Pub Date : 2023-11-14DOI: 10.3390/geosciences13110348
Taylor Del Gerhard Wollenberg-Barron, Renato Macciotta Pulisci, Chris Gräpel, Kristen Tappenden, Roger Skirrow
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.
{"title":"Comparison of Rating Systems for Alberta Rock Slopes, and Assessment of Applicability for Geotechnical Asset Management","authors":"Taylor Del Gerhard Wollenberg-Barron, Renato Macciotta Pulisci, Chris Gräpel, Kristen Tappenden, Roger Skirrow","doi":"10.3390/geosciences13110348","DOIUrl":"https://doi.org/10.3390/geosciences13110348","url":null,"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 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.","PeriodicalId":38189,"journal":{"name":"Geosciences (Switzerland)","volume":"18 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134954152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-13DOI: 10.3390/geosciences13110347
Evgeny Chuvilin, Dinara Davletshina, Boris Bukhanov, Sergey Grebenkin
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.
{"title":"Thermal Conductivity of Frozen and Unfrozen Gas-Saturated Soils","authors":"Evgeny Chuvilin, Dinara Davletshina, Boris Bukhanov, Sergey Grebenkin","doi":"10.3390/geosciences13110347","DOIUrl":"https://doi.org/10.3390/geosciences13110347","url":null,"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 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.","PeriodicalId":38189,"journal":{"name":"Geosciences (Switzerland)","volume":"15 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136346698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-11DOI: 10.3390/geosciences13110346
Alfonso Ontiveros-Ortega, José A. Moleón-Baca, Raúl Huertas Mesa, Isabel Abad, Mario Sánchez-Gómez
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.
{"title":"Heterogeneities in the Cohesion of the Deposits of the 2021 Tajogaite Eruption of La Palma (Canary Islands, Spain)","authors":"Alfonso Ontiveros-Ortega, José A. Moleón-Baca, Raúl Huertas Mesa, Isabel Abad, Mario Sánchez-Gómez","doi":"10.3390/geosciences13110346","DOIUrl":"https://doi.org/10.3390/geosciences13110346","url":null,"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 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.","PeriodicalId":38189,"journal":{"name":"Geosciences (Switzerland)","volume":"33 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135086740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-10DOI: 10.3390/geosciences13110345
Abdellah Khouz, Mohammed Jaffal, Jorge Trindade, Blaid Bougadir, Fatima El Bchari, Azzouz Kchikach, Mustapha El Ghorfi, Hassan Ibouh, Mourad Jadoud, Omar Kadiri, Ahmed Manar
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.
{"title":"Understanding the Deep Structure of the Essaouira Basin Using Gravity Data: Hydrogeological Inferences for a Semiarid Region in Central-Western Morocco","authors":"Abdellah Khouz, Mohammed Jaffal, Jorge Trindade, Blaid Bougadir, Fatima El Bchari, Azzouz Kchikach, Mustapha El Ghorfi, Hassan Ibouh, Mourad Jadoud, Omar Kadiri, Ahmed Manar","doi":"10.3390/geosciences13110345","DOIUrl":"https://doi.org/10.3390/geosciences13110345","url":null,"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 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.","PeriodicalId":38189,"journal":{"name":"Geosciences (Switzerland)","volume":"1 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135186033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.3390/geosciences13110343
Talal Merghelani, Jun Kawahara, Kaoru Miyashita, Hani Zahran
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.
{"title":"Teleseismic P-Wave Attenuation Beneath the Arabian Plate","authors":"Talal Merghelani, Jun Kawahara, Kaoru Miyashita, Hani Zahran","doi":"10.3390/geosciences13110343","DOIUrl":"https://doi.org/10.3390/geosciences13110343","url":null,"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 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.","PeriodicalId":38189,"journal":{"name":"Geosciences (Switzerland)","volume":" 22","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135292252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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.
Pie de Cuesta是一个平面面积为1平方公里的大型滑坡，位于秘鲁阿雷基帕省Vítor地区，是一个活跃的现象。它属于旋转/平移类型，这涉及到非常容易再活化的情况，因为含水量的任何变化或下部的去除都可能导致新的不稳定性。在这种情况下，以前的地质研究在识别现有岩性和了解它们饱和时的行为方面具有决定性作用。但为了进行岩土诊断，还需要了解内部的“滑坡几何”。本研究展示了深部电剖面(ERT，电阻率层析成像方法)如何在两条Vp地震折射层析成像线(SVP)的支持下，用于创建三维认知模型，该模型将允许识别内部滑坡结构:三维破裂面，滑动体渗透区域或裂缝的体积，以及首选径流方向。此外，在大型陆地上，放置地球物理剖面是一个至关重要的方面，因为它在很大程度上取决于该地区的可达性和所需物理空间的可用性。在我们的案例中，我们需要将剖面扩展到1100米长，以便在更深的深度获得数据，因为这个滑坡大约有200米高。根据地球物理结果和地质信息，建立了该滑坡内部结构的三维最终模型。此外，还估算了主要径流方向和滑坡体的90.5 Hm3体积。
{"title":"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)","authors":"Yasmine Huayllazo, Rosmery Infa, Jorge Soto, Krover Lazarte, Joseph Huanca, Yovana Alvarez, Teresa Teixidó","doi":"10.3390/geosciences13110342","DOIUrl":"https://doi.org/10.3390/geosciences13110342","url":null,"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 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.","PeriodicalId":38189,"journal":{"name":"Geosciences (Switzerland)","volume":" 30","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135242123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.3390/geosciences13110344
Victor Chashchin, Sergey Sergeev
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.
{"title":"The Olivine Horizon of the Layered Monchegorsk Pluton (Kola Region, Russia): Additional Magma Injection Based on Integrated Geological and Geochronological Data","authors":"Victor Chashchin, Sergey Sergeev","doi":"10.3390/geosciences13110344","DOIUrl":"https://doi.org/10.3390/geosciences13110344","url":null,"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 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.","PeriodicalId":38189,"journal":{"name":"Geosciences (Switzerland)","volume":" 22","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135292517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-07DOI: 10.3390/geosciences13110341
Etsuo Uchida, Ko Yonezu, Takumi Yokokura, Nasuka Mori
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.
二叠系本江雀孙和三叠系Van Canh花岗岩广泛分布于孔图姆地块南部，基底以变质沉积岩为主。本江-阙山花岗岩可划分为I ~ s型和钛铁矿系列花岗岩，凡仓花岗岩可划分为I型和磁铁矿系列花岗岩。推测这两个花岗质岩组的差异是由于大陆地壳物质的掺入量和碎屑沉积岩中碳或石墨含量的差异造成的，当它们的埃达克质岩浆侵入大陆地壳时。本江—雀孙花岗岩具有较高的初始Sr同位素特征，与Van Canh花岗岩相比，本江—雀孙花岗岩明显含有较多的大陆地壳物质，具有钛铁矿系和I—s型花岗岩的特征。因此，本江—雀孙花岗岩具有较高的A/CNK比值和较高的黑云母中总Al含量，而范灿花岗岩具有较低的A/CNK比值和较低的黑云母中总Al含量。本江—阙孙花岗岩的侵入引起了高温变质作用，分解了周围陆相地壳物质(如碎屑沉积岩)中的部分碳或石墨。与此同时，Van Canh花岗岩体侵入时间晚于Ben jiang - que Son花岗岩体，其大陆地壳物质中碳或石墨的含量较低，与Ben jiang - que Son花岗岩体不同，保留了绿质、磁铁矿系列和i型花岗岩体的化学特征。
{"title":"Differences in Geochemical Signatures and Petrogenesis between the Van Canh and Ben Giang-Que Son Granitic Rocks in the Southern Kontum Massif, Vietnam","authors":"Etsuo Uchida, Ko Yonezu, Takumi Yokokura, Nasuka Mori","doi":"10.3390/geosciences13110341","DOIUrl":"https://doi.org/10.3390/geosciences13110341","url":null,"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, 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.","PeriodicalId":38189,"journal":{"name":"Geosciences (Switzerland)","volume":"126 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135539311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-07DOI: 10.3390/geosciences13110340
Mafalda M. Miranda, Ali Yaghoubi, Jasmin Raymond, Andrew Wigston, Maurice B. Dusseault
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.
{"title":"Slip Activation Potential of Fractures in the Crystalline Basement Rocks of Kuujjuaq (Nunavik, Canada) to Assess Enhanced Geothermal Systems Development","authors":"Mafalda M. Miranda, Ali Yaghoubi, Jasmin Raymond, Andrew Wigston, Maurice B. Dusseault","doi":"10.3390/geosciences13110340","DOIUrl":"https://doi.org/10.3390/geosciences13110340","url":null,"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 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.","PeriodicalId":38189,"journal":{"name":"Geosciences (Switzerland)","volume":"145 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135480070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-06DOI: 10.3390/geosciences13110339
Olive L. Ponyalou, Michael G. Petterson, Joseph O. Espi
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.
{"title":"The Petrology and Geochemistry of REE-Enriched, Alkaline Volcanic Rocks of Ambitle Island, Feni Island Group, Papua New Guinea","authors":"Olive L. Ponyalou, Michael G. Petterson, Joseph O. Espi","doi":"10.3390/geosciences13110339","DOIUrl":"https://doi.org/10.3390/geosciences13110339","url":null,"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 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.","PeriodicalId":38189,"journal":{"name":"Geosciences (Switzerland)","volume":"5 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135635048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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