Regolith thickness is considered as a contributing factor for the occurrence of landslides.Although, mostly it is ignored because of complex nature and as it requires more time and resources for investigation. This st...Regolith thickness is considered as a contributing factor for the occurrence of landslides.Although, mostly it is ignored because of complex nature and as it requires more time and resources for investigation. This study aimed to appraise the role of regolith thickness on landslide distribution in the Muzaffarabad and surrounding areas, NW Himalayas.For this purpose regolith thickness samples were evenly collected from all the lithological units at representative sites within different slope and elevation classes in the field. Topographic attributes(slope, aspect, drainage, Topographic Wetness Index,elevation and curvature) were derived from the Digital Elevation Model(DEM)(12.5 m resolution).Arc GIS Model Builder was used to develop the regolith thickness model. Stepwise regression technique was used to explore the spatial variation of regolith thickness using topographic attributes and lithological units. The derived model explains about 88% regolith thickness variation. The model was validated and shows good agreement(70%) between observed and predicted values. Subsequently, the derived regolith model was used to understand the relationship between regolith thickness and landslide distribution. The analysis shows that most of the landslides were located within 1-5 m regolith thickness. However, landslide concentration is highest within 5-10 m regolith thickness, which shows that regolith thickness played a significant role for the occurrence of landslide in the studied area.展开更多
The Eocene Kuldana Formation(KF)in the Yadgar area of Pakistan,comprises a diverse range of sedimentary facies,including variegated red beds of shales,mudstones,and sandstones,as well as interbedded limestone and marl...The Eocene Kuldana Formation(KF)in the Yadgar area of Pakistan,comprises a diverse range of sedimentary facies,including variegated red beds of shales,mudstones,and sandstones,as well as interbedded limestone and marl.In this study,we conducted an integrated micropaleontological,sedimentological,mineralogical,and geochemical investigation to determine the depositional setting,biochronology,provenance,and paleoclimate of the KF.The study identified six lithofacies and six microfacies,which indicate a variety of environments ranging from floodplains and channels to the margins and shallow marine settings.The nannofossil biostratigraphy places the KF in the Early Eocene,more precisely the NP10 zone(Ypresian),and the fossil zone of benthic foraminifera classifies the study section as the Shallow Benthic Zone SBZ-8(Middle Ilerdian 2).In terms of petrography,the KF sandstone was classified as litharenite and feldspathic litharenite,while the QtFL diagram suggests a recycled orogen.Geochemical proxies indicate an oxidizing environment,a high-to-low regular sedimentation rate,moderate-to-intense chemical weathering in the source region,and a warm-humid to dry climate during the deposition of KF.Overall,the findings suggest that the deposition of KF marks the end of Neo-Tethys due to the Early Eocene Indian–Kohistan collision and that the uplifting of the Himalayas provided the source for the deposition of KF in the foreland basin.The study provides new insights into the depositional environment,biochronology,provenance,and paleoclimate of KF,and highlights the potential for red beds as reliable indicators of oxygenation levels in proximity to mineral deposits.展开更多
文摘Regolith thickness is considered as a contributing factor for the occurrence of landslides.Although, mostly it is ignored because of complex nature and as it requires more time and resources for investigation. This study aimed to appraise the role of regolith thickness on landslide distribution in the Muzaffarabad and surrounding areas, NW Himalayas.For this purpose regolith thickness samples were evenly collected from all the lithological units at representative sites within different slope and elevation classes in the field. Topographic attributes(slope, aspect, drainage, Topographic Wetness Index,elevation and curvature) were derived from the Digital Elevation Model(DEM)(12.5 m resolution).Arc GIS Model Builder was used to develop the regolith thickness model. Stepwise regression technique was used to explore the spatial variation of regolith thickness using topographic attributes and lithological units. The derived model explains about 88% regolith thickness variation. The model was validated and shows good agreement(70%) between observed and predicted values. Subsequently, the derived regolith model was used to understand the relationship between regolith thickness and landslide distribution. The analysis shows that most of the landslides were located within 1-5 m regolith thickness. However, landslide concentration is highest within 5-10 m regolith thickness, which shows that regolith thickness played a significant role for the occurrence of landslide in the studied area.
文摘The Eocene Kuldana Formation(KF)in the Yadgar area of Pakistan,comprises a diverse range of sedimentary facies,including variegated red beds of shales,mudstones,and sandstones,as well as interbedded limestone and marl.In this study,we conducted an integrated micropaleontological,sedimentological,mineralogical,and geochemical investigation to determine the depositional setting,biochronology,provenance,and paleoclimate of the KF.The study identified six lithofacies and six microfacies,which indicate a variety of environments ranging from floodplains and channels to the margins and shallow marine settings.The nannofossil biostratigraphy places the KF in the Early Eocene,more precisely the NP10 zone(Ypresian),and the fossil zone of benthic foraminifera classifies the study section as the Shallow Benthic Zone SBZ-8(Middle Ilerdian 2).In terms of petrography,the KF sandstone was classified as litharenite and feldspathic litharenite,while the QtFL diagram suggests a recycled orogen.Geochemical proxies indicate an oxidizing environment,a high-to-low regular sedimentation rate,moderate-to-intense chemical weathering in the source region,and a warm-humid to dry climate during the deposition of KF.Overall,the findings suggest that the deposition of KF marks the end of Neo-Tethys due to the Early Eocene Indian–Kohistan collision and that the uplifting of the Himalayas provided the source for the deposition of KF in the foreland basin.The study provides new insights into the depositional environment,biochronology,provenance,and paleoclimate of KF,and highlights the potential for red beds as reliable indicators of oxygenation levels in proximity to mineral deposits.
