Eastern Section Research Articles

The Identification of Landslide Risk-Prone Areas in the Imbulpe Divisional Secretariat in Sri Lanka: A GIS-Based Multi-Criteria Decision Analysis

Landslides can be identified as a prominent natural hazard that causes significant loss of life and property damage in many parts of the world and Sri Lanka. Planning experts, local governments, and decision-makers can benefit greatly from the identification of landslides and the creation of landslide susceptibility maps. Accurate landslide susceptibility maps are essential to minimize the loss of life and property. The landslide risk zones in any area can be plotted using GIS-based MCDA techniques that integrate the Analytic Hierarchy Process (AHP) and Weighted Linear Combination (WLC) functions in ArcMap. This study attempted to develop a multi-criteria decision analysis for the appraisal of landslide risk zones in the Imbulpe DSD in Rathnapura District. To analyze the danger of landslides, MCDA was used in conjunction with GIS as a spatial decision-making tool. Slope, drainage pattern, soil type, geology, land use, and rainfall pattern were the six factors used in the study. Landslide risk maps were produced based on weighted techniques such as Analytic Hierarchy Process and Weighted Linear Combination. The slope area significantly affects the likelihood of a landslide. Results revealed that landslides were spreading in a manner that extended toward the eastern section of the study area. Because there are no good locations to build houses in the study area, a huge number of individuals tend to live in unprotected areas. The majority of the landslides in the area occurred during May, October, and November because those months received heavy rainfall. As remedial actions, it can be proposed to displace people living under landslide risk in the northeast and northwest slope areas to suitable protected areas.

Examining the performance of along-track multi-mission satellite altimetry – A case study for Sentinel-6

Abstract Satellite altimetry (SA) is one of the most valuable techniques that measure the sea level data at both the near-coast and offshore. There exists, however, multiple challenges and hindrances in determining and using accurate sea level data. The most pertinent is that evaluation of SA performance requires that all data sources (such as tide gauges (TG) and hydrodynamic models (HDMs)) refer to the same vertical datum. Thus, knowledge of the geoid (equipotential surface of the earth) is essential in linking different sources of sea level. Accordingly, this study examines performance of along-track data for three satellite missions (Sentinel-3A, Jason-3, and Sentinel-6A) to obtain realistic sea level variation and to determine the accuracy of the various missions in the complex area of the eastern Baltic Sea. The methodology consisted of utilizing SA, HDM, and TG data and a high-resolution geoid model. Results show that root-mean-square error (RMSE) varied for Jason-3 within a range of 1.68–50.14 cm, Sentinel 3A with a range of 2.8–46.27 cm, and Sentinel 6A with a range of 3.5–43.90 cm. Sentinel 6A was determined to be the most accurate and reliable satellite mission. Results also showed higher RMSE (15.7–46.2 cm) during (i) the seasonal sea ice month (e.g. March 2018); (ii) at locations of several islands (e.g. eastern section of Gulf); and (iii) at locations where rivers discharged into the Gulf (e.g. Nava, Kemi, Luga, and Neva rivers). These features tended to show up as peaks in the final results even though robust data processing for outliers were undertaken. These results suggests that improvements can still be made in the SA retrackers and also in the data-processing techniques utilized.

Transition from orogenic-like to anorogenic magmatism in the Southern Alps during the Early Mesozoic: Evidence from elemental and Nd-Sr-Hf-Pb isotope geochemistry of alkali-rich dykes from the Finero Phlogopite Peridotite, Ivrea–Verbano Zone

The Ivrea-Verbano Zone (IVZ) in the westernmost sector of the Southern Alps is an iconic upper mantle to lower continental crust sequence of the Adriatic Plate and provides a geological window into the tectono-magmatic events that occurred at the Gondwana–Laurussia boundary from Late Paleozoic to Early Mesozoic. In this work, we document new geochemical and Nd-Sr-Hf-Pb isotopic data for Early Mesozoic alkali-rich dyke swarms which intruded the Finero Phlogopite Peridotite (northern IVZ) to provide geological constraints on the nature, origin and evolution of Early Mesozoic magmatism in the Southern Alps. The studied dykes are amphibole-phlogopite-bearing and show geochemical features varying between two end-member groups. A dyke group is characterized by HFSE-poor, Al-rich amphibole (Al2O3 up to 16 wt%) with high LILE and LREE contents, high radiogenic 87Sr/86Sr(i) (0.704732 to 0.704934) and low radiogenic Nd isotopes (εNd(i) from –0.1 to –0.7), which support the occurrence of significant amounts of recycled continental crust components in the parental mantle melts and impart an overall “orogenic-like” affinity. This dyke group was largely derived from metasomatized lithospheric mantle sources. The second group is HFSE-rich with Al-poorer amphibole enriched in LILE and LREE, low radiogenic 87Sr/86Sr(i) (0.703761–0.704103) and higher radiogenic Nd isotopes (εNd(i) from +3.4 to +5.4) pointing to an “anorogenic” alkaline affinity and asthenospheric to deep lithospheric mantle sources. Some dykes show both orogenic and anorogenic affinities, providing evidence that the orogenic-like magmatism in the IVZ predates the alkaline anorogenic magmatism. The Finero dyke swarms therefore record a geochemical change of the Early Mesozoic magmatism of the Southern Alps from orogenic-like magmatism, typical of post-collisional settings, to anorogenic alkaline magmatism, common in intraplate to extensional settings, and places a temporal correlation of Early Mesozoic magmatism in the IVZ to those in the eastern and central sectors of the Southern Alps.

Tropical cyclone activity around Taiwan modulated by El Niño during 1900–1945 and 1970–2015

AbstractTropical cyclone (TC) activity around Taiwan is analysed via typhoon datasets compiled by the Central Weather Administration (CWA) for the pre‐satellite era of 1900–1945 (IE1) and the satellite era of 1970–2015 (IE2). Modulating processes imposed by El Niño years on active and inactive TC activity around Taiwan in the July–September season are examined and compared between IE1 and IE2. Analyses reveal coherent dynamic relationships between TC variability in Taiwan and large‐scale modulating processes; furthermore, modulating processes exhibit similar features between IE1 and IE2. El Niño years tend to have more (less) TC formation in the eastern (western) sector of the western North Pacific (WNP). In both IE1 and IE2, intensified TC activity around Taiwan is associated with northwestward TC tracks from the eastern WNP toward Taiwan assisted by a westward‐elongating cyclonic anomaly across the WNP and South China Sea. When a WNP cyclonic anomaly stretches northwestward toward oceans north of Taiwan, TCs from the tropical eastern WNP generally move northward toward oceans east of Taiwan to result in suppressed TC activity around Taiwan. The westward‐elongating anomalous cyclone is associated with an anomalous divergent centre over the Indian Ocean and an anomalous convergent centre in the tropical eastern Pacific over the 150°–130°W region. The northwestward‐extending anomalous cyclone connects with an anomalous divergent centre over the Maritime Continent and an anomalous convergent centre over the 130°–110°W region. Anomalous divergent and convergent centres displace westward (eastward) for active (inactive) TC types that are related to a more westward (eastward) maximum centre of anomalous warm waters in the tropical eastern Pacific. The above coherent dynamic relationships justify the reliability of TC records compiled by the CWA during IE1 and IE2.

Geology of the Mutis Complex, Miomaffo, West Timor

Mesozoic forearc assemblages are widespread across Indonesia, and these are also exposed in the overthrust terranes on Timor. The oldest rocks in the allochthonous Mutis Complex, West Timor are Mesozoic basaltic volcaniclastic rocks and melange containing blocks of normal mid-ocean ridge basalt (N-MORB) basalt (194 ± 5 Ma), amphibolite (metamorphism at 184 ± 6 Ma), garnet and actinolite-bearing schists, arkosic sandstone and volcanogenic sedimentary rocks. Based on the large component of Jurassic material, these rocks were probably derived from the Woyla terrane. The eastern part of the Miomaffo massif is complexly deformed with a dominant foliation overprinted by several fold and fault events including late normal cataclastic zones. This sequence is intruded by calc-alkaline andesitic dykes (possibly in the Eocene). The Central Sector of the massif is a block of high-strain greenschist facies rocks where the primary texture can no longer be recognised, but the bulk composition is the same as the volcaniclastic rocks in the east. Further west is an amphibolite facies metamorphic province. Amphibolite from the Western Sector have the same N-MORB composition as the basalt in the east, but the gneissic rocks have a higher proportion of arc-sourced protoliths. The peak metamorphic conditions were 650 °C and 0.9 GPa. This metamorphic event occurred at 37 Ma, reflecting subduction on the southeast margin of Sundaland, whereas the low-grade Mesozoic metamorphism of the Eastern Sector of the massif occurred in the accretionary prism along the Woyla Arc. The Mutis Complex at Miomaffo demonstrates the complex geological history of Mesozoic rocks in eastern Indonesia.

The climate crisis affects Mediterranean marine molluscs of conservation concern

AbstractAimThe Mediterranean Sea is a hotspot of endemism and it is warming at two to three times the rate of the global ocean. The continental masses that surround it constrain species range shifts. Therefore, as seawater temperature increases, distributions of marine species may contract into few small cooler refugia, with consequent risk of extinction from range contraction and fragmentation, particularly for endemics. We assess this risk for 15 molluscs of conservation concern occurring in the Mediterranean Sea. Invertebrates have been rarely assessed so far, despite their diversity and their importance for ecosystem functioning.LocationThe Mediterranean Sea and Eastern Atlantic Ocean.MethodsWe used ensemble species distribution models to project the future range of our target species and assess their IUCN Red List status.ResultsAs hypothesized, our models predicted major range shifts, contractions and fragmentation in the Mediterranean Sea for all species. Under moderate emission scenarios such as RCP4.5, up to 12 of the 15 target species will be eradicated from the eastern and southern warmer sectors. Under severe emission scenarios such as RCP8.5 and by the end of the century, we predict the global extinction of the endemic Patella ferruginea and Pinna nobilis. Non‐endemic species may buffer range loss in the Mediterranean with range gains in the Atlantic Ocean. Still, we predict that only a single species, Zonaria pyrum, will have marginal total range gains in future climate warming scenarios.Main conclusionsEight species will become threatened and the fate of Patella ferruginea and Pinna nobilis contrasts the belief that marine species are less prone to extinction than continental species under a warming climate.

Preservation of chemical and isotopic signatures within the Weißseespitze millennial old ice cap (Eastern Alps), despite the ongoing ice loss

Alpine ice core research has long focused on a few suitable drilling sites at high elevation in the Western European Alps, assuming that the counterparts at lower elevation in the eastern sector are unsuitable for paleoenvironmental studies, due to the presence of melting and temperate basal conditions. However, it has been demonstrated that even in the Eastern Alpine range, below 4,000 m a.s.l., cold ice frozen to bedrock can exist. In fact, millennial-old ice has been found at some locations, such as at the Weißseespitze (WSS) summit ice cap (Ӧtztal Alps, 3,499 m a.s.l.), where about 6 kyrs appear locked into 10 m of ice. In this work, we present a full profile of the stable water isotopes (δ18O, δ2H), major ions (Na+, K+, Mg2+, Ca2+, NH4+, Cl−, NO3−, SO42−), levoglucosan, and microcharcoal for two parallel ice cores drilled at the Weißseespitze cap. We find that, despite the ongoing ice loss, the chemical and isotopic signatures appear preserved, and may potentially offer an untapped climatic record. This is especially noteworthy considering that chemical signals of other archives at similar locations have been partially or full corrupted by meltwater (i.e., Silvretta glacier, Grand Combin glacier, Ortles glacier). In addition, the impurity concentration near the surface shows no signs of anthropogenic contamination at WSS, which constrains the age at the surface to fall within the pre-industrial age.

Inclination Trend of the Agulhas Return Current Path in Three Decades

The Agulhas Return Current (ARC), as a primary component of the Agulhas system, contributes to water exchange and mass transport between the southern portions of the Indian and Atlantic Ocean basins. In this study, satellite altimeter data and reanalysis datasets, and a new set of criteria for the piecewise definition of the jet axis are used to explore the long-term change of the ARC’s axis position in recent three decades. It is found that the ARC axis exhibits a significant slanting trend with its western part (35–48°E) migrating northward and the eastern part (48–70°E) migrating southward. The meridional movement of the ARC path could be attributed to large-scale wind forcing. The anomalous surface wind stress curl, by Ekman pumping mechanism, leads to positive–negative–positive sea surface height anomalies in the western section and negative–positive–negative anomalies in the eastern section, thus the ARC axis tilts accordingly, in a northwest–southeast direction. Further analysis suggests that this ARC slanting trend is more dependent on the southward shift of the downstream axis and less on the topographic steering upstream. The downstream axis is more likely to interact with the ACC fronts and its migration could dominate the local EKE pattern by changing the background circulation and energy cascade direction. For the headstream west of 35°E, the ARC axis is more subject to topography, thus the EKE change is more dominated by eddy activity processes, including shedding, propagation and merging. This study provides some new insights into the long-term change of ARC and its interaction with the local EKE variability.

Lithotectonic architecture of the Paleoproterozoic intracratonic Kaladgi rift basin, southwestern India: Inference from a magnetotelluric study

Peninsular India is traversed by several major Paleoproterozoic rift basins, among which the Kaladgi rift basin is a prominent one. Here, we present results from Magnetotelluric (MT) studies in the eastern section of this rift basin. The data were acquired along a ∼120 km long profile passing through Belavanik-Bagalkot-Ukkali regions covering the Paleoproterozoic intracratonic Kaladgi rift basin, the Cretaceous Deccan volcanic province and the Archean gneisses/granites/greenstones of the Dharwar craton. The lithospheric electrical structure was obtained from joint inversion of TE- and TM-modes data using a 2-D nonlinear conjugate gradient algorithm. The results reveal that the Kaladgi sediments are ∼500–1000 m in thickness overlying a highly fractured crystalline basement. Proterozoic sediments are exposed beneath the Deccan basalt cover and in the shallow fractured zones. The conductive-resistive transitions in the model at the crustal depths correspond to major tectonic faults and deformed crustal rocks. The transition boundary at ∼50 km depth defines the electrical Moho. At the same time, a ∼25 km wide, steep conductive feature from ∼75 km to upper mantle lithosphere depths (∼180–200 km) is interpreted as the trace of the Chitradurga Suture Zone (CSZ). The observed crustal heterogeneity, conductivity variations, and resistive lithosphere are attributed to the geological history of the region, including Archean collisional events and subsequent reactivation associated with the Reunion hotspot. The crustal conductors are associated with mafic intrusions from the underplated basalts, and also the high conductivity may be due to the sulfide mineralization in the fault zones. The MT study provides valuable insights into the deep tectonic framework of the region.

Sequential Direct and Inverse Modeling of Underground Flows in the Upper Cheliff Alluvial Aquifer, Algeria

The Upper Cheliff plain lies 125 km south-west of Algiers, capital city of Algeria. It is characterized by its unconfined aquifer contained in a heterogeneous filling of Mio-Plio-Quaternary age. Nowadays, this aquifer is severely exploited to meet the domestic, industrial and agricultural needs in the region. Groundwater resources management by means of numerical modeling is highly required in order to improve our knowledge of the hydrogeological operation of this aquifer. In this work we implemented an approach based on a sequential solving of the direct and inverse problems. In the case of the direct problem, steadystate flow simulations revealed the persistence of large discrepancies between the measured and calculated piezometric levels, which reflect the heterogeneity of the aquifer. The zonation provided by the direct method, based on the conceptual model, is then fed in the inverse method. The latter, in addition to its speed and its convergence, made it possible to reduce the disparities with measurements as noted in the direct method. The main results highlight a heterogeneous hydraulic conductivity distribution which reaches its highest values in the central and north-western sectors of the aquifer, whereas the lowest values are found in the eastern, northern and southern sectors of the aquifer. Furthermore, calculation of the groundwater flow budget by the inverse model showed that rainfall recharge is the main input into the aquifer with 462.5x103 m3/day, whereas the most important outlet of the aquifer is the Cheliff Wadi with a flow rate of 627x103 m3/day.

Geo-statistical analysis of climatic variability and trend detection in the Hindu Kush region, North Pakistan.

This paper is an effort of geo-statistical analysis of rainfall variability and trend detection in the eastern Hindu Kush region located in the north-west of Pakistan. The eastern section of the HK region lies in the western part of Pakistan. Exploring rainfall variability and quantifying its trend and magnitude is one of the key indicators among all climatic parameters. In the study area, Pakistan Meteorology Department (PMD) has established seven meteorological stations: Drosh, Chitral, Dir, Timergara, Saidu Sharif, Malam Jabba, and Kalam. Daily, mean monthly, and mean annual rainfall time series data for all the met stations were geo-statistically analyzed in the GIS environment for detecting monthly and annual variability in rainfall, variability, and trend detection. Mann-Kendall (MK) and Theil-Sen's slope (TSS) statistical tests were applied to rainfall data. Initially, the MK test was applied for detection of trends and TSS test was used to quantify the change in magnitude. The results indicate that the rainfall variability in intensity and trend pattern detection. The analysis confirms that an extremely significant rainfall trend in the case of mean annual rainfall was predicted at Dir and Malam Jabba meteorological stations. Opposite to this, at Kalam and Chitral stations, a less significant rainfall trend was noted. In a similar context, no prominent rainfall trend has been found at Drosh, Timergara, and Saidu Sharif meteorological stations. Likewise, using TSS, an extremely negative variation in the magnitude of rainfall was verified at Kalam and Malam Jabba. However, a noteworthy positive change in rainfall magnitude has been noted at Dir and Saidu Sharif meteorological stations. The findings of this research have the potential to assist the decision and policy makers and academicians to think truly and conduct more scientific research studies to mitigate climate change.

Using genetic comparisons of populations from Arizona, Mexico, and Texas to investigate fall armyworm migration in the American southwest.

Fall armyworm (FAW) is a global agricultural pest, causing substantial economic losses in corn and many other crops. Complicating efforts to control this pest is its capacity for long distance flights, which has been described in greatest detail for the central and eastern sections of the United States. FAW infestations are also routinely found in agricultural areas in southern Arizona, which lie beyond the western limits of the mapped migratory pathways. Climate suitability analysis found that the affected Arizona locations cannot support permanent FAW populations, indicating that these FAW most likely arise from annual migrations. A better understanding of this migration would provide insights into how large moth populations can move across desert habitats as well as the degree of gene flow occurring between FAW populations across the North American continent. In this study the Arizona populations were genetically characterized and compared to a selection of permanent and migratory FAW from multiple sites in the United States and Mexico. The results are consistent with migratory contributions from permanent populations in the states of Texas (United States) and Sinaloa (Mexico), while also providing evidence of significant barriers to gene flow between populations within Mexico. An unexpected finding was that two genetically distinct FAW subpopulations known as "host strains" have a differential distribution in the southwest that may indicate significant differences in their migration behavior in this region. These findings indicate that the combination of mitochondrial and Z-linked markers have advantages in comparing FAW populations that can complement and extend the findings from other methods.

Radar Characteristics and Causal Analysis of Two Consecutive Tornado Events Associated with Heavy Precipitation during the Mei-Yu Season

This paper comprehensively analyzed two consecutive tornado events associated with heavy precipitation during the Mei-yu season (a period of continuous rainy weather that occurs in the middle and lower reaches of the Yangtze River in China from mid-June to mid-July each year) and detailed the formation and development process of the tornadoes using Doppler weather radar, wind profiler radar, ERA5 reanalysis data, ground automatic station data and other multi-source data. The results showed that: (1) Small-scale vortices were triggered and developed during the eastward movement of the low vortex, forming two tornadoes successively on the eastern section of the Mei-yu front. (2) The presence of a gap on the front side of the reflectivity factor profile indicated that strong incoming airflow entered the updraft. Mesocyclones were detected with decreasing heights and increasing shear strengths. The bottom height of the tornado vortex signature (TVS) dropped to 0.7 km, and the shear value increased to 55.4 × 10−3 s−1. Tornado debris signatures (TDSs) could be seen with a low cross-correlation coefficient (CC) value area of 0.85–0.9 in the mesocyclone. The difference between the lowest-level difference velocity (LLDV) and the maximum difference velocity (MXDV) reached the largest value when a tornado occurred. (3) The continuously enhanced low-level jet propagated downward to form a super-low-level jet, and the strong wind direction and wind speed convergence in the boundary layer created a warm, moist and unstable atmosphere in Suzhou. With the entrainment of dry air, the northwest dry jet and the southeast moist jet stimulated the formation of a miniature supercell. (4) The low-level vertical wind shear of 0–1 km increased significantly upon tornado occurrence, which was more conducive to the formation and intensification of horizontal vorticity tubes. Encountering updrafts and downdrafts, the vorticity tubes might have been stretched and intensified. The first lightning jumps appeared 15 min and 66 min earlier than the Kunshan Bacheng tornado and the Taicang Liuhe tornado. The Liuhe tornado occurred during the stage when the lightning frequency reached its peak and then fell back.

3D structural modeling using seismic data and well logs for Khatatba reservoir in Matruh-Shushan Basin, North Western Desert, Egypt

Middle Jurassic reservoirs present challenges in the northern segment of the Western Desert due to geometric uncertainties arising from structural configurations, lateral facies variations, diverse lithologies, and heterogeneous reservoir quality. Consequently, this study employed an intricate approach, constructing detailed 3D geostatic models by amalgamating diverse datasets, including 2D seismic sections and digital well-logs. The focus of these 3D models was on the Khatatba Formation (Upper-Safa Member, Kabrit Member, and Lower-Safa Member) in Matruh—Shushan Basin in the North Western Desert. The objectives encompassed assessing hydrocarbon potential, precisely estimating reserves, formulating development and exploration strategies, and identifying prospective drilling locations. The resultant structural model revealed a compartmentalized region marked by major and minor NE–SW trending normal faults, establishing structurally advantageous locations for hydrocarbon trapping within the study area. Petrophysical analyses highlighted the promising potential of the Upper-Safa Member as a reservoir, featuring porosity values ranging from 10 to 18%, peaking in the northeast sector, volume of shale (Vsh) between 15 and 24%, water saturation (Sw) spanning from 18 to 53%, and increased sand thickness towards the eastern section. Similarly, the Lower-Safa Member demonstrated favorable reservoir attributes, including porosity values ranging from 10 to 16%, with higher values in the southeastern part, Vsh between 17 and 28%, and Sw varying from 15 to 47%. The study findings underscored the hydrocarbon potential in the northeast block of the study area for the Middle Jurassic Khatatba Formation. These insights contribute valuable information for decision-making in exploration and production endeavors within the basin.

Late holocene progradation in a mixed siliciclastic-carbonate beach ridges system, Northeast Brazil

A morpho-sedimentary analysis based on grain size, texture, composition, luminescence ages, and morphologic pattern was performed in a beach ridge system located on the Brazilian semiarid coast to understand the siliciclastic and bioclastic mixtures during a progradation of strandplain. Moreover, the rhodolith beds were adopted as a new sea-level proxy to analyze the coastline displacement trajectory of the mixed siliciclastic-carbonate sedimentary environment. The beach ridges system shows a succession of ridges and swales interrupted in the central part by a lagoon plain, the western sector exhibits the crest relief related to the ancient foredune on top and underlying foreshore deposits, and the eastern sector shows a great presence of transgressive dunes overlying beach ridges. Foredune/aeolian facies and the foreshore facies (with rhodolith beds associated) show siliciclastic and bioclastic mixture related to the late Holocene coastal progradation with a progressive increase in carbonate influence, mainly calcareous algae, foraminifera, and molluscs. Moreover, comparing the modern counterpart of the older beach ridges, finer and better-sorted sediments were found in the ancient deposits than in the modern ones. Thus, the progradation was marked by an eminently dissipative beach system. This coeval sedimentation is controlled by key local settings, such as the semi-arid climate, the absence of local fluvial input, the shallow shelf, and the carbonate factory for bioclastic supply. The presence of rhodolith beds in the foreshore facies with an elevation lowering trend towards the modern coastline reinforces the hypothesis that the mixed progradational pattern was accompanied by a small fall in sea level, which corroborates with late Holocene regional curves and provides pioneering preliminary contributions for the studied area.

A multi-sensor approach to monitor the ongoing restoration of edaphic conditions for salt marsh species facing sea level rise: An adaptive management case study in Camargue, France

The Camargue or Rhône delta is a coastal wetland in southern France of which parts formerly devoted to salt production are undergoing a renaturation process. This study assessed a multisensor approach to investigate the link between sediment size distribution, habitat development mapped with Worldview 2, flooding durations estimated with time series of SENTINEL 2 images and elevation modelled with a LIDAR point cloud in former saltworks. A Random Forest classification algorithm was used to map the vegetation distributions of Sarcocornia fruticosa and Arthrocnemum macrostachyum, main representatives of the NATURA 2000 “Mediterranean and thermo-Atlantic halophilous scrubs (Sarcocornetea fruticosi)” habitat on the site. The best habitat map was obtained when considering the species separately. The random forest Out-of-bag errors were 1.43 % for S. fruticosa and 2.18 % for A. macrostachyum. Both species were generally distributed on different elevation and flooding duration zones considering mean values. Flooding duration was estimated with the Water In Wetland index (WIW) based on 15 Sentinel-2 scenes. Two models related to sediment grain size distribution were developed: one predicting the flooding duration and one predicting the halophilous scrub distribution. Maps of flooding duration, sediment grain size distribution and elevation highlighted two main zones in the study area: a western section with coarser sediments, shorter flooding durations and higher elevations under sea influence; an eastern section with finer sediments, longer hydroperiods and lower elevations under a historic river influence. This multidisciplinary approach offers perspectives for using space-based data over large scales to monitor changes in edaphic conditions of coastal areas facing natural and anthropogenic forcings. The results call for further investigations to predict the dynamic distribution of other coastal habitats following climate change impacts, such as sea level rise.

Detrital zircon and tourmaline unravel polycyclic provenance of sedimentary infill of the Cretaceous Tupanciretã formation, southern Brazil

The recognition and evaluation of polycyclic processes in sedimentary units are critical for proper provenance analysis and sedimentary system interpretation. The chemical composition and textural maturity of detrital tourmalines and zircons allow identification of sediment source areas, transport, and deposition. This study investigates the origin and history of post-Gondwanan sediments of the Tupanciretã Formation in southern Brazil, which lacks provenance studies. The Tupanciretã Formation is in a similar setting of the Bauru Supersequence at the uppermost portion of the Paraná Basin. Detrital zircon ages indicate sediment provenance from the Transamazonian, Grenvillian, and Brasiliano orogenic cycles of the Rio Grande do Sul Shield and younger grains (280-128 Ma) record contribution from the Choiyoi and Serra Geral igneous events, with a maximum deposition age of 127 Ma. Detrital tourmaline chemical analyses points to the Sul-riograndense Shield as the ultimate source, with metapelitic, metapsamitic and granitic origins. The predominant degrees of roundness are well rounded to rounded suggest evidence of sediment recycling from sedimentary units of the Paraná Basin, with important aeolian reworking involved. Zircon U–Pb signatures are compatible with the eastern sector of the Botucatu Formation in Rio Grande do Sul as the immediate source and the northeastern Sul-riograndense Shield as the ultimate source. Intermediate sources between the Sul-riograndense Shield and the Tupanciretã Formation were Gondwanan sedimentary units of the Paraná Basin, with possible participation from the Camaquã Basin.

Complex characteristics of suevites at the B. Vanuyta river (Kara astrobleme, Russia)

Research subject. Suevites from the eastern sector of the Kara astrobleme, located in the basin of the Bolshaya Vanuyta river. Aim. To identify the suevitic type and to clarify the facial features of the suevites from the B. Vanuyta River. Materials. Hand-size samples of suevites collecteed in the basins of B. Vanuyta, Anaroga, Kara, and Sopchayu rivers, as well as samples of siltstones collected outside the Kara crater (rivers Halmeryu, Sayakha, Putyu, Anaroga and the creek Lavovyi). The samples were used for preparing polished thin sections and powder specimens for analytical works. Methods. Field observations, optical and electron scanning microscopy, and silicate analysis by the wet chemical method. Results and conclusions. The structural-textural and petrochemical features of the matrix, fragments of impact glasses, and lithoclasts of suevites from the B. Vanuyta river were characterized. The suevite matrix was found to exhibit an intensely sintered character and to be presented by feldspar, quartz, calcite, chlorite, muscovite, glauconite, and titanite. Lithoclasts include siltstones, sandstones, limestones, mudstones, and shales. Vitroclasts are characterized by angular and irregular morphology with different border patterns, and spotted, fluid, and porous textures. The similarity of the chemical composition of siltstone clusters and similar target rocks confirms the genetic relationship and the leading role of this type of target rocks in the formation of the studied suevites. The proximity in the composition of the impact glasses of the studied suevites and the glasses of type I and II suevites indicates the formation of suevite vitroclasts in the river B. Vanuyta by a similar protolith – siltstones and a clay component of the limestones. The matrix lithification character, morphology and nature of the vitroclast outlines indicate that the suevites from the B. Vanuyta river are the rocks of an aerodynamic facies formed under relatively high-temperature conditions, which structurally lie at the lower part of the detrital impactites sequence of the aerodynamic facies. The studied rocks are close to the type I suevites by the composition of the protolith and differ in the conditions of their formation. With the type II suevites, they have similar facies characteristics, but differ in the composition of the target rocks fragments. It is determined that the leading factor in the typification of suevites from the Kara astrobleme is the chemical composition, at the same time, the types can be subdivided more fractionally based on the specifics of the facies environments of their formation.

Geochemical data of the Ediacaran-Cambrian magmatism of Jbel Belkheit and Jbel Bou-Acila as evidence for the Hercynian Cycle Rift-to-Drift events in the Moroccan Central Hercynian Massif

In the eastern sector of the Moroccan Central Hercynian Massif, Ediacaran and Cambrian magmatic rocks outcrop in the anticlines of Jbel Belkheit and Jbel Bou-Acila. These were emplaced between Pan-African deformed-sequences and Lower Palaeozoic levels in two successive volcanic series, separated by confirmed Lower Cambrian limestones: a) a lower series of Ediacaran age composed of felsic and intermediate volcanic rocks (rhyodacites and andesites). The rhyodacites are clearly calc-alkaline in character, comparable to rocks generated in an active margin orogenic context, whereas the andesites are transitional between calc-alkaline and tholeiitic, reflecting a change in the geotectonic context at the end of the Neoproterozoic; and b) an upper series of Cambrian age, composed of anorogenic tholeiitic basalts with massive flows in the bottom and pillow lavas in the top of the sequence. Although structural, petrographic and geochemical data rule out any genetic link between the felsic and the intermediate Ediacaran rocks, a geochemical link between the andesites and Cambrian basalts can be suggested. Both facies are thought to have been generated in an extensional context, although some of the orogenic features of their protolith are still present.In this sense, the Ediacaran andesites would be precursors of the Late Neoproterozoic – Early Cambrian rift rocks, leading to the eventual formation of Cambrian basalts. The latter facies were already emplaced in a clear extensional geodynamic context, and were probably generated by the same source that evolved during progressive crustal extension and thinning. This is confirmed by the evolution of Cambrian basalt morphostructures and geochemical characteristics from: i) massive flow basalts with a geochemical signature of intraplate tholeiites of E-MORB character; to ii) pillow lavas of oceanic tholeiites with a N-MORB character. This transition, therefore, marks the beginning of an oceanization process, which has never been described elsewhere in the Moroccan Cambrian.

Landslide risk assessment and management using hybrid machine learning‐based empirical models

Landslides are a prevalent geologic phenomenon that substantially threatens human life and infrastructure, resulting in considerable loss and destruction. The practice of landslide susceptibility mapping is crucial for the mitigation of risks connected with this natural disaster. This work aims at investigating the influence of varying sample sizes on the precision of landslide susceptibility modelling using a case study conducted in the Alamout basin, Iran. The researchers used a machine learning methodology based on tree algorithms to construct a model for predicting the likelihood of landslides. Additionally, they adopted a multi‐scenario strategy to address the inherent uncertainty associated with the input data. The integration of the naive Bayes tree (NBTree), random forest (RF), logistic model tree (LMT) and J48 algorithms was performed. The modelling process included using 20 predictive parameters across four distinct scenarios. Four models, labelled S1, S2, S3 and S4, were used in this study. These models utilized 25%, 50%, 75% and 100% of the available inventory data. The research presented in this study is distinguished by using a tree‐based methodology for landslide susceptibility modelling and incorporating a multi‐scenario strategy to address the inherent uncertainty associated with the input data. The findings indicated that the augmentation of the sample size improved the precision of the models. The efficacy of using a multi‐scenario strategy in enhancing the dependability of the model is also underscored. Among the 20 input elements used in the modelling process, it was seen that slope angle accounted for the highest relative significance, constituting 25.60% of the overall influence. Following more closely, distance to fault contributed significantly, with a relative importance of 23.40%. Additionally, rainfall and elevation exhibited notable contributions, with relative volumes of 7.91% and 5.50%, respectively. All four landslide models showed adequate learning and forecasting ability throughout the training and testing phases. During the testing phase, the true skill score (TSS) values exhibited a range of 0.631–0.804, while the area under the receiver operating characteristic curve values showed a range of 0.745–0.921. The susceptibility maps indicated that a significant portion of the region exhibits moderate to very high susceptibility zones, with the northern and eastern sectors displaying greater landslide values than the western region. The model's performance showed improvement from S1 to S4 in both the training and testing phases. The performance of the models exhibited the following trend: in scenario 1, the RF model outperformed the J48, LMT and NBTree models; in scenario 2, the RF model surpassed the NBTree and LMT models, while being on par with the J48 model; in scenarios 3 and 4, the RF model showed superior performance compared to the NBTree, J48 and LMT models. Therefore, the RF model proved to be the most effective among the models evaluated. The findings derived from this research have the potential to serve as valuable references for the purposes of land‐use planning and catastrophe risk management.