Pub Date : 2024-07-01DOI: 10.17491/jgsi/2024/173946
Monir Modjarrad
In this research, our focus has been on the quantitative calculations of the texture of volcanic rocks. For this purpose, the rocks with acidic to basic and ultrabasic combinations were selected, and the shape, size, and spatial distribution (CSD and SDP) of their phenocrysts were investigated. The results showed that in volcanic rocks, the ratio of nucleation to crystal growth (J/G) was several times higher, and crystal growth per time unit (Gt) was higher in rocks with fewer nuclei. It also turns out that to evaluate the magma mixing, CSD pattern analysis can be instrumental. The spatial distribution of grains in the extrusive rocks is clustered to random, probably due to the high degree of overstepping and under-cooling conditions. The mineral clusters may form before the emplacement of the flow, at depth during the residence time before the eruption flow, or throughout the rise and flow. The importance of these results displays that due to the progress of imaging methods and statistical-numerical work on crystals and textures; it is time that all petrologists from all over the world, along with geochemical work, pay attention to these types of studies to provide a complete petrological work.
{"title":"Numerical Texture Analysis on NW Iran Dacite, Basalt, and Tephraphonolite: Implications to Constrain their Petrogenesis","authors":"Monir Modjarrad","doi":"10.17491/jgsi/2024/173946","DOIUrl":"https://doi.org/10.17491/jgsi/2024/173946","url":null,"abstract":"\u0000 In this research, our focus has been on the quantitative calculations of the texture of volcanic rocks. For this purpose, the rocks with acidic to basic and ultrabasic combinations were selected, and the shape, size, and spatial distribution (CSD and SDP) of their phenocrysts were investigated. The results showed that in volcanic rocks, the ratio of nucleation to crystal growth (J/G) was several times higher, and crystal growth per time unit (Gt) was higher in rocks with fewer nuclei. It also turns out that to evaluate the magma mixing, CSD pattern analysis can be instrumental. The spatial distribution of grains in the extrusive rocks is clustered to random, probably due to the high degree of overstepping and under-cooling conditions. The mineral clusters may form before the emplacement of the flow, at depth during the residence time before the eruption flow, or throughout the rise and flow. The importance of these results displays that due to the progress of imaging methods and statistical-numerical work on crystals and textures; it is time that all petrologists from all over the world, along with geochemical work, pay attention to these types of studies to provide a complete petrological work.","PeriodicalId":50001,"journal":{"name":"Journal of the Geological Society of India","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141706725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.17491/jgsi/2024/173948
B.K. Rastogi, P. Ramancharla
{"title":"A Report on National Symposium on “Natural Hazards & Build Better for Risk Mitigation” and Annual Convention of ISES “Advances in Earthquake Science (AES 2024)”","authors":"B.K. Rastogi, P. Ramancharla","doi":"10.17491/jgsi/2024/173948","DOIUrl":"https://doi.org/10.17491/jgsi/2024/173948","url":null,"abstract":"","PeriodicalId":50001,"journal":{"name":"Journal of the Geological Society of India","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141691485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.17491/jgsi/2024/173934
Kusumita Arora
{"title":"Solar Storms and the Geomagnetic Field","authors":"Kusumita Arora","doi":"10.17491/jgsi/2024/173934","DOIUrl":"https://doi.org/10.17491/jgsi/2024/173934","url":null,"abstract":"","PeriodicalId":50001,"journal":{"name":"Journal of the Geological Society of India","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141702423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.17491/jgsi/2024/173951
L. S. Chamyal
{"title":"Rajendra Kumar Pant (1934-2024)","authors":"L. S. Chamyal","doi":"10.17491/jgsi/2024/173951","DOIUrl":"https://doi.org/10.17491/jgsi/2024/173951","url":null,"abstract":"","PeriodicalId":50001,"journal":{"name":"Journal of the Geological Society of India","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141692066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.17491/jgsi/2024/173938
K. Sivaram, Prantik Mandal, Rahul Biswas, B. Prasad, M. S. Dixith, S. Madhusudhan
We investigate the site characterization and shallow shear velocity profiles from the analysis of the Horizontal to Vertical Spectral ratio (HVSR) around the Hyderabad metropolitan region (HMR), which falls under the southern Indian shield. This work uses both the ambient noise and microearthquake data to compute the HVSR, and additionally the Random Decrement technique to compute the HVSR of extracted Rayleigh waves. This study indicates comparable HVSR curves at each station with the three different datasets, from which we obtain the average dominant frequency (f0) and amplification value (A0). They are further used to calculate the seismic vulnerability index value (Kg). We observe that the value of f0 around the HMR is not fixed, but is varying in the range of 3.4 to 18 Hz, whereas the value of A0 is in the range of 1.7 to 12 approximately and Kg in the range of 0.16 to 1.68 approximately, with an exception of ∼ 33 at VKB (Vikarabad) station, which may be due to a local unconsolidated sub-surface structure. Based on the Diffused Field Assumption (DFA), we invert the average HVSR curves and average dispersion curves of Rayleigh waves, and provide the shallow shear velocity profiles up to 300 m, along with an approximate estimate of VS30 (in upper 30 m depth). The estimated VS30 values vary between 911 to 3143 m/s, falling under the classifications A and B (mostly Hard Rock and Rock type) of National Earthquake Hazards Reduction Program (NEHRP) (BSSC, 2001). However, our study shows some stations with shear velocity inversions at shallow depths within 300 m, indicating layers of low velocity, needing further study. In the absence of detailed near-surface findings, these findings are valuable inputs for geotechnical engineering studies and urban-city planning around the HMR, and emphasizes the effectiveness the HVSR method to determine sub-surface topography and/or unknown soil structures as an economical investigation viability.
{"title":"Site Characterization and Shallow Shear Velocity through HVSR Measurements around the Hyderabad Metropolitan Region, India","authors":"K. Sivaram, Prantik Mandal, Rahul Biswas, B. Prasad, M. S. Dixith, S. Madhusudhan","doi":"10.17491/jgsi/2024/173938","DOIUrl":"https://doi.org/10.17491/jgsi/2024/173938","url":null,"abstract":"\u0000 We investigate the site characterization and shallow shear velocity profiles from the analysis of the Horizontal to Vertical Spectral ratio (HVSR) around the Hyderabad metropolitan region (HMR), which falls under the southern Indian shield. This work uses both the ambient noise and microearthquake data to compute the HVSR, and additionally the Random Decrement technique to compute the HVSR of extracted Rayleigh waves. This study indicates comparable HVSR curves at each station with the three different datasets, from which we obtain the average dominant frequency (f0) and amplification value (A0). They are further used to calculate the seismic vulnerability index value (Kg). We observe that the value of f0 around the HMR is not fixed, but is varying in the range of 3.4 to 18 Hz, whereas the value of A0 is in the range of 1.7 to 12 approximately and Kg in the range of 0.16 to 1.68 approximately, with an exception of ∼ 33 at VKB (Vikarabad) station, which may be due to a local unconsolidated sub-surface structure. Based on the Diffused Field Assumption (DFA), we invert the average HVSR curves and average dispersion curves of Rayleigh waves, and provide the shallow shear velocity profiles up to 300 m, along with an approximate estimate of VS30 (in upper 30 m depth). The estimated VS30 values vary between 911 to 3143 m/s, falling under the classifications A and B (mostly Hard Rock and Rock type) of National Earthquake Hazards Reduction Program (NEHRP) (BSSC, 2001). However, our study shows some stations with shear velocity inversions at shallow depths within 300 m, indicating layers of low velocity, needing further study. In the absence of detailed near-surface findings, these findings are valuable inputs for geotechnical engineering studies and urban-city planning around the HMR, and emphasizes the effectiveness the HVSR method to determine sub-surface topography and/or unknown soil structures as an economical investigation viability.","PeriodicalId":50001,"journal":{"name":"Journal of the Geological Society of India","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141711047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.17491/jgsi/2024/173936
Prasad Raju, B. Boadi, D. D. Wemegah
The orogenic-style gold deposits in the Sefwi greenstone belt are associated with quartz veins and occur along shear zones. Edge detection techniques (i.e., analytic signal, vertical, and tilt derivatives) were employed to delineate regional planar fabrics (e.g., shear zones, faults) using aeromagnetic data. The enhancing techniques aided the delineation of NE-SW striking lineaments associated with the Kenyase-Yamfo, Hwidiem, Ketesso, Bibiani, and Afema shear zones in the study area. These shear zones are within the Sefwi belt and at the contact zones between the belt and the adjacent metamorphosed volcano-sedimentary rocks of the Sunyani-Comoé and Kumasi-Afema basins. Low-displacement N-S to NNE-SSW trends which are oblique to the NE-SW shear zones, were also delineated. The local bend and offset along the NE-SW striking faults created by the cross-cutting N-S to NNE-SSW faults serve as favourable trap zones to focus fluids migrating along these shear zones. Fry analysis of known orogenic gold occurrences in the study areas shows that the NE-SW lineaments, with an azimuth of 40°-50°, are predominant in controlling the distribution of deposits. There is also a significant structural control in the N-S to NNE-SSW direction with azimuths 0°-10° and 10°-20°.
{"title":"Using Edge Detection Techniques on Aeromagnetic Data to Delineate Structures Controlling Orogenic Gold Deposits in the Sefwi Greenstone Belt, Ghana","authors":"Prasad Raju, B. Boadi, D. D. Wemegah","doi":"10.17491/jgsi/2024/173936","DOIUrl":"https://doi.org/10.17491/jgsi/2024/173936","url":null,"abstract":"\u0000 The orogenic-style gold deposits in the Sefwi greenstone belt are associated with quartz veins and occur along shear zones. Edge detection techniques (i.e., analytic signal, vertical, and tilt derivatives) were employed to delineate regional planar fabrics (e.g., shear zones, faults) using aeromagnetic data. The enhancing techniques aided the delineation of NE-SW striking lineaments associated with the Kenyase-Yamfo, Hwidiem, Ketesso, Bibiani, and Afema shear zones in the study area. These shear zones are within the Sefwi belt and at the contact zones between the belt and the adjacent metamorphosed volcano-sedimentary rocks of the Sunyani-Comoé and Kumasi-Afema basins. Low-displacement N-S to NNE-SSW trends which are oblique to the NE-SW shear zones, were also delineated. The local bend and offset along the NE-SW striking faults created by the cross-cutting N-S to NNE-SSW faults serve as favourable trap zones to focus fluids migrating along these shear zones. Fry analysis of known orogenic gold occurrences in the study areas shows that the NE-SW lineaments, with an azimuth of 40°-50°, are predominant in controlling the distribution of deposits. There is also a significant structural control in the N-S to NNE-SSW direction with azimuths 0°-10° and 10°-20°.","PeriodicalId":50001,"journal":{"name":"Journal of the Geological Society of India","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141846216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01DOI: 10.17491/jgsi/2024/173911
Deepak Kumar, Shomya Kumari
Groundwater is an important natural freshwater reserve on which billions of habitants depend for their diverse utilisation. Global water demand has far exceeded the total available water resources which in turn have put a serious concern on food security. India, is one of the largest agricultural user of groundwater in the world where there has been a large scale revolutionary shift from surface water management to a widespread groundwater abstraction. Increased industrialisation, rapid population growth, climate change, changes in the land use and land cover, has influenced the extensive use of groundwater which simultaneously affects the groundwater level. Groundwater drought occurs when this groundwater level falls below the critical level. In the present study, analysis of groundwater drought of the state of Bihar, India, has been conducted using a drought index called Standardized Groundwater Index (SGI) and the spatial and temporal distribution of SGI has been reflected using GIS approach. The rainfall and groundwater data of 38 districts of Bihar from 2002-2019 has been used and the data was divided seasonally into pre- monsoon, monsoon, post- monsoon and winter seasons. Indian Meteorological Department (IMD) norms have been considered for division of seasons. Further, the trend analysis of groundwater level data of all districts of Bihar for all seasons were studied using Mann-Kendall test statistics and Thein Sen’s slope estimator. The results of SGI spatial and temporal distribution showed that districts namely Aurangabad, Gaya, Buxar, Bhojpur, Kishanganj, Katihar, Kaimur, Rohtas, Nawada, Saran Chappra, Siwan, Samastipur, Supaul are prone to the critical groundwater drought condition. The trend analysis results showed that 45% of the districts were showing decline in the groundwater level particularly in pre-monsoon season.
{"title":"Spatial and Temporal Analysis of Standardized Groundwater Index (SGI): A Case Study of Bihar, India","authors":"Deepak Kumar, Shomya Kumari","doi":"10.17491/jgsi/2024/173911","DOIUrl":"https://doi.org/10.17491/jgsi/2024/173911","url":null,"abstract":"\u0000 Groundwater is an important natural freshwater reserve on which billions of habitants depend for their diverse utilisation. Global water demand has far exceeded the total available water resources which in turn have put a serious concern on food security. India, is one of the largest agricultural user of groundwater in the world where there has been a large scale revolutionary shift from surface water management to a widespread groundwater abstraction. Increased industrialisation, rapid population growth, climate change, changes in the land use and land cover, has influenced the extensive use of groundwater which simultaneously affects the groundwater level. Groundwater drought occurs when this groundwater level falls below the critical level. In the present study, analysis of groundwater drought of the state of Bihar, India, has been conducted using a drought index called Standardized Groundwater Index (SGI) and the spatial and temporal distribution of SGI has been reflected using GIS approach. The rainfall and groundwater data of 38 districts of Bihar from 2002-2019 has been used and the data was divided seasonally into pre- monsoon, monsoon, post- monsoon and winter seasons. Indian Meteorological Department (IMD) norms have been considered for division of seasons. Further, the trend analysis of groundwater level data of all districts of Bihar for all seasons were studied using Mann-Kendall test statistics and Thein Sen’s slope estimator. The results of SGI spatial and temporal distribution showed that districts namely Aurangabad, Gaya, Buxar, Bhojpur, Kishanganj, Katihar, Kaimur, Rohtas, Nawada, Saran Chappra, Siwan, Samastipur, Supaul are prone to the critical groundwater drought condition. The trend analysis results showed that 45% of the districts were showing decline in the groundwater level particularly in pre-monsoon season.","PeriodicalId":50001,"journal":{"name":"Journal of the Geological Society of India","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141278417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01DOI: 10.17491/jgsi/2024/173919
Muhammad Riaz, S. Ghazi, Muhammad Waqas
The present work comprehensively highlights the Late Permian Wargal limestone exposed in the western Salt Range, Pakistan. The purpose of this study is to determine its hydrocarbon with the help of sedimentology and sequence stratigraphy. The outcrop data classified the studied formation into nine lithological units in the Nammal Gorge, Gundi, and Lakrakki Nala sections. Our sequence stratigraphic interpretation reveals that the Wargal Limestone consists of four depositional sequences. These sequences consist of regressive system tract and tansgressive system tract that developed during relative sea-level fall and rise, respectively. Based on contents of fossils, quratz grains and matrix, the studied formation can be classified into six microfacies that suggests the deposition of the carbonate facies thrived in inner to middle shelf environment. Moreover, microfacies comprises of numerous diagenetic features that support the potential of hydrocarbon content. In addition, X-ray diffraction analysis (XRD) data suggests that the main composition of the Wargal Limestone is calcite. Consequently, the integrated results of the sedimentology, sequence stratigraphy, and geochemical analysis provide the credible evidences of its significance in exploration industry.
{"title":"Sedimentology and Sequence Stratigraphy of the Late Permian Wargal Limestone: Implication for Reservoir Potential in the Salt Range, Pakistan","authors":"Muhammad Riaz, S. Ghazi, Muhammad Waqas","doi":"10.17491/jgsi/2024/173919","DOIUrl":"https://doi.org/10.17491/jgsi/2024/173919","url":null,"abstract":"\u0000 The present work comprehensively highlights the Late Permian Wargal limestone exposed in the western Salt Range, Pakistan. The purpose of this study is to determine its hydrocarbon with the help of sedimentology and sequence stratigraphy. The outcrop data classified the studied formation into nine lithological units in the Nammal Gorge, Gundi, and Lakrakki Nala sections. Our sequence stratigraphic interpretation reveals that the Wargal Limestone consists of four depositional sequences. These sequences consist of regressive system tract and tansgressive system tract that developed during relative sea-level fall and rise, respectively. Based on contents of fossils, quratz grains and matrix, the studied formation can be classified into six microfacies that suggests the deposition of the carbonate facies thrived in inner to middle shelf environment. Moreover, microfacies comprises of numerous diagenetic features that support the potential of hydrocarbon content. In addition, X-ray diffraction analysis (XRD) data suggests that the main composition of the Wargal Limestone is calcite. Consequently, the integrated results of the sedimentology, sequence stratigraphy, and geochemical analysis provide the credible evidences of its significance in exploration industry.","PeriodicalId":50001,"journal":{"name":"Journal of the Geological Society of India","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141279893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01DOI: 10.17491/jgsi/2024/173912
Subbulakshmi M., Sachikanta Nanda
Flood is the most destructive disaster which causes loss of human life and the economy. Recently Tamil Nadu has been facing floods frequently. Chennai and Cuddalore districts were affected heavily by the 2015 flood. Cuddalore district comes under the lower vellar basin. This research aims to determine the change in land use land cover and rainfall trend of the lower vellar basin and its impact on flood. The Land use land cover map was prepared for the lower vellar basin for a temporal variation of 5 years for 2005, 2010, and 2015 using remote sensing data (Landsat images) and software (Arc GIS and ERDAS). The settlement has increased, and barren Land has reduced. However, there is no significant change in Waterbodies, forests, littoral swamps and plantations. Daily precipitation data of 30 years are collected, and trend analysis is done using Mann-Kendall (MK) method. Out of the 11 rain gauge stations, 4 stations show a positive precipitation trend. The settlement in 2015 was nearly 2% only in the total area, showing a sustainable land use development. Compared to precipitation, land use and land cover change has minimum effect on the flood.
{"title":"Land Use and Land Cover Dynamics and Precipitation Trend of Lower Vellar basin, Tamil Nadu, India and its Impact on 2015 Flood","authors":"Subbulakshmi M., Sachikanta Nanda","doi":"10.17491/jgsi/2024/173912","DOIUrl":"https://doi.org/10.17491/jgsi/2024/173912","url":null,"abstract":"\u0000 Flood is the most destructive disaster which causes loss of human life and the economy. Recently Tamil Nadu has been facing floods frequently. Chennai and Cuddalore districts were affected heavily by the 2015 flood. Cuddalore district comes under the lower vellar basin. This research aims to determine the change in land use land cover and rainfall trend of the lower vellar basin and its impact on flood. The Land use land cover map was prepared for the lower vellar basin for a temporal variation of 5 years for 2005, 2010, and 2015 using remote sensing data (Landsat images) and software (Arc GIS and ERDAS). The settlement has increased, and barren Land has reduced. However, there is no significant change in Waterbodies, forests, littoral swamps and plantations. Daily precipitation data of 30 years are collected, and trend analysis is done using Mann-Kendall (MK) method. Out of the 11 rain gauge stations, 4 stations show a positive precipitation trend. The settlement in 2015 was nearly 2% only in the total area, showing a sustainable land use development. Compared to precipitation, land use and land cover change has minimum effect on the flood.","PeriodicalId":50001,"journal":{"name":"Journal of the Geological Society of India","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141280907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01DOI: 10.17491/jgsi/2024/173918
Rahman Gul, Saad Khan, S. Baig, Sidra Bibi
About 2400 kilometers long Himalayan region hosts thousands of glaciers which covers about 40,000 km2 as per last update in September 2021. Estimation of snout variation positioning, statistical analysis of climate trends, and the Equilibrium Line Altitude (ELA) of most of the glaciers is challenging due to the rough terrain, higher altitudes and scarcity of spatio-temporal field observations. Moreover, without the climatic data and separating contour between glacier’s accumulation and ablation zones, estimation of the net variation in glacier mass loss or gain over a fixed year, leads to ambiguous results. Therefore, a quarterly trend analysis was carried out on climate data (temperature and precipitation ) and river discharge to evaluate the climate pattern in the Astore Basin. Moreover, this study uses the accumulation area ratio, AAR (0.6 ±0.5) (used for high-altitude mountain glaciers), and accumulation area balance ratio, AABR (2.24 ±0.9) with an interval of 0.05 and 0.01 to estimate ELAs, respectively. The results show that the Bazhin glacier retreat (-2.1 km²) as compared to the Chhongpher (-1.1 km²) and Chongra (-1.2 km²) glaciers. A maximum retreat of the snout position of Bazhin glacier was 1595 m , 3260 m in Chhongpher glacier, and 960 m in Chongra glacier. An increase in the ratio of annual AAR from 0.4 to 0.8 results in reductions of the accumulation area of three major glaciers in the study area. We conclude that the largest glaciers (e.g. Bazhin, Chhongpher and Chongra) stretched between lower to higher altitudes are likely to be more vulnerable, due to the highest AAR and AABR values reported between 5000-5600 meters above sea level (masl). However, the ice-lost estimates vary greatly depending on their three-dimensional surfaces.
{"title":"Spatio-temporal Change in the Glaciers of Astore Basin (North-Western Himalaya), between 2016 and 2021 using Sentinel-2 Satellite Data","authors":"Rahman Gul, Saad Khan, S. Baig, Sidra Bibi","doi":"10.17491/jgsi/2024/173918","DOIUrl":"https://doi.org/10.17491/jgsi/2024/173918","url":null,"abstract":"\u0000 About 2400 kilometers long Himalayan region hosts thousands of glaciers which covers about 40,000 km2 as per last update in September 2021. Estimation of snout variation positioning, statistical analysis of climate trends, and the Equilibrium Line Altitude (ELA) of most of the glaciers is challenging due to the rough terrain, higher altitudes and scarcity of spatio-temporal field observations. Moreover, without the climatic data and separating contour between glacier’s accumulation and ablation zones, estimation of the net variation in glacier mass loss or gain over a fixed year, leads to ambiguous results. Therefore, a quarterly trend analysis was carried out on climate data (temperature and precipitation ) and river discharge to evaluate the climate pattern in the Astore Basin. Moreover, this study uses the accumulation area ratio, AAR (0.6 ±0.5) (used for high-altitude mountain glaciers), and accumulation area balance ratio, AABR (2.24 ±0.9) with an interval of 0.05 and 0.01 to estimate ELAs, respectively. The results show that the Bazhin glacier retreat (-2.1 km²) as compared to the Chhongpher (-1.1 km²) and Chongra (-1.2 km²) glaciers. A maximum retreat of the snout position of Bazhin glacier was 1595 m , 3260 m in Chhongpher glacier, and 960 m in Chongra glacier. An increase in the ratio of annual AAR from 0.4 to 0.8 results in reductions of the accumulation area of three major glaciers in the study area. We conclude that the largest glaciers (e.g. Bazhin, Chhongpher and Chongra) stretched between lower to higher altitudes are likely to be more vulnerable, due to the highest AAR and AABR values reported between 5000-5600 meters above sea level (masl). However, the ice-lost estimates vary greatly depending on their three-dimensional surfaces.","PeriodicalId":50001,"journal":{"name":"Journal of the Geological Society of India","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141281170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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