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Geosciences, Volume 13, Issue 11 (November 2023) – 35 articles

Cover Story (view full-size image): Unveiling northern Los Angeles' subsurface structure, the Basin Amplification Seismic INvestigation (BASIN) project employed a dense nodal seismic array across multiple basins. Sedimentary basin configuration significantly shapes seismic wave dynamics, potentially intensifying ground shaking and hazards during earthquakes. Utilizing 758 nodal seismometers strategically placed along linear transects in the San Bernardino, Chino, and San Gabriel basins, the study applied teleseismic receiver function techniques to expose intricate basin structures with unprecedented detail. BASIN's high lateral resolution revealed significant changes near faults such as San Jacinto, Fontana, Red Hill, and Indian Hill, promising to reshape our understanding of seismic hazards and ground motion dynamics in earthquake-prone regions. View this paper
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14 pages, 1687 KiB  
Article
Linking Disaster Risk Reduction and Climate Change Adaptation through Collaborative Governance: Experience from Urban Flooding in Jakarta
Geosciences 2023, 13(11), 353; https://doi.org/10.3390/geosciences13110353 - 20 Nov 2023
Viewed by 1857
Abstract
This paper examines the challenges of and facilitating strategies for linking disaster risk reduction (DRR) and climate change adaptation (CCA) in addressing urban floods, drawing from Indonesia’s experience. The fragmentation between efforts to implement DRR and CCA leading to unnecessary duplication could increase [...] Read more.
This paper examines the challenges of and facilitating strategies for linking disaster risk reduction (DRR) and climate change adaptation (CCA) in addressing urban floods, drawing from Indonesia’s experience. The fragmentation between efforts to implement DRR and CCA leading to unnecessary duplication could increase confusion at both the community and wider governance levels and reduce the effectiveness of urban flood management. Through the lens of collaborative governance, this paper analyzes the barriers for integrating DRR and CCA and options to better align their practices in the context of a megapolitan city, Jakarta, Indonesia. The key findings of this study confirmed that institutional fragmentation, in concert with inconsistent facilitation and collaboration mechanisms, were the strongest barriers to aligning DRR and CCA action. The absence of accountable leadership was a key impediment for successful partnership-building processes to support political and technical collaboration. Leadership in these contexts plays an important role in (1) developing sustainable relationships, (2) convincing potential stakeholders to collaborate, (3) persuading partners to commit to sharing resources, and (4) agreeing/sharing a common vision of the partnership actions needed to mitigate harm and reduce urban vulnerability. These factors are critically important for reducing the direct and indirect impacts of flooding in Jakarta. Such lessons from Indonesia on linking DRR and CCA offer valuable insights to inform the development of policies and strategies to deal with urban floods for global cities faced with similar challenges. Full article
(This article belongs to the Special Issue Flood Risk Reduction)
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24 pages, 32006 KiB  
Article
Rockfall Susceptibility Assessment and Landscape Evolution of San Nicola Island (Tremiti Islands, Southern Adriatic Sea, Italy)
Geosciences 2023, 13(11), 352; https://doi.org/10.3390/geosciences13110352 - 17 Nov 2023
Cited by 1 | Viewed by 1158
Abstract
San Nicola Island, pertaining to the Tremiti Archipelago (Southern Adriatic Sea, Italy), is widely affected by cliff retreat and gravitational phenomena which severely threaten its monumental historical and natural value. In this study, geomorphological features of the area were derived following a stepwise [...] Read more.
San Nicola Island, pertaining to the Tremiti Archipelago (Southern Adriatic Sea, Italy), is widely affected by cliff retreat and gravitational phenomena which severely threaten its monumental historical and natural value. In this study, geomorphological features of the area were derived following a stepwise approach, combining multitemporal stereoscopic aerial photo interpretations with morphometric analyses and detailed field surveys. A rockfall susceptibility map was created following a heuristic approach based on morphometric and geothematic parameters, accounting for slope, slope aspect, outcropping lithologies, structural discontinuities density, distance from landslide scarps, and presence of anthropic caves. Cliff sectors set on dolomitic limestones feature the highest susceptibility values, especially along the southeastern sector; medium values, instead, are found along the island flanks and along scarps located within the inner sectors; and the lowest values are detected on summit tabular surfaces. The achieved results were compared with historical maps and seismic data derived from local and national archives and catalogues, respectively. These analyses allowed us to define the role played by litho-structural and tectonic features on landslide occurrence and distribution, and their interplay in driving landscape evolution over centuries. Finally, this work represents a valuable scientific tool to support geomorphological studies for landslide hazard assessment and proper territorial planning in any other small insular areas, showing similar geological–geomorphological features and landscape values. Full article
(This article belongs to the Section Natural Hazards)
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20 pages, 9922 KiB  
Article
Calcareous Nannofossils Biostratigraphy of Late Cretaceous–Paleocene Successions from Northern Jordan and Their Implications for Basin Analysis
Geosciences 2023, 13(11), 351; https://doi.org/10.3390/geosciences13110351 - 17 Nov 2023
Viewed by 1598
Abstract
Local geological and tectonic processes have been pivotal in shaping the diverse sedimentation patterns observed in Jordan, forming sub-basins characterized by elevated organic matter content (TOC). This study aims to characterize the Maastrichtian basin, focusing on sedimentation rates using calcareous nannofossils and understanding [...] Read more.
Local geological and tectonic processes have been pivotal in shaping the diverse sedimentation patterns observed in Jordan, forming sub-basins characterized by elevated organic matter content (TOC). This study aims to characterize the Maastrichtian basin, focusing on sedimentation rates using calcareous nannofossils and understanding paleoecological and paleo-oceanic conditions. It offers insights into the paleoenvironmental factors impacting oil shale deposition in the late Maastrichtian–Paleocene period. It employs classical biostratigraphical, semi-quantitative, and statistical methodologies to achieve its objectives of age determination and paleoecological insights. A total of 116 smear slides from two sites were obtained: the first, consisting of WA-1 (23 samples), WA-2 (18 samples), and WA-3 (11 samples), and the second, with 60 samples. Notably, the sites exhibit varying topography. WA-1 and WA-2, situated at lower elevations, have the highest Total Organic Carbon (TOC) levels, while areas with higher elevations in section four are visually identified by a light color. The study revealed varying patterns of calcareous nannofossil richness in the two investigated sites. These patterns were instrumental in defining biozones, with the utilization of marker species such as Lithraphidites quadratus, Micula murus, Micula prinsii, and Cruciplacolithus tenuis. Chronologically, these sections were classified as Maastrichtian–Paleogene, encompassing the following biozones in sequential order: UC-20a, UC-20b, UC-20c, UC-20d, and NP-2. Furthermore, the study identified two hiatus intervals, observed in sections WA-1 and KAS-1. The absence of certain biozones in the analyzed sections suggests that these sections correspond to distinct geological blocks within the basin, underscoring the role of tectonic forces during the deposition period. The sedimentation rate initially commenced at low levels but gradually increased due to topographic alterations. Notably, the biozone UC-20c demonstrated a clear trend toward warming and enhanced nutrient availability. In this context, the abundance and diversity of species were associated with increased continental influx into the sub-basin, resulting in rising nutrient levels and the number of calcareous nannofossils. This study enhances the understanding of the local and global effects such as tectonic and climates of the continuity of basins by deciphering calcareous nannofossil patterns and their correlation with sedimentation factors. Full article
(This article belongs to the Topic Basin Analysis and Modelling)
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7 pages, 193 KiB  
Editorial
Geoheritage and Geotourism Resources: Education, Recreation, Sustainability II
Geosciences 2023, 13(11), 350; https://doi.org/10.3390/geosciences13110350 - 17 Nov 2023
Cited by 2 | Viewed by 1209
Abstract
In recent years, the world’s fascination with the geoenvironment has experienced a remarkable surge [...] Full article
52 pages, 137952 KiB  
Article
Geophysical and Geomatic Methods for the Knowledge, Conservation, and Management of Jordanian Cultural Heritage
Geosciences 2023, 13(11), 349; https://doi.org/10.3390/geosciences13110349 - 15 Nov 2023
Viewed by 1226
Abstract
Jordan has a complex history that has left tangible traces in numerous archaeological sites scattered throughout the country. This unique heritage of inestimable cultural value must be documented, thoroughly researched, and protected in order to prevent its destruction and loss. In this context, [...] Read more.
Jordan has a complex history that has left tangible traces in numerous archaeological sites scattered throughout the country. This unique heritage of inestimable cultural value must be documented, thoroughly researched, and protected in order to prevent its destruction and loss. In this context, knowledge and documentation can be achieved through the application of non-destructive geophysical and geomatic methods. This work represents a synthesis of the results of twenty years of projects carried out at the archaeological sites of Basta, Petra, Um-Hamat (Karak), Umm ar-Rasas, Wu’Ayra, Madaba, and Shawbak. This study enables the exploration of new buried structures in the ground and the documentation of the state of preservation of the structures. It provides an up-to-date overview of Jordan’s rich archaeological heritage and supports restoration projects. Full article
(This article belongs to the Section Geoheritage, Geoparks and Geotourism)
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22 pages, 2093 KiB  
Article
Comparison of Rating Systems for Alberta Rock Slopes, and Assessment of Applicability for Geotechnical Asset Management
Geosciences 2023, 13(11), 348; https://doi.org/10.3390/geosciences13110348 - 14 Nov 2023
Viewed by 1232
Abstract
In 1999, Alberta Transportation and Economic Corridors (TEC) implemented the Geohazard Risk Management Program (GRMP) to identify, assess, monitor, and prioritize the mitigation of risk resulting from geohazard events at specific sites along the provincial highway network. The GRMP was developed to address [...] Read more.
In 1999, Alberta Transportation and Economic Corridors (TEC) implemented the Geohazard Risk Management Program (GRMP) to identify, assess, monitor, and prioritize the mitigation of risk resulting from geohazard events at specific sites along the provincial highway network. The GRMP was developed to address a variety of geohazard types including rockfall hazards that occur at natural and constructed (cut) highway backslopes. An evaluation of various methods for the condition assessment of rockfall geohazards, including TEC’s current GRMP risk rating system, has been completed with the intent of better understanding the suitability of each method as TEC transitions to a formalized GAM program. The GRMP risk rating values for selected rockfall geohazard sites along highway corridors in Alberta were compared to values developed from the results of five established rock mass and rock slope rating systems. The results of this study demonstrate that TEC’s current GRMP risk rating system is a viable tool for the condition assessment and performance monitoring of rockfall geohazards, which could be utilized within a formalized GAM program, further benefitting from years of recorded application in Alberta. Of the other rating systems tested, the rockfall hazard rating system (RHRS) showed a strong correlation with the GRMP risk rating while Q-Slope, the Geological Strength Index (GSI) and Rock Mass Rating (RMR) correlation were marginal but displayed a potential for use as condition assessment tools. The work presented in this paper provides the first evaluation of rock slope rating systems for rockfall hazards along corridors in Alberta, directly comparing them to the slope performance as observed by TEC in a quantitative manner. Full article
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10 pages, 2339 KiB  
Communication
Thermal Conductivity of Frozen and Unfrozen Gas-Saturated Soils
Geosciences 2023, 13(11), 347; https://doi.org/10.3390/geosciences13110347 - 13 Nov 2023
Viewed by 1132
Abstract
Arctic permafrost often contains gas-saturated horizons. The gas component in freezing and frozen soils can exist under different pressures, which are expected to affect their properties and behavior. The effect of pore gas pressure on the thermal conductivity of frozen and unfrozen silt [...] Read more.
Arctic permafrost often contains gas-saturated horizons. The gas component in freezing and frozen soils can exist under different pressures, which are expected to affect their properties and behavior. The effect of pore gas pressure on the thermal conductivity of frozen and unfrozen silt loam saturated with methane or carbon dioxide at pressures below the hydrate formation conditions is observed in the current study. The variable gas pressure and temperature conditions are simulated in a specially designed pressure cell, which allows thermal conductivity measuring in pressurized samples at positive and negative temperatures. The experiments using natural samples collected near the gas emission crater (Yamal Peninsula) show that thermal conductivity is sensitive to pore gas pressure even at high moisture contents. The thermal conductivity of methane-saturated soil becomes 4% and 6% higher in frozen and unfrozen samples, respectively, as the gas pressure increases from 0.1 MPa to 2 MPa. In the case of CO2 saturation, the respective thermal conductivity increase in frozen and unfrozen samples reaches 25% and 15% upon pressure change from 0.1 to 0.9 MPa. The results stimulate further special studies of the effects of gas type and pressure on the thermal properties of closed gas-saturated taliks, of which the pore pressure is increasing during freezing up. Full article
(This article belongs to the Section Cryosphere)
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16 pages, 5037 KiB  
Article
Heterogeneities in the Cohesion of the Deposits of the 2021 Tajogaite Eruption of La Palma (Canary Islands, Spain)
Geosciences 2023, 13(11), 346; https://doi.org/10.3390/geosciences13110346 - 11 Nov 2023
Viewed by 1069
Abstract
The present study analyzes the electrical and thermodynamic properties of the volcanic ash deposits from the recent eruption that started on 19 September 2021 in the Cumbre Vieja area on the island of La Palma. This work compares the analysis of the zeta [...] Read more.
The present study analyzes the electrical and thermodynamic properties of the volcanic ash deposits from the recent eruption that started on 19 September 2021 in the Cumbre Vieja area on the island of La Palma. This work compares the analysis of the zeta potential and the surface free energy components of representative samples of unaltered tephra deposits with samples affected by the fumarolic activity near the emission zone, where sulfurous vapors were present. The results show that fumarolic activity modifies both the zeta potential and the surface free energy components of volcanic ash, decreasing its surface electrical charge and conferring less hydrophilicity on the deposit. Based on this, the interaction energies between ash particles in an aqueous medium have been calculated, in order to analyze the cohesion of the deposit and, where appropriate, its rheological properties, ending with the analysis of the effect produced by different chemical species on the surface charge and free energy of the ashes, and their influence on the cohesion of the deposit. The results confirm an attractive interaction energy between the ash particles and therefore greater stability to the deposit affected by fumarolic activity. Full article
(This article belongs to the Section Geomechanics)
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18 pages, 27945 KiB  
Article
Understanding the Deep Structure of the Essaouira Basin Using Gravity Data: Hydrogeological Inferences for a Semiarid Region in Central-Western Morocco
Geosciences 2023, 13(11), 345; https://doi.org/10.3390/geosciences13110345 - 10 Nov 2023
Viewed by 1452
Abstract
The Essaouira Basin, located in central western Morocco, faces a significant threat of water shortage due to both the substantially reduced rainfall caused by climate change and the continuously increasing demand for this essential resource. Groundwater resources are being increasingly exploited to meet [...] Read more.
The Essaouira Basin, located in central western Morocco, faces a significant threat of water shortage due to both the substantially reduced rainfall caused by climate change and the continuously increasing demand for this essential resource. Groundwater resources are being increasingly exploited to meet the needs of the population, whether for agricultural or domestic purposes. Therefore, it has become necessary to intensify investigations across the entire basin, particularly through indirect methods such as geophysical techniques, to accurately delineate the productive zones. In this context, the present study was undertaken to investigate the deep structure of this basin with the aim of comprehending the functioning of its aquifer system. This study is based on the interpretation of gravity data covering the Essaouira Basin. In addition to their qualitative analysis, these data underwent a methodological approach involving transformations to extract meaningful insights. The observed anomalies were interpreted in terms of (i) thickness variations within the slightly folded sedimentary series of the basin; (ii) Paleozoic basement topography; and (iii) the presence of salt deposits. In fact, among the negative anomalies, some coincide with evaporitic deposits that are known either from the geological outcrops or the seismic surveys carried out in the Essaouira Basin within the framework of petroleum exploration programs, while others coincide with areas of increased thickness of sedimentary sequences. The latter include synclines and basement depressions, where the accumulation of groundwater tends to occur; as a result, they constitute suitable zones for the drilling of water extraction wells. Groundwater flows observed in some existing wells are consistent with this hypothesis. The results of the contact analysis approach implemented within the framework of the study reveals the Essaouira Basin is affected by a fault network whose main direction is parallel to the Atlantic margin (i.e., NNE–SSW). This implies that the extensional tectonic phase responsible for initiating the rifting of the Central Atlantic in the Triassic era has primarily impacted the structural configuration of this basin. This study demonstrates the strong potential of the gravity method as a tool to delineate the deep structure of sedimentary basins and to identify potentially productive groundwater zones. The final results will provide important support to decision makers in sustainable groundwater management, especially in vulnerable areas. Full article
(This article belongs to the Section Hydrogeology)
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18 pages, 4281 KiB  
Article
The Olivine Horizon of the Layered Monchegorsk Pluton (Kola Region, Russia): Additional Magma Injection Based on Integrated Geological and Geochronological Data
Geosciences 2023, 13(11), 344; https://doi.org/10.3390/geosciences13110344 - 09 Nov 2023
Viewed by 1204
Abstract
The paper presents the first SIMS SHRIMP U-Pb data for zircon from an olivine horizon within the Nyud intrusion of the ore-bearing layered Monchegorsk pluton (Monchepluton) in the Kola Region, Russia. A 100–150 m-thick olivine horizon occurs nearly horizontally between the melanocratic and [...] Read more.
The paper presents the first SIMS SHRIMP U-Pb data for zircon from an olivine horizon within the Nyud intrusion of the ore-bearing layered Monchegorsk pluton (Monchepluton) in the Kola Region, Russia. A 100–150 m-thick olivine horizon occurs nearly horizontally between the melanocratic and mesocratic norite of the Nyud intrusion, which disturbs its normal cumulus stratigraphic sequence. In addition, the pyroxene-plagioclase hornfelses are present at the upper contact with the olivine horizon. Twenty-three zircon grains were extracted from the large-volume olivine plagio-orthopyroxenite sample and clustered into two populations. The first population of magmatic zircon (n = 8) has a concordant and weighted average 207Pb/206Pb age of 2484.3 ± 5.6 Ma, which characterizes the formation time of the olivine horizon rocks. This serves as evidence of the olivine horizon that forms as a result of additional magma injection, which does not contradict the geological data. The 207Pb/206Pb age of single-grain zircon is 2414 ± 25 Ma, which indicates the time of postmagmatic transformations. The second population of zircon (n = 16) has a concordant and weighted average U-Pb age of 2700.6 ± 4.6 Ma, which indicates zircon absorption by olivine horizon magma probably from the rocks of the Archean greenstone belt. Full article
(This article belongs to the Section Geochemistry)
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14 pages, 3314 KiB  
Brief Report
Teleseismic P-Wave Attenuation Beneath the Arabian Plate
Geosciences 2023, 13(11), 343; https://doi.org/10.3390/geosciences13110343 - 09 Nov 2023
Viewed by 979
Abstract
In order to prove that the Arabian Plate is a tectonically active region even in its shield areas, we obtained the attenuation structure tp* of the upper mantle beneath the Arabian Plate by applying the spectral inversion method to the newly [...] Read more.
In order to prove that the Arabian Plate is a tectonically active region even in its shield areas, we obtained the attenuation structure tp* of the upper mantle beneath the Arabian Plate by applying the spectral inversion method to the newly established seismic network in Saudi Arabia operated by the Saudi Geological Survey (SGS). The data sets consisted of good quality vertical components of the teleseismic events for more than 4400 spectral ratios. The result showed significant and diverse tp* structures between the eastern and western regions of the Arabian Plate. High tp* was the predominant feature underneath the Arabian Shield (western Arabia) and low tp* within the Arabian Platform (eastern Arabia). The obtained tP* values range from −1.0 s to 1.0 s. The observed high tp* patterns followed a line from north to south through the Arabian Shield along the Red Sea margin. The high tp* distribution closely followed the volcanic region, in particular the Makka–Madina–Nafud Volcanic (MMNV) line. The maximum tp* values were observed in the southern region of the Arabian Shield, at the southern part of the Red Sea, where the African and Arabian Plates diverge. The observed high tp* will be attributed to the previously revealed low-velocity anomaly and thermal activities beneath the Arabian Shield, and it is also correlated with the topography (high elevation) in the region. Full article
(This article belongs to the Section Natural Hazards)
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19 pages, 12955 KiB  
Article
Using Electrical Resistivity Tomography Method to Determine the Inner 3D Geometry and the Main Runoff Directions of the Large Active Landslide of Pie de Cuesta in the Vítor Valley (Peru)
Geosciences 2023, 13(11), 342; https://doi.org/10.3390/geosciences13110342 - 09 Nov 2023
Viewed by 1281
Abstract
Pie de Cuesta is a large landslide with a planar area of 1 km2 located in the Vítor district, in the Arequipa department (Peru), and constitutes an active phenomenon. It belongs to the rotational/translational type, which concerns cases that are very susceptible [...] Read more.
Pie de Cuesta is a large landslide with a planar area of 1 km2 located in the Vítor district, in the Arequipa department (Peru), and constitutes an active phenomenon. It belongs to the rotational/translational type, which concerns cases that are very susceptible to reactivation because any change in the water content or removal of the lower part can lead to a new instability. In this context, a previous geological study has been decisive in recognizing the lithologies present and understanding their behavior when they are saturated. But it is also necessary to know the inner “landslide geometry” in order to gusset a geotechnical diagnosis. The present study shows how the deep electrical profiles (ERT, electrical resistivity tomography method), supported by two Vp seismic refraction tomography lines (SVP), have been used to create a 3D cognitive model that would allow the identification of the inner landslide structure: the 3D rupture surface, the volume of the sliding mass infiltration sectors or fractures, and the preferred runoff directions. Moreover, on large landsides, placing the geophysical profiles is a crucial aspect because it greatly depends on the accessibility of the area and the availability of the physical space required. In our case, we need to extend profiles up to 1100 m long in order to obtain data at greater depths since this landslide is approximately 200 m tall. Based on the geophysical results and geologic information, the 3D final model of the inner structure of this landslide is presented. Additionally, the main runoff water directions and the volume of 90.5 Hm3 of the sliding mass are also estimated. Full article
(This article belongs to the Topic Landslides and Natural Resources)
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17 pages, 15105 KiB  
Article
Differences in Geochemical Signatures and Petrogenesis between the Van Canh and Ben Giang-Que Son Granitic Rocks in the Southern Kontum Massif, Vietnam
Geosciences 2023, 13(11), 341; https://doi.org/10.3390/geosciences13110341 - 07 Nov 2023
Cited by 1 | Viewed by 1156
Abstract
Permian Ben Giang-Que Son and Triassic Van Canh granitic rocks are widely distributed across the southern Kontum Massif, the basement of which consists mainly of metasedimentary rocks. The Ben Giang-Que Son granitic rocks are classified as I- to S-type and ilmenite-series granitic rocks, [...] Read more.
Permian Ben Giang-Que Son and Triassic Van Canh granitic rocks are widely distributed across the southern Kontum Massif, the basement of which consists mainly of metasedimentary rocks. The Ben Giang-Que Son granitic rocks are classified as I- to S-type and ilmenite-series granitic rocks, while the Van Canh granitic rocks are classified as I-type and magnetite-series granitic rocks. Both granitic rock suites exhibit more or less adakitic properties, suggesting that the subduction of the high-temperature Song Ma Ocean crust, part of the Paleo-Tethys Ocean, beneath the Indochina Block produced adakitic magma. It is hypothesized that the differences between the two granitic rock suites were caused by differences in the quantities of incorporated continental crustal materials and carbon or graphite in clastic sedimentary rocks when their adakitic magma intruded into the continental crust. Based on their high initial Sr isotope ratios, the Ben Giang-Que Son granitic rocks evidently incorporated a higher quantity of continental crustal materials compared to the Van Canh granitic rocks, resulting in the former showing the signatures of ilmenite-series and I- to S-type granitic rocks. Consequently, the Ben Giang-Que Son granitic rocks have relatively high A/CNK ratios and high total Al contents in their biotite, whereas the Van Canh granitic rocks have low A/CNK ratios and low total Al contents in their biotite. The intrusion of the Ben Giang-Que Son granitic rocks caused high-temperature metamorphism, which decomposed some of the carbon or graphite in the surrounding continental crustal materials, such as clastic sedimentary rocks. Meanwhile, the Van Canh granitic rocks, which intruded later than the Ben Giang-Que Son granitic rocks, incorporated smaller quantities of carbon or graphite in continental crustal materials, resulting in them retaining the chemical characteristics of adakitic, magnetite-series, and I-type granitic rocks, different from the Ben Giang-Que Son granitic rocks. Full article
(This article belongs to the Section Geochemistry)
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21 pages, 4969 KiB  
Article
Slip Activation Potential of Fractures in the Crystalline Basement Rocks of Kuujjuaq (Nunavik, Canada) to Assess Enhanced Geothermal Systems Development
Geosciences 2023, 13(11), 340; https://doi.org/10.3390/geosciences13110340 - 07 Nov 2023
Viewed by 1422
Abstract
This work presents an estimate of the slip activation potential of existing fractures in a remote northern community located on Canadian Shield rocks for geothermal purposes. To accomplish this objective, we analyzed outcrop analogues and recorded geometrical properties of fractures, namely the strike [...] Read more.
This work presents an estimate of the slip activation potential of existing fractures in a remote northern community located on Canadian Shield rocks for geothermal purposes. To accomplish this objective, we analyzed outcrop analogues and recorded geometrical properties of fractures, namely the strike and dip. Then, we estimated the stress regime in the study area through an empirical approach and performed a probabilistic slip tendency analysis. This allowed us to determine the slip probability of the pre-existing fractures at the current state of stress, the orientation of fractures that are most likely to be activated and the fluid pressures needed for the slip activation of pre-existing fractures, which are key aspects for developing Enhanced Geothermal Systems. The results of this simple, yet effective, analysis suggest that at the current state of stress, the pre-existing natural fractures are relatively stable, and an injection pressure of about 12.5 MPa/km could be required to activate the most optimally oriented fractures to slip. An injection of water at this pressure gradient could open the optimally oriented pre-existing fractures and enhance the permeability of the reservoir for geothermal fluid extraction. The information described in this paper provides a significant contribution to the geothermal research underway in remote northern communities. Full article
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43 pages, 23420 KiB  
Article
The Petrology and Geochemistry of REE-Enriched, Alkaline Volcanic Rocks of Ambitle Island, Feni Island Group, Papua New Guinea
Geosciences 2023, 13(11), 339; https://doi.org/10.3390/geosciences13110339 - 06 Nov 2023
Viewed by 1440
Abstract
Ambitle in the Feni Island Group is located within the NW trending Tabar–Lihir–Tanga–Feni (TLTF) volcanic island chain, Melanesian Arc, northeastern Papua New Guinea. The TLTF chain is renowned for its alkaline magmatism, geothermal activity, copper–gold mineralization, and world-class gold mining. Although its geochemical [...] Read more.
Ambitle in the Feni Island Group is located within the NW trending Tabar–Lihir–Tanga–Feni (TLTF) volcanic island chain, Melanesian Arc, northeastern Papua New Guinea. The TLTF chain is renowned for its alkaline magmatism, geothermal activity, copper–gold mineralization, and world-class gold mining. Although its geochemical patterns indicate island arc signatures (i.e., high LILE and depleted HFSE), TLTF volcanism is not directly related to the older Melanesian Arc subduction system. However, it may have been influenced by source mantle metasomatism linked to the older subduction. The purpose of this study is to (1) present and interpret the petrographic, mineralogical, and geochemical data from Feni within the context of the tectonic evolution of the TLTF and (2) propose a geodynamic, petrogenetic model for the Feni volcanic rocks. The key methodologies used in this study are field mapping and sampling, petrographic analysis using the optical microscope, whole-rock geochemical analysis via XRF and ICP MS, and mineralogical analysis using an electron microprobe. The main rock types sampled in this study include feldspathoid-bearing basalt, trachybasalt, phonotephrite, trachyandesite, and trachydacite. Minerals identified include forsteritic olivine, diopside, augite, labradorite, andesine, anorthitic plagioclase, nepheline, and leucite in the primitive mafic suites, whereas the more evolved intermediate and felsic hypabyssal suites contain amphibole, albite, orthoclase, biotite, and either rare quartz or feldspathoids. Amphibole composition is primarily magnesiohastingsite with minor pargasite formed under polybaric conditions. Accessory minerals include apatite, titanite, and Ti-magnetite. We propose that limestone assimilation followed by fractional crystallization are plausible dominant processes in the geochemical evolution of the Ambitle volcanics. Clinopyroxene fractionation is dominant in the mafic volcanics whereas hornblende fractionation is a major petrologic process within the intermediate suites proven by the enrichment of LREE and depletions in MREE and HREE. Feni magmas are also highly enriched in REEs relative to neighboring arcs. This study is globally significant as alkaline magmas are important sources of Cu, Au, and REE as critical elements for green energy and modern technology. Full article
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27 pages, 7483 KiB  
Article
Soil Erosion and Landslide Susceptibility Mapping in Western Attica, Greece: A Rock Engineering System Approach
Geosciences 2023, 13(11), 338; https://doi.org/10.3390/geosciences13110338 - 03 Nov 2023
Cited by 1 | Viewed by 1652
Abstract
Two of the eight main soil degradation processes with which soils worldwide are confronted are soil erosion and landslides. Specifically, landslides are a major threat in particular areas across Europe, often leading to serious impacts on population, property, and infrastructure. Regarding the abovementioned [...] Read more.
Two of the eight main soil degradation processes with which soils worldwide are confronted are soil erosion and landslides. Specifically, landslides are a major threat in particular areas across Europe, often leading to serious impacts on population, property, and infrastructure. Regarding the abovementioned processes, the case study of the fatal Mandra flash flood (November 2017) in the Attica Region (Greece), which caused 24 deaths, and much infrastructure and building damage, is presented with the intention of assessing the relationship between soil erosion and landslide incidents. Investigations were executed from 2018 to 2022, and their outcomes were taken into consideration by the Technical Authority of the Attica Region. Soil erosion lines were delineated in a GIS and were validated using a previously generated regional Web-GIS landslide susceptibility map. The study presents soil erosion types from the Mandra fatal flash flood event and correlates them with already existing landslide susceptibility analyses for the Attica Region. The produced susceptibility map is a cartographic product on a regional scale (1:100,000) generated via a semiquantitative heuristic methodology named the Rock Engineering System (RES). The way in which both soil erodibility and landslide susceptibility maps were generated and validated could be the basis for proposing modeling approaches that can respond to new developments in European landslide policies. Full article
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21 pages, 7473 KiB  
Article
New Lizard Specimens from the Campanian Wapiti Formation of Alberta, Canada
Geosciences 2023, 13(11), 337; https://doi.org/10.3390/geosciences13110337 - 03 Nov 2023
Viewed by 3766
Abstract
Reported lizard material from the Wapiti Formation (central-western Alberta, Canada) is limited to fragmentary remains of Kleskunsaurus grandeprairiensis and Socognathus unicuspis, a partial dentary attributed to Chamops cf. C. segnis, and a vertebra reportedly comparable to those of the much larger [...] Read more.
Reported lizard material from the Wapiti Formation (central-western Alberta, Canada) is limited to fragmentary remains of Kleskunsaurus grandeprairiensis and Socognathus unicuspis, a partial dentary attributed to Chamops cf. C. segnis, and a vertebra reportedly comparable to those of the much larger lizard Palaeosaniwa canadensis. P. canadensis is a Late Cretaceous North American member of Monstersauria, a Mesozoic and Cenozoic anguimorph group represented today by five species of Heloderma. Here, we document new squamate material from the DC Bonebed locality (Wapiti Unit 3; Campanian), including a right frontal identified as cf. P. canadensis and a taxonomically indeterminate squamate astragalocalcaneum. A partial skeleton from the Two Medicine Formation of Montana provisionally attributed to P. canadensis has a frontal resembling the corresponding element from the DC Bonebed in overall shape, in having narrowly separated facets for the prefrontal and postorbitofrontal, and in bearing osteoderms similar to the DC specimen’s in ornamentation and configuration. The Two Medicine and DC specimens differ from a roughly contemporaneous frontal from southern Alberta referred to the monstersaur Labrodioctes montanensis. The DC specimen confirms the presence of monstersaurian squamates in the Wapiti Formation, representing the northernmost record of any definitive Late Cretaceous monstersaur to date. Full article
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20 pages, 3256 KiB  
Article
Effectiveness of the Geoeducational Assessment Method (GEOAM) in Unveiling Geoeducational Potential: A Case Study of Samos
Geosciences 2023, 13(11), 336; https://doi.org/10.3390/geosciences13110336 - 03 Nov 2023
Cited by 1 | Viewed by 1154
Abstract
This paper explores the efficacy of the geoeducational assessment method (GEOAM) in evaluating the geoeducational potential of geosites. Leveraging a case study involving four geotopes on the island of Samos, Aegean Sea, Greece, this study examines the strengths and limitations of the GEOAM [...] Read more.
This paper explores the efficacy of the geoeducational assessment method (GEOAM) in evaluating the geoeducational potential of geosites. Leveraging a case study involving four geotopes on the island of Samos, Aegean Sea, Greece, this study examines the strengths and limitations of the GEOAM approach, aiming to comprehensively elucidate its efficacy. The assessment outcomes illuminate the vital role of targeted strategies in enhancing the educational and sustainable impact of geosites, thereby fostering geological understanding and responsible environmental engagement. A prominent finding is the urgency to address the gap in foundational geological knowledge, underscored by the need for robust geoeducation programs at schools and the augmented presence of geologists. While acknowledging potential limitations, including subjectivity in scoring and data availability constraints, this study underscores the method’s broader contribution to societal goals. By integrating geoethic principles, GEOAM offers a comprehensive framework aligning with the objectives of geological comprehension and environmentally conscious practices. Full article
(This article belongs to the Section Geoheritage, Geoparks and Geotourism)
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28 pages, 8397 KiB  
Article
Tracking the Route Walked by Missing Persons and Fugitives: A Geoforensics Casework (Italy)
Geosciences 2023, 13(11), 335; https://doi.org/10.3390/geosciences13110335 - 02 Nov 2023
Cited by 1 | Viewed by 993
Abstract
Criminal investigations aiming to track the route walked by missing persons and fugitives (MPFs) usually involve intelligence analysts, military planners, experts in mobile forensics, traditional investigative methods, and sniffer dog handlers. Nonetheless, when MPFs are devoid of any technological device and move in [...] Read more.
Criminal investigations aiming to track the route walked by missing persons and fugitives (MPFs) usually involve intelligence analysts, military planners, experts in mobile forensics, traditional investigative methods, and sniffer dog handlers. Nonetheless, when MPFs are devoid of any technological device and move in uninhabited rural areas devoid of tele cameras and densely covered by vegetation, tracking the route walked by MPFs may be a much more arduous task. In the XVIII century, the expert Georg Popp was able to link a homicide suspect to a sequence of different sites of criminal interest, located in the countryside, by studying the stains of soils found on the footwear and trousers of the suspect. In such complex cases, a very efficient approach for tracking the route walked by MPFs may consist of comparing the geological traces found on the MPFs and their belongings with soils exposed in the event scenes. In particular, the search for peculiar or rare particles and aggregates may strengthen the weight of the geological forensic evidence comparisons. A match of mineralogical, textural, and organic matter data may demonstrate the provenance of the traces from the soil of a specific site, thereby linking the MPFs to the scene of events. Based on the above, the present paper reports geological determinations accomplished for a “mediatic” casework. The results allowed a general high degree of compatibility among traces collected on the MPFs and on the soil from the scene of events to be ascertained. The most significant positive matches, based on the finding of ten peculiar and rare particles and assemblages, allowed the reconstruction of a route about 1.1 km long, as the crow flies, on the event site. Although this procedure was extremely time consuming and available only in a backwards reconstruction linked to the MPFs’ findings, it was of uttermost importance in strengthening the inferences proposed, and for which other methods could not provide any information. Full article
(This article belongs to the Special Issue The State-of-Art Methods and Case Studies in Geoforensics)
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25 pages, 5088 KiB  
Article
Spatiotemporal Variability in the Hydrological Regimes and Water Resources of the Ouham River Basin at Batangafo, Central African Republic
Geosciences 2023, 13(11), 334; https://doi.org/10.3390/geosciences13110334 - 02 Nov 2023
Viewed by 1269
Abstract
This paper examines the effect of rainfall decline on water resources in each sub-basin (Bozoum: 8100 km2 and Bossangoa: 22,800 km2) and at the outlet of Batangafo (43,650 km2) over the 1951–1995 period, due to a lack of [...] Read more.
This paper examines the effect of rainfall decline on water resources in each sub-basin (Bozoum: 8100 km2 and Bossangoa: 22,800 km2) and at the outlet of Batangafo (43,650 km2) over the 1951–1995 period, due to a lack of measurements since 1996. Annual, monthly, and daily series of rainfall and discharges were subjected to statistical tests (rainfall and flow indices, SPI, search for ruptures/breaks, depletion coefficient, and potential groundwater discharge) to present and discuss the rainfall variability impact on the water resources of the whole basin. The average rainfall per sub-basin decreases from the west to the east according to the Ouham river direction: 1423 mm at Bozoum, 1439 mm at Bossangoa, and 1393 mm at Batangafo, the main outlet. The SPI approach provides evidence of a moderate to normal drought in the whole basin in the 1980s, mainly compared to the 1970s. Thus, deficient breaks in the rainfall series of the Ouham Basin at Batangafo were noticed in 1967 (Bossangoa and Batangafo) and 1969 (Bozoum). A declining rainfall of −5% on average tended to have the highest impact on the runoff deficit, from about −30 to −43%. The deficit seems more important from west to east, and is also high over the groundwater in each outlet (−33% at Bozoum, −29% at Bossangoa, and −31% at Batangafo) in the 1986–1995 period, despite rainfall recovery in 1991 having generated a flow increase in 1995 at Bossangoa as well as at Batangafo. At the same time, Chari/Logone at Ndjamena recorded critical discharges in both 1987 (313 m3/s) and 1990 (390 m3/s) before they increased, such as on the Ouham. These results demonstrate the decline in water resources in the Ouham River, and their direct impact on the water level of the Chari River and Lake Chad in the targeted period. Full article
(This article belongs to the Section Hydrogeology)
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27 pages, 8549 KiB  
Article
Application of an Integrated 3D–2D Modeling Approach for Pillar Support Design in a Western US Underground Coal Mine
Geosciences 2023, 13(11), 333; https://doi.org/10.3390/geosciences13110333 - 01 Nov 2023
Viewed by 1222
Abstract
Discontinuum Bonded Block Modeling (BBM) represents a potential tool for support design, as these models can reproduce both the rock fracturing process and the influence of reinforcement on unsupported ground. Despite their strengths, discontinuum models are seldom used for mining design due to [...] Read more.
Discontinuum Bonded Block Modeling (BBM) represents a potential tool for support design, as these models can reproduce both the rock fracturing process and the influence of reinforcement on unsupported ground. Despite their strengths, discontinuum models are seldom used for mining design due to their computationally intensive nature. This study is an application of an integrated 3D continuum–2D discontinuum approach, in which the mine-wide stress distribution process is modeled using a continuum software, and the local deformation behavior in response to a strain path from the continuum model is simulated with a 2D discontinuum software. In June 2017, two multi-point borehole extensometers were installed in a longwall chain pillar to record ground displacements as a function of the longwall face position. The data from one of the extensometers were employed to calibrate a panel-scale FLAC3D model. The boundary conditions along the pillar slice containing the extensometer were extracted from the FLAC3D model and applied to a 2D BBM, and the input parameters were modified to match the extensometer data. The calibrated BBM was able to reproduce the unsupported rib deformation and depth of the fracturing well. Subsequently, a few support schemes were tested to demonstrate how the incorporation of support might affect rib deformation. Full article
(This article belongs to the Section Geomechanics)
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26 pages, 7931 KiB  
Article
Reviewing the Palaeontological and Palaeoenvironmental Heritage of the Monti Pisani Massif (Italy): A Compelling History of Animals, Plants and Climates through Three Geological Eras
Geosciences 2023, 13(11), 332; https://doi.org/10.3390/geosciences13110332 - 30 Oct 2023
Viewed by 2439
Abstract
The Monti Pisani massif (Tuscany, central Italy) is an isolated mountain relief known for its rich geodiversity, including a remarkable palaeontological heritage from the Palaeozoic, Mesozoic and Cenozoic eras. The Palaeozoic record consists of exquisitely preserved plant remains and rarer invertebrates of Permo-Carboniferous [...] Read more.
The Monti Pisani massif (Tuscany, central Italy) is an isolated mountain relief known for its rich geodiversity, including a remarkable palaeontological heritage from the Palaeozoic, Mesozoic and Cenozoic eras. The Palaeozoic record consists of exquisitely preserved plant remains and rarer invertebrates of Permo-Carboniferous age, which testify to extensive rainforests and large swamps that thrived in an alluvial system under a humid, (sub)tropical climate. In addition to invertebrate shells, invertebrate trace fossils and microbial structures, the Mesozoic record features a diverse Middle Triassic tetrapod ichnoassemblage consisting of tracks of lepidosauromorphs, archosaurs (among which are the earliest dinosauromorph fossils of Italy) and nonmammalian therapsids. These vertebrates lived in a subsiding costal setting that stretched across an expanding rift valley under a subarid climate. The Cenozoic record features abundant fossils of terrestrial vertebrates (including spectacular members of the mammalian megafauna) from karst deposits, testifying to the manifold inhabitants of the massif during the glacial and interglacial phases of the Late Pleistocene. Overall, this long-lasting fossil record remarkably demonstrates how much the Earth’s environments have been changing through the Phanerozoic. The outstanding palaeontological heritage of the Monti Pisani area is in need of specific efforts of conservation and valorisation, especially with respect to the many palaeontological sites that punctuate the massif. Full article
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19 pages, 5223 KiB  
Article
Is the Mesochori Fault a Key Structure for Understanding the Earthquake Activity during the 2021 Damasi Earthquakes in Northern Thessaly, Greece?
Geosciences 2023, 13(11), 331; https://doi.org/10.3390/geosciences13110331 - 30 Oct 2023
Viewed by 1422
Abstract
On 3 March 2021, an important seismic sequence started in northern Thessaly, Greece. The Damasi Seismic Sequence (DSS) deformed the western sector of the Tyrnavos Graben, which includes a major blind normal fault and the Titarisios River Graben (TRG). In this contribution, we [...] Read more.
On 3 March 2021, an important seismic sequence started in northern Thessaly, Greece. The Damasi Seismic Sequence (DSS) deformed the western sector of the Tyrnavos Graben, which includes a major blind normal fault and the Titarisios River Graben (TRG). In this contribution, we provide fieldwork observations across the TRG and satellite radar interferometry of the faults controlling the graben. In addition, we provide a map of the active faults exposed in the TRG and palaeoseismological analyses of the Mesochori Fault, which together contribute to unravelling the seismic history of the area. DInSAR provides clear evidence of the Mesochori Fault surface rupture during the main shocks, while our palaeoseismological analyses document a long seismic history of the fault, with a mean recurrence interval of 1.0–1.5 ka and a mean slip per event of ~15 cm for the last four events reactivating the scarp. Quantitative geomorphological analyses based on real-time kinematic (RTK) measurements with global navigation satellite system (GNSS) receivers and data from UAV flight campaigns also provide evidence of postseismic activity across the Mesochori Fault. Based on these results showing that (at least) the Mesochori Fault has been reactivated several times in the latest Quaternary the seismotectonics of the TRG are discussed. Full article
(This article belongs to the Special Issue Active Tectonics and Earthquakes)
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17 pages, 1585 KiB  
Article
Geodetic Applications and Improvement of the X- and L-Method of Deformation Analysis
Geosciences 2023, 13(11), 330; https://doi.org/10.3390/geosciences13110330 - 30 Oct 2023
Viewed by 994
Abstract
Monitoring displacements of the object can be performed using geodetic methods by selecting reference points on the surrounding terrain and points on the object that discretely describe the object’s behavior. The measurements are repeated in several epochs. By analyzing the geodetic network we [...] Read more.
Monitoring displacements of the object can be performed using geodetic methods by selecting reference points on the surrounding terrain and points on the object that discretely describe the object’s behavior. The measurements are repeated in several epochs. By analyzing the geodetic network we can determine the status of a single point, i.e., whether the point has moved or not. The article discusses the testing of congruence, the testing of transformation of a single triangle, and the calculation of other deformation parameters in 2D networks resulting from the changes of points coordinates between two epochs. This is essentially the content of the Munich deformation method presented by W.M. Welsch, which includes the X- and L-method. The article also proposes some corrections to the original Munich approach. Finally, the applicability of the method is shown on a well-known practical example. Full article
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29 pages, 10302 KiB  
Review
Late Quaternary Relative Sea-Level Changes and Vertical GNSS Motions in the Gulf of Corinth: The Asymmetric Localization of Deformation Inside an Active Half-Graben
Geosciences 2023, 13(11), 329; https://doi.org/10.3390/geosciences13110329 - 28 Oct 2023
Viewed by 1332
Abstract
Remains of past sea levels such as tidal notches may provide valuable information for the investigation of relative sea-level changes (RSL) of eustatic/tectonic origin. In this review, we focus on case studies of coastal changes from the Corinth Gulf, where impacts of past [...] Read more.
Remains of past sea levels such as tidal notches may provide valuable information for the investigation of relative sea-level changes (RSL) of eustatic/tectonic origin. In this review, we focus on case studies of coastal changes from the Corinth Gulf, where impacts of past earthquakes can be traced through various indicators. The southern coast has undergone a tectonic uplift during the Holocene, whereas the northern coast has undergone subsidence. The magnitude of RSL fall in the south Corinth Gulf is larger than RSL rise in the north. Exploiting previous measurements and datings, we created a geodatabase regarding the relative sea-level changes of the whole gulf, including geodetic data based on permanent GNSS observations. The combination of geomorphological (long-term) and geodetic (short-term) data is a key advance for this area, which is characterized by fast rates of N-S crustal extension and strong earthquakes. The joint dataset fits the tectonic model of an active half-graben where the hanging wall (northern coast) subsides and the footwall (southern coast) is uplifted. The highest uplift rates (3.5 mm/year) are near Aigion, which indicates an asymmetric localization of deformation inside this active rift. Full article
(This article belongs to the Section Natural Hazards)
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22 pages, 33425 KiB  
Article
Geocryological Structure of a Giant Spring Aufeis Glade at the Anmangynda River (Northeastern Russia)
Geosciences 2023, 13(11), 328; https://doi.org/10.3390/geosciences13110328 - 26 Oct 2023
Viewed by 1199
Abstract
Gigantic aufeis fields serve as indicators of water exchange processes within the permafrost zone and are important in assessing the state of the cryosphere in a changing climate. The Anmangynda aufeis, located in the upstream of the Kolyma River basin, is present in [...] Read more.
Gigantic aufeis fields serve as indicators of water exchange processes within the permafrost zone and are important in assessing the state of the cryosphere in a changing climate. The Anmangynda aufeis, located in the upstream of the Kolyma River basin, is present in the mountainous regions of Northeast Eurasia. Recent decades have witnessed significant changes in aufeis formation patterns, necessitating a comprehensive understanding of cryospheric processes. The objective of the study, conducted in 2021–2022, was to examine the structure of the Anmangynda aufeis and its glade, aiming to understand its genesis and formation processes. The tasks included identifying above- and intra-frozen taliks, mapping groundwater (GW) discharge channels, determining permafrost base depth, and assessing ice thickness distribution. Soundings using ground-penetrating radar (GPR), capacitively coupled electrical resistivity tomography (CCERT), and the transient electromagnetic (TEM) method were employed. GW discharge channels originating from alluvial deposits and extending to the aufeis surface within river channels were identified through GPR and verified through drilling. Deep-seated sources of GW within the bedrock were inferred. CCERT data allowed us to identify large and localized frozen river taliks, from which water is forced onto the ice surface. According to the TEM data, the places of GW outlets spatially coincide with the zones interpreted as faults. Full article
(This article belongs to the Special Issue Mass Transfer and Phase Transformations in Permafrost)
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17 pages, 4724 KiB  
Article
Agent-Based Modeling of Tsunami Evacuation at Figueirinha Beach, Setubal, Portugal
Geosciences 2023, 13(11), 327; https://doi.org/10.3390/geosciences13110327 - 26 Oct 2023
Viewed by 1206
Abstract
Previous tsunami numerical model results show that the 1755 tsunami reached the Figueirinha beach 35 min after the earthquake, resulting in the inundation of the beach, the parking lot, and two sections of the road on the beach. Thus, an effective evacuation plan [...] Read more.
Previous tsunami numerical model results show that the 1755 tsunami reached the Figueirinha beach 35 min after the earthquake, resulting in the inundation of the beach, the parking lot, and two sections of the road on the beach. Thus, an effective evacuation plan for the beach must be identified. However, conducting drills and evacuation exercises is costly and time-consuming. As an alternative, this study develops an agent-based model (ABM) to simulate the evacuation of beach users. The findings from this study reveal that, across the six considered scenarios, it is not feasible to evacuate all beach users in less than 35 min. The results also show there are only two routes available for evacuation—the left and right sides—with the left side offering a shorter evacuation time. However, both evacuation options come with advantages and disadvantages. The results of this study will be disseminated to local stakeholders. Full article
(This article belongs to the Collection Tsunamis: From the Scientific Challenges to the Social Impact)
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22 pages, 11529 KiB  
Article
Influence of Root Reinforcement on Shallow Landslide Distribution: A Case Study in Garfagnana (Northern Tuscany, Italy)
Geosciences 2023, 13(11), 326; https://doi.org/10.3390/geosciences13110326 - 25 Oct 2023
Viewed by 1448
Abstract
In this work, we evaluated the influence of root structure on shallow landslide distribution. Root density measurements were acquired in the field and the corresponding root cohesion was estimated. Data were acquired from 150 hillslope deposit trenches dug in areas either devoid or [...] Read more.
In this work, we evaluated the influence of root structure on shallow landslide distribution. Root density measurements were acquired in the field and the corresponding root cohesion was estimated. Data were acquired from 150 hillslope deposit trenches dug in areas either devoid or affected by shallow landslides within the Garfagnana Valley (northern Tuscany, Italy). Results highlighted a correlation between the root reinforcement and the location of measurement sites. Namely, lower root density was detected within shallow landslides, with respect to neighboring areas. Root area ratio (RAR) data allowed us to estimate root cohesion by the application of the revised version of the Wu and Waldron Model. Then, we propose a new method for the assimilation of the lateral root reinforcement into the infinite slope model and the limit equilibrium approach by introducing the equivalent root cohesion parameter. The results fall within the range of root cohesion values adopted in most of the physically based shallow landslide susceptibility models known in the literature (mean values ranging between ca. 2 and 3 kPa). Moreover, the results are in line with the scientific literature that has demonstrated the link between root mechanical properties, spatial variability of root reinforcement, and shallow landslide locations. Full article
(This article belongs to the Section Natural Hazards)
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21 pages, 5715 KiB  
Article
A Middle Permian Oasis for Vertebrate and Invertebrate Life in a High-Energy Fluvial Palaeoecosystem of Southern Gondwana (Karoo, Republic of South Africa)
Geosciences 2023, 13(11), 325; https://doi.org/10.3390/geosciences13110325 - 25 Oct 2023
Viewed by 1336
Abstract
The Gansfontein palaeosurface (Fraserburg, Karoo, South Africa), which is correlated with the stratigraphic lowermost part of the continental Middle–Upper Permian Teekloof Formation, is revisited. This treasure trove of peculiar and exquisitely preserved sedimentary structures and invertebrate and vertebrate traces serves as a document [...] Read more.
The Gansfontein palaeosurface (Fraserburg, Karoo, South Africa), which is correlated with the stratigraphic lowermost part of the continental Middle–Upper Permian Teekloof Formation, is revisited. This treasure trove of peculiar and exquisitely preserved sedimentary structures and invertebrate and vertebrate traces serves as a document of a set of fluvial paleoenvironments ranging from small ponds to marginal lacustrine and muddy riverine outer banks. It represents an isolated and relatively small “oasis” within the dominating sedimentary environments of the Teekloof Formation characterized by fine and medium-grained siliciclastics related to repeated higher-energy flooding events. The vertebrate traces include abundant therapsid trackways and, locally, tetrapod swimming traces. Tetrapod footprints show a very variable preservation in different areas of the palaeosurface, and it also changed based on the time of impression. Fish trails (Undichna) are relatively common. The invertebrate ichnofauna is comprised of abundant arthropod traces and horizontal burrows; however, the palaeosurface was not intersected by intense bioturbation. The occurrence of this scenario of abundant life reflects complex interaction among different tracemakers with the substrate and is evidence of a relatively quiet palaeoenvironment, which was suddenly submerged and sealed during a flooding event. Sedimentological and ichnological insights from such a palaeosurface, therefore, opens a rare window into Middle Permian ecosystems in southernmost Gondwana. Full article
(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)
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29 pages, 6953 KiB  
Article
Provenance of the Papuan Peninsula (Papua New Guinea): Zircon Inheritance from Miocene–Pliocene Volcanics and Volcaniclastics
Geosciences 2023, 13(11), 324; https://doi.org/10.3390/geosciences13110324 - 25 Oct 2023
Viewed by 1215
Abstract
Plate tectonic reconstructions of Papua New Guinea prior to the late Cenozoic are characterized by a lack of provenance data to constrain the relative origin of the allochthonous terranes. At present, plate tectonic reconstructions of this region infer that the accreted New Guinea [...] Read more.
Plate tectonic reconstructions of Papua New Guinea prior to the late Cenozoic are characterized by a lack of provenance data to constrain the relative origin of the allochthonous terranes. At present, plate tectonic reconstructions of this region infer that the accreted New Guinea terranes at the northern Australian continental margin are likely autochthonous or para-autochthonous in nature. This study presents the results of an investigation into zircons derived from Miocene–Pliocene volcanics and volcaniclastics of the Papuan Peninsula. Results from U-Pb zircon geochronology inform the recent geological history of the Papuan Peninsula, with magmatism active in the late Miocene and early Pliocene, between approximately 9 Ma and 4.5 Ma. More significantly, however, is the recognition of extensive inherited zircon grains within the volcanic and volcaniclastic sequences. These inherited zircon grains are most likely sourced from the Owen Stanley Metamorphics, which form the basement rocks of the Papuan Peninsula. Provenance of the inherited zircon grains imply that the Cretaceous volcaniclastic protolith of the Owen Stanley Metamorphics must have had input from continental detritus, but this cannot be derived from North Queensland, Australia as inferred by current reconstructions. Instead, zircon U-Pb age spectra correlate with probable source regions further to the south, adjacent to the Shoalwater Formation of the Central Queensland margin, and New Caledonia. These findings suggest that late Mesozoic and Cenozoic regional reconstructions of eastern Australia and the Southwest Pacific require major revision and that additional work is undertaken to inform the provenance of such allochthonous terranes. Full article
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