , Scholten Thomas
Published: February 2023

Optimal soil nitrogen-to-phosphorus-to-potassium (NPK) stoichiometry is critical for agricultural production in Africa because it presents the appropriation of input materials to avoid limited or excessive fertilizer applications. Furthermore, an optimum nutrient supply to the plants is crucial to mitigate or eliminating Africa’s food crisis. However, what drivers influence its levels, distribution and variability across different landscapes and scales? Insights regarding these aspects are necessary for (1) the derivation of robust policies associated with crop production and food security, (2) monitoring of changes associated with hotspot areas between NPK stoichiometry and designated drivers, (3) instigation of suitable and well-targeted efforts to ensure that areas with optimal soil NPK levels are maintained since these eventually affect and influence crop yield output, and (4) identification of areas that are imbalanced in NPK content of the soils and thus may need fertilization. Freely accessible major soil nutrient data [i.e., nitrogen (N), phosphorus (P) and potassium (K)] for Africa were obtained from the iSDAsoil platform, aggregated to 250 m, and used to compute the NPK stoichiometry estimate. In addition, similar NPK stoichiometry estimates were derived for national-scale major food crop exporters, including South Africa, Ethiopia, and Malawi. All these across-scale NPK stoichiometry estimates coupled with different driver estimates (e.g., human activities/agricultural activities/cropping systems, soil texture, soil pH, etc.) provided the data used to assess pairwise mechanistic and explainable model insights using structural equation models [SEM(s)] plus partial dependence plots (PDPs) respectively. Climate-related factors along with topography were the main direct drivers of NPK stoichiometry connected to the topsoil of Africa (i.e., the entire continent including some selected nations).  Human-related activities contributed less to soil NPK stoichiometry. Interestingly, aboveground biomass was discovered to be interdependent with NPK stoichiometry. This cross-scale benchmark alludes to the variations in NPK stoichiometry under both changing climatic conditions and topography in Africa.
Keywords: NPK Stoichiometry, Soil Nutrients, Climate Change, Food Security, Structural Equation Modeling, Topographic Effects, Nitrogen, Phosphorus, Potassium, Africa
 
Landslide Susceptibility Model based on Random Forest classification
Authors: Sirbu Flavius
Published: February 2023

Random Forest (RF) is a classification algorithm used successfully in geomorphological and hazard mapping (Sîrbu et al., 2019). It performs a defined number of classifications, based on decision trees, on random samples with replacement, from the original training data. Because of this, the algorithm is especially robust for errors and outliers in the training data and it is also very good in producing uncertainty estimates for the variability of results on each of the classified features. Its resulting data can also be used, with different methods, to produce a ranking of the independent variables used in the classification.The present study was performed on a given data set, in central Italy, containing 7,360 slope units covering an area of 4,095 km2. The slope units are classified twice, based on different methodologies, into units with or without landslides. Also each slope unit has assigned 26 attributes that were used as independent variables (Alvioli et al., 2022). The slope units are treated as spatially independent from each other, and have been randomly split 70%-30%, into training and validation data respectively.The model was setup as a computer code, in the R software environment. It uses different libraries to integrate the input data, run the algorithm, run a validation and measure the performance of the model and finally produce the output data. Most of the model settings were used with their default value, with the number of classification trees (ntree) being the only important setting that was fine tuned to a value of 1501 based on different model runs.The results of the two classifications (one for each classification of the dependent variable) are relatively similar, proving once again the robustness of the RF algorithm when it comes to minor to medium changes in the input data. The first classification had an AUC (area under the curve) value of 0.829 compared with the AUC value of 0.817 for the second classification. For each classification, a ranking of the independent variables was produce, with the standard deviation of slope being the most important predictor. Other predictors with relative high importance were elevation and curvatures.The results show that RF is an important classifier, which can be used with relatively low custom settings and on almost any data set in order to produce a reliable susceptibility map. Its integration with the R software makes it easy to run the whole process virtually automatic. The computer code for the model will be made freely available.
Parameterization-based uncertainties in RegCM simulations over the Carpathian region in a wet year
Authors: Kalmár Tímea , Pongrácz Rita , Pieczka Ildikó
Published: February 2023

Precipitation is one of the most important climate variables in many aspects due to its key impact on agriculture, water management, etc. Furthermore, extreme precipitation events can lead to excess surface water and floods and are becoming an amplifying societal cost as a result of urbanization and our warming climate. However, it remains a challenge for climate models to realistically simulate the regional patterns, temporal variations, and intensity of precipitation. Detailed knowledge about extreme precipitation events is important for advanced predictions on weather-to-climate time scales. The difficulty arises from the complexity of precipitation processes within the atmosphere stemming from cloud microphysics, cumulus convection, large-scale circulations, planetary boundary layer processes, and many others. This is especially true for heterogeneous surfaces with complex orography such as the Carpathian region.In order to quantify the impact of the use of different parameterization schemes on regional climate model outputs, hindcast experiments were completed applying RegCM4.7 to the Carpathian region and its surroundings at 10-km horizontal resolution using ERA-Interim reanalysis data as initial and boundary conditions. In this study, 24 simulations were carried out by using various combinations of the physics schemes (2 land surface, 2 microphysics, 3 cumulus and 2 boundary layer schemes) for the year 2010, which was the wettest year in the region since the beginning of the regular measurements. Each parameterization combination leads to different simulated climates, so their spread is an estimate of the model uncertainty arising from the representation of the unresolved phenomena. The analysis of the RegCM ensemble indicates systematic precipitation biases, which are linked to different physical mechanisms in the summer and winter seasons.Based on the results, RegCM is sensitive to the applied convection scheme, but the interactions with the other schemes (e.g., land surface or microphysics) affect not only the total precipitation, but also the convective and stratiform precipitation in some cases. Due to the different treatment of moisture in the schemes, there are differences not only between the representation of the precipitation cycle, but also in other climatological variables such as soil moisture, temperature and cloud cover.