Pub Date : 2022-09-08DOI: 10.15446/esrj.v26n2.68391
Shuheng Li, W. Guo, Na Gao
Numerous lakes formed in the area where the Huai River and the Grand Canal converged during the historical period, and it played a substantial role in the evolution of the regional environment. Gaoyou Lake is a vital detention reservoir in the lower reaches of the Huai River. Variations in hydrology and basin-wide environmental changes were analyzed based on pollen assemblages, grain size data, and lithology from sediment cores collected at Gaoyou Lake. This study focused on variations in the hydrodynamic processes of Gaoyou Lake that were responses to changes in climate, regio- nal hydrological events, and human activity. The high percentages of pollen from terrestrial herbs and results of prin- cipal component analysis suggested that the environment of eastern China was arid from AD 900 to 1300 and that this corresponded to the dry conditions of the Medieval Climate Anomaly. The subsequent period between AD 1300 and 1650 was more humid, as revealed by an increase in aquatic pollen and a decrease in grain size. A rise in xerophytic herb taxa (particularly Artemisia and Chenopodioideae) indicated that the climate became arid again from AD 1650 to 1850, during the Little Ice Age. The modern period (AD 1850 onwards) was characterized by another increase in moisture, as reflected by a decrease in herb pollen and grain sizes. The shifts in the course of the Yellow River in AD 1194 and AD 1855 were recorded by abrupt changes in lithology, sediment characteristics, and the percentages of alien pollen taxa. Intense human impacts were demonstrated by cereal-type pollen and an increase in pollen of other cultivated plants such as Cruciferae and Poaceae. This study provides a foundation for further analysis of the dynamic mechanisms between lake development, climate change, and the effects of significant river changes.
{"title":"Climatic and hydrological changes in Gaoyou Lake, eastern China over the last millennium, inferred from pollen and grain size records","authors":"Shuheng Li, W. Guo, Na Gao","doi":"10.15446/esrj.v26n2.68391","DOIUrl":"https://doi.org/10.15446/esrj.v26n2.68391","url":null,"abstract":"\u0000\u0000\u0000\u0000Numerous lakes formed in the area where the Huai River and the Grand Canal converged during the historical period, and it played a substantial role in the evolution of the regional environment. Gaoyou Lake is a vital detention reservoir in the lower reaches of the Huai River. Variations in hydrology and basin-wide environmental changes were analyzed based on pollen assemblages, grain size data, and lithology from sediment cores collected at Gaoyou Lake. This study focused on variations in the hydrodynamic processes of Gaoyou Lake that were responses to changes in climate, regio- nal hydrological events, and human activity. The high percentages of pollen from terrestrial herbs and results of prin- cipal component analysis suggested that the environment of eastern China was arid from AD 900 to 1300 and that this corresponded to the dry conditions of the Medieval Climate Anomaly. The subsequent period between AD 1300 and 1650 was more humid, as revealed by an increase in aquatic pollen and a decrease in grain size. A rise in xerophytic herb taxa (particularly Artemisia and Chenopodioideae) indicated that the climate became arid again from AD 1650 to 1850, during the Little Ice Age. The modern period (AD 1850 onwards) was characterized by another increase in moisture, as reflected by a decrease in herb pollen and grain sizes. The shifts in the course of the Yellow River in AD 1194 and AD 1855 were recorded by abrupt changes in lithology, sediment characteristics, and the percentages of alien pollen taxa. Intense human impacts were demonstrated by cereal-type pollen and an increase in pollen of other cultivated plants such as Cruciferae and Poaceae. This study provides a foundation for further analysis of the dynamic mechanisms between lake development, climate change, and the effects of significant river changes.\u0000\u0000\u0000\u0000","PeriodicalId":11456,"journal":{"name":"Earth Sciences Research Journal","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45508315","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 : 2022-09-08DOI: 10.15446/esrj.v26n2.97735
Ángel Cibeira Urtiaga, M. Berrocoso, B. Rosado, A. Pazos
The advent of GPS provided a new way of measuring surface displacements due to earthquakes by deploying GPS networks within active seismic areas. Japan is located in the confluence of several tectonic plates, hence its seismicity. In order to surveille this activity, one of wider GPS network in the world was deployed, i.e., GEONET. By processing data from 93 GEONET reference stations, we analyze the 2011 Tohoku-Oki earthquake using PPP strategy. We studied the time series during the event setting up a threshold value at we consider the time series are being altered by the earthquake. We also identified the time after the occurrence when the maximum displacements happen. With the study of these two parameters, we aim to show their different behavior as the main shock propagates along the Japan islands, with a focus on a better understanding of the earthquake and its propagation. To achieving this, a least square adjustment method was used to relate epicentral distance to topocentric displacements and the time of detection to epicentral distance. The results show an exponential behavior of the distance-displacement regression versus a linear behavior of the distance-time regression. Besides, we use the former linear regression to calculate and approximation of the velocity of the shock waves.
{"title":"Detection and study of a high magnitude seismic event from GPS data: Case study of the 2011 Tohoku-Oki earthquake","authors":"Ángel Cibeira Urtiaga, M. Berrocoso, B. Rosado, A. Pazos","doi":"10.15446/esrj.v26n2.97735","DOIUrl":"https://doi.org/10.15446/esrj.v26n2.97735","url":null,"abstract":"\u0000\u0000\u0000The advent of GPS provided a new way of measuring surface displacements due to earthquakes by deploying GPS networks within active seismic areas. Japan is located in the confluence of several tectonic plates, hence its seismicity. In order to surveille this activity, one of wider GPS network in the world was deployed, i.e., GEONET. By processing data from 93 GEONET reference stations, we analyze the 2011 Tohoku-Oki earthquake using PPP strategy. We studied the time series during the event setting up a threshold value at we consider the time series are being altered by the earthquake. We also identified the time after the occurrence when the maximum displacements happen. With the study of these two parameters, we aim to show their different behavior as the main shock propagates along the Japan islands, with a focus on a better understanding of the earthquake and its propagation. To achieving this, a least square adjustment method was used to relate epicentral distance to topocentric displacements and the time of detection to epicentral distance. The results show an exponential behavior of the distance-displacement regression versus a linear behavior of the distance-time regression. Besides, we use the former linear regression to calculate and approximation of the velocity of the shock waves.\u0000\u0000\u0000","PeriodicalId":11456,"journal":{"name":"Earth Sciences Research Journal","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47831671","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 : 2022-05-11DOI: 10.15446/esrj.v26n1.76187
Zhongyu Wang, H. Zhang, Xing He, Q. Jiang, W. Xu, W. Tian
In this research, the vegetation height and a concept of relative submergence are adapted to experimentally investigate the effects of rigid submerged vegetation on flow structure. The results reveal that the relative submergence presents decreasing trend along the submerged vegetation section and the average relative submergence follows a power functional decreasing relationship regarding to the increase of vegetation height. After the exit of vegetation block, the water depths for the vegetated cases resume to the level and trend of the case without vegetation. The differences between the maximum and minimum water depths for the submerged cases follow a linear relationship with vegetation height and a negative power functional relationship with the average relative submergence, with which, the raised water depths due to rigid submerged vegetation can be predicted under similar hydraulic and vegetation conditions to the present research. Due to the retardance of vegetation block, the differences between the maximum and minimum flow velocities increase with the vegetation height as the maximum values change slightly and the minimum values decrease continuously. The findings of the research may improve the comprehensive understandings of open channel hydraulic behaviors affected by rigid submerged vegetation and give some guidance to the river ecological restorations.
{"title":"Effects of vegetation height and relative submergence for rigid submerged vegetation on flow structure in open channel","authors":"Zhongyu Wang, H. Zhang, Xing He, Q. Jiang, W. Xu, W. Tian","doi":"10.15446/esrj.v26n1.76187","DOIUrl":"https://doi.org/10.15446/esrj.v26n1.76187","url":null,"abstract":"In this research, the vegetation height and a concept of relative submergence are adapted to experimentally investigate the effects of rigid submerged vegetation on flow structure. The results reveal that the relative submergence presents decreasing trend along the submerged vegetation section and the average relative submergence follows a power functional decreasing relationship regarding to the increase of vegetation height. After the exit of vegetation block, the water depths for the vegetated cases resume to the level and trend of the case without vegetation. The differences between the maximum and minimum water depths for the submerged cases follow a linear relationship with vegetation height and a negative power functional relationship with the average relative submergence, with which, the raised water depths due to rigid submerged vegetation can be predicted under similar hydraulic and vegetation conditions to the present research. Due to the retardance of vegetation block, the differences between the maximum and minimum flow velocities increase with the vegetation height as the maximum values change slightly and the minimum values decrease continuously. The findings of the research may improve the comprehensive understandings of open channel hydraulic behaviors affected by rigid submerged vegetation and give some guidance to the river ecological restorations.","PeriodicalId":11456,"journal":{"name":"Earth Sciences Research Journal","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41858036","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 : 2022-05-11DOI: 10.15446/esrj.v26n1.87003
N. Tunalioglu, Cem Altuntas
This study aims to estimate effective reflector heights and height differences using the basic geometrical principle of multipath theory by controlling the signal quality for estimations. The geometry of the reflecting signal allows computing the effective reflector height, which is extracted from where the signal reflects on the ground and arrives at the GPS antenna phase center. To achieve that, an experimental case with two stations was conducted in the snow-free environment and GPS receivers were mounted on reflectors, which allowed to measure daily in-situ reflector heights and artificial decrement variations. The reflections from the roof surface were tracked with the first-Fresnel zones. To validate the estimated reflector heights in a controlled test environment, twelve different combinations within four simulated scenarios as a combination of decrement values have been implemented and accuracy analysis was performed. Here, a vertical shift procedure on reflectors was applied. Meanwhile, the vertical shift amount was tracked in each computation to determine which reflected signal could be able to use for assigning reflector height as effective. Comparisons of the estimated heights and in-situ measurements show congruency with ±1.2 cm to ±8 cm accuracy. The best overall accuracy of the model among the four scenarios is computed as ±2.2 cm. When the vertical shift decrements are considered, the RMSE values are estimated within ±2.92 cm to ±3.96 cm. Although the RMSEs of the differences show a good agreement with estimated reflector heights, it is found that some reflector height estimations are statistically insignificant.
{"title":"An experimental test for detecting effective reflector height with GPS SNR data","authors":"N. Tunalioglu, Cem Altuntas","doi":"10.15446/esrj.v26n1.87003","DOIUrl":"https://doi.org/10.15446/esrj.v26n1.87003","url":null,"abstract":"This study aims to estimate effective reflector heights and height differences using the basic geometrical principle of multipath theory by controlling the signal quality for estimations. The geometry of the reflecting signal allows computing the effective reflector height, which is extracted from where the signal reflects on the ground and arrives at the GPS antenna phase center. To achieve that, an experimental case with two stations was conducted in the snow-free environment and GPS receivers were mounted on reflectors, which allowed to measure daily in-situ reflector heights and artificial decrement variations. The reflections from the roof surface were tracked with the first-Fresnel zones. To validate the estimated reflector heights in a controlled test environment, twelve different combinations within four simulated scenarios as a combination of decrement values have been implemented and accuracy analysis was performed. Here, a vertical shift procedure on reflectors was applied. Meanwhile, the vertical shift amount was tracked in each computation to determine which reflected signal could be able to use for assigning reflector height as effective. Comparisons of the estimated heights and in-situ measurements show congruency with ±1.2 cm to ±8 cm accuracy. The best overall accuracy of the model among the four scenarios is computed as ±2.2 cm. When the vertical shift decrements are considered, the RMSE values are estimated within ±2.92 cm to ±3.96 cm. Although the RMSEs of the differences show a good agreement with estimated reflector heights, it is found that some reflector height estimations are statistically insignificant.","PeriodicalId":11456,"journal":{"name":"Earth Sciences Research Journal","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48804469","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 : 2022-05-11DOI: 10.15446/esrj.v26n1.95405
Johnny Alexander Vega Gutiérrez, S. Palomino-Ángel, J. Anaya
Structural attributes are fundamental biophysical parameters of forest, useful for ecological and environmental monitoring and planning. Canopy height is an important input for the estimation of several biophysical parameters as aboveground biomass and carbon stock, and can be related with forest degradation, deforestation, and emission reduction. Thus, an accurate canopy height estimation is a crucial issue in climate change studies and REDD+ initiatives. VHR imagery from unmanned aircraft systems has been studied as a low cost mean for canopy height estimation at local scales, but the accuracy in the estimation is a factor that determines its utility. We evaluated the ability of VHR imagery from unmanned aircraft systems to derive structural attributes, specifically tree-crown area and height, in a natural tropical forest fragment located in the foothills of the Andes Mountains, in the humid tropical forests of the region known as Biogeographic Chocó, South America. The region is one of the most biodiverse areas of the world and has a high level of endemism, but it is also at higher risk of natural-resource loss. We used a structure from motion approach to derive canopy height models of the forest fragment, and we applied mean-shift algorithms to identify single tree crowns. The accuracy assessment was performed using reference data derived from field campaigns and visually interpretation of VHR imagery. The estimated root-mean-square error of the population of vertical errors for the canopy height model was 3.6 m. The total accuracy for delineating tree crowns was 73.9%. We found that using VHR imagery, specific trees and canopy gaps can be identified and easily monitored, which is an important step in conservation programs. We also discuss the usefulness of these findings in the context of fragmented forests and the tradeoffs between the price of a LIDAR system and the accuracy of this approach.
{"title":"Structural attributes estimation in a natural tropical forest fragment using very high-resolution imagery from unmanned aircraft systems","authors":"Johnny Alexander Vega Gutiérrez, S. Palomino-Ángel, J. Anaya","doi":"10.15446/esrj.v26n1.95405","DOIUrl":"https://doi.org/10.15446/esrj.v26n1.95405","url":null,"abstract":"Structural attributes are fundamental biophysical parameters of forest, useful for ecological and environmental monitoring and planning. Canopy height is an important input for the estimation of several biophysical parameters as aboveground biomass and carbon stock, and can be related with forest degradation, deforestation, and emission reduction. Thus, an accurate canopy height estimation is a crucial issue in climate change studies and REDD+ initiatives. VHR imagery from unmanned aircraft systems has been studied as a low cost mean for canopy height estimation at local scales, but the accuracy in the estimation is a factor that determines its utility. We evaluated the ability of VHR imagery from unmanned aircraft systems to derive structural attributes, specifically tree-crown area and height, in a natural tropical forest fragment located in the foothills of the Andes Mountains, in the humid tropical forests of the region known as Biogeographic Chocó, South America. The region is one of the most biodiverse areas of the world and has a high level of endemism, but it is also at higher risk of natural-resource loss. We used a structure from motion approach to derive canopy height models of the forest fragment, and we applied mean-shift algorithms to identify single tree crowns. The accuracy assessment was performed using reference data derived from field campaigns and visually interpretation of VHR imagery. The estimated root-mean-square error of the population of vertical errors for the canopy height model was 3.6 m. The total accuracy for delineating tree crowns was 73.9%. We found that using VHR imagery, specific trees and canopy gaps can be identified and easily monitored, which is an important step in conservation programs. We also discuss the usefulness of these findings in the context of fragmented forests and the tradeoffs between the price of a LIDAR system and the accuracy of this approach.","PeriodicalId":11456,"journal":{"name":"Earth Sciences Research Journal","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47730093","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 : 2022-05-11DOI: 10.15446/esrj.v26n1.76468
Reza Khajevand, D. Fereidooni
Fifteen sedimentary rock samples of four rock types including sandstone, limestone, travertine and conglomerate were collected from Damghan area, northern Iran. Mineralogical studies and laboratory experiments were performed to assess physical properties, Schmidt hardness, P-wave velocity, slake-durability index, uniaxial compressive, point load, Brazilian tensile and block punch strengths of the rocks. The studied rock samples are mainly composed of quartz, calcite and dolomite with different textures. The slake-durability test was carried out up to ten cycles in fluids with different pH. The utilized test fluids were natural water with pH of 7 and sulfuric acid solutions with pH of 5.5 and 4. Based on the results, the slake-durability index is affected by pH of the test fluids. Also, the different rock types had distinctive slaking behaviors. Decreasing rate of slake-durability index at initial cycles is higher than the end cycles the same as weight loss rate of the specimens. Regression analyses showed that the evaluated parameters are correlated to the slake-durability index. In other words, the slake-durability index of the studied rock samples is greatly affected by their mineral composition, texture, physical properties such as porosity and closely related to strength parameters of the rocks. This led to extraction of empirical equations for determining essential characteristics of the rocks from the slake-durability index.
{"title":"The effects of water acidity and engineering properties on rock durability","authors":"Reza Khajevand, D. Fereidooni","doi":"10.15446/esrj.v26n1.76468","DOIUrl":"https://doi.org/10.15446/esrj.v26n1.76468","url":null,"abstract":"Fifteen sedimentary rock samples of four rock types including sandstone, limestone, travertine and conglomerate were collected from Damghan area, northern Iran. Mineralogical studies and laboratory experiments were performed to assess physical properties, Schmidt hardness, P-wave velocity, slake-durability index, uniaxial compressive, point load, Brazilian tensile and block punch strengths of the rocks. The studied rock samples are mainly composed of quartz, calcite and dolomite with different textures. The slake-durability test was carried out up to ten cycles in fluids with different pH. The utilized test fluids were natural water with pH of 7 and sulfuric acid solutions with pH of 5.5 and 4. Based on the results, the slake-durability index is affected by pH of the test fluids. Also, the different rock types had distinctive slaking behaviors. Decreasing rate of slake-durability index at initial cycles is higher than the end cycles the same as weight loss rate of the specimens. Regression analyses showed that the evaluated parameters are correlated to the slake-durability index. In other words, the slake-durability index of the studied rock samples is greatly affected by their mineral composition, texture, physical properties such as porosity and closely related to strength parameters of the rocks. This led to extraction of empirical equations for determining essential characteristics of the rocks from the slake-durability index.","PeriodicalId":11456,"journal":{"name":"Earth Sciences Research Journal","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43072819","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}
In the face of endless idle and even abandoned farmland, it is trying to protect farmland resources and ensure food supply by determining the bottom line (red line) of arable land that cannot be changed in use. The red line has landscape characteristics and functions, but there remain limited understandings of how to judge the dominant landscape characteristics of cultivated land. Therefore, this study divides landscape characteristics into aesthetic value and stability according to landscape pattern. A comprehensive evaluation system was developed to explore the dominant landscape features of the cultivated resources based on a multi-factor comprehensive evaluation. On this basis, this study conducts an empirical study in Donggang, a coastal city in China. The results show that cultivated land resources with high aesthetic value are distributed near cities, major roads, and important natural resources. The cultivated land resources with greater continuity and compatibility with adjacent plots are relatively stable, mainly paddy fields. The red line of cultivated land should focus on the characteristics of cultivated land stability. At the same time, the aesthetic value of cultivated land resources is also an important factor (related degree is 0.852). According to this evaluation system, the dominant area of arable land protection in Donggang City is 88,027.21hm2, which is the preferred area for the red line of arable land.
{"title":"Dominant landscape characteristics of the arable land red line in Donggang, China","authors":"Fengkui Qian, Weiwen Wang, Xuefeng Zhang, Jingye Zhang, Zhenxing Bian","doi":"10.15446/esrj.v26n1.62063","DOIUrl":"https://doi.org/10.15446/esrj.v26n1.62063","url":null,"abstract":"In the face of endless idle and even abandoned farmland, it is trying to protect farmland resources and ensure food supply by determining the bottom line (red line) of arable land that cannot be changed in use. The red line has landscape characteristics and functions, but there remain limited understandings of how to judge the dominant landscape characteristics of cultivated land. Therefore, this study divides landscape characteristics into aesthetic value and stability according to landscape pattern. A comprehensive evaluation system was developed to explore the dominant landscape features of the cultivated resources based on a multi-factor comprehensive evaluation. On this basis, this study conducts an empirical study in Donggang, a coastal city in China. The results show that cultivated land resources with high aesthetic value are distributed near cities, major roads, and important natural resources. The cultivated land resources with greater continuity and compatibility with adjacent plots are relatively stable, mainly paddy fields. The red line of cultivated land should focus on the characteristics of cultivated land stability. At the same time, the aesthetic value of cultivated land resources is also an important factor (related degree is 0.852). According to this evaluation system, the dominant area of arable land protection in Donggang City is 88,027.21hm2, which is the preferred area for the red line of arable land.","PeriodicalId":11456,"journal":{"name":"Earth Sciences Research Journal","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48754992","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 : 2022-05-11DOI: 10.15446/esrj.v26n1.92419
Edwin Naranjo Sierra
Shear zone hosted lode gold type deposits at the El Bagre in the northeastern zone of Antioquia department of Colombia, are the only evidence of Permian gold mineralization to date in Colombia Andes. Orebodies at the El Bagre are structurally controlled and are considered as the product of ore-forming fluids derived from at least two episodes of fluid flow between the shear zones, thus different fluid flow could lead to orebodies and ore shoots plunge in different directions. The La Ye orebodies tend to strike to the NNW-NS and plunge to the SW, Mangos orebodies tend to strike (as a whole) to the NS-NNE and plunge to the NE and Cordero orebodies tend to strike (as a whole) to the NNW-NS and plunge to the NE. The ellipses determined by variogram modelling for these orebodies, reveal the anisotropy of gold mineralization and therefore the orientation of ore-shoots. The long axes of the anisotropy ellipses trend SSE. These high grades distributions are related to sinistral shearing and NNW-SSE faulting during D3 deformation event. This study exemplifies a simple and effective tool for exploration strategies regarding of orebodies, ore-shoots and ore-controlling structures relationships
{"title":"Ore-controlling structures and geostatistical determination of ore-shoots in shear zone hosted lode gold type deposits, El Bagre-Antioquia, Colombia","authors":"Edwin Naranjo Sierra","doi":"10.15446/esrj.v26n1.92419","DOIUrl":"https://doi.org/10.15446/esrj.v26n1.92419","url":null,"abstract":"Shear zone hosted lode gold type deposits at the El Bagre in the northeastern zone of Antioquia department of Colombia, are the only evidence of Permian gold mineralization to date in Colombia Andes. Orebodies at the El Bagre are structurally controlled and are considered as the product of ore-forming fluids derived from at least two episodes of fluid flow between the shear zones, thus different fluid flow could lead to orebodies and ore shoots plunge in different directions. The La Ye orebodies tend to strike to the NNW-NS and plunge to the SW, Mangos orebodies tend to strike (as a whole) to the NS-NNE and plunge to the NE and Cordero orebodies tend to strike (as a whole) to the NNW-NS and plunge to the NE. The ellipses determined by variogram modelling for these orebodies, reveal the anisotropy of gold mineralization and therefore the orientation of ore-shoots. The long axes of the anisotropy ellipses trend SSE. These high grades distributions are related to sinistral shearing and NNW-SSE faulting during D3 deformation event. This study exemplifies a simple and effective tool for exploration strategies regarding of orebodies, ore-shoots and ore-controlling structures relationships","PeriodicalId":11456,"journal":{"name":"Earth Sciences Research Journal","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43882832","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 : 2022-05-11DOI: 10.15446/esrj.v26n1.81087
Sara Alcalde-Aparicio, M. Vidal-Bardán, E. Alonso-Herrero
This paper presents detailed mineralogical results together with a geochemical characterization for a sequence of six natural soil profiles. Bedrock samples (R series) and overlying soil samples (S series) were characterized. The soil profiles are distributed in a series of Paleozoic lithological units from lower Ordovician to upper Carboniferous in age (Iberian Massif, NW Iberia). The lithological influence on mineral properties and geochemical composition and, how different weathering may be occurring under very similar temperate and acidic conditions, have been studied. Field observations together with laboratory analyses were indicative of differential weathering. So, a series of selected chemical indices and relations were applied to clarify this assumption. The mineralogy was analysed by Scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD) of rock powder and soil oriented aggregates. X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectroscopy (ICP-MS) were applied to analyse chemical composition. The first results showed how major elements, SiO2, Al2O3 and Fe2O3, slightly enriched in the soil profiles, are consistent with the dominant mineralogy: quartz, chlorite, muscovite and/or illite, together with kaolinite and albite. The bases K2O, Na2O, CaO and MgO are also coherent with mineral composition and experience little variation, but are gradually removed in the profiles. The mobility of major elements leads to a general loss of bases and, in general, a slight enrichment in silica and sesquioxides. SiO2 is enriched, firstly accumulated in soils and partially depleted by dissolution as colloidal form. Al2O3 in some soils is slightly less than in former rocks, so other physical processes are expected to take place, involving clay removal with consequent aluminium depletion too. A special emphasis has been given to albite coexisting with kaolinite, firstly supposed to be directly inherited from parent substrates when present, but finally the chemical index PIA shows it was mainly due to mineral alteration of plagioclases. The best correlations to explain the albite alteration and kaolinitization progress were obtained with chemical indices PIA, CIW, CIA and Al2O3/Na2O ratio. This together with mineralogical signatures, suggest that kaolinite is the result of gradual dissolution due to the acid hydrolysis of albite in such acidic environments, which may also be attributed to the organic matter influence.
{"title":"Mineralogy and geochemical signatures as indicators of differential weathering in natural soil profiles from the West Asturian-Leonese Zone (NW Iberia)","authors":"Sara Alcalde-Aparicio, M. Vidal-Bardán, E. Alonso-Herrero","doi":"10.15446/esrj.v26n1.81087","DOIUrl":"https://doi.org/10.15446/esrj.v26n1.81087","url":null,"abstract":"This paper presents detailed mineralogical results together with a geochemical characterization for a sequence of six natural soil profiles. Bedrock samples (R series) and overlying soil samples (S series) were characterized. The soil profiles are distributed in a series of Paleozoic lithological units from lower Ordovician to upper Carboniferous in age (Iberian Massif, NW Iberia). The lithological influence on mineral properties and geochemical composition and, how different weathering may be occurring under very similar temperate and acidic conditions, have been studied. Field observations together with laboratory analyses were indicative of differential weathering. So, a series of selected chemical indices and relations were applied to clarify this assumption. The mineralogy was analysed by Scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD) of rock powder and soil oriented aggregates. X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectroscopy (ICP-MS) were applied to analyse chemical composition. The first results showed how major elements, SiO2, Al2O3 and Fe2O3, slightly enriched in the soil profiles, are consistent with the dominant mineralogy: quartz, chlorite, muscovite and/or illite, together with kaolinite and albite. The bases K2O, Na2O, CaO and MgO are also coherent with mineral composition and experience little variation, but are gradually removed in the profiles. The mobility of major elements leads to a general loss of bases and, in general, a slight enrichment in silica and sesquioxides. SiO2 is enriched, firstly accumulated in soils and partially depleted by dissolution as colloidal form. Al2O3 in some soils is slightly less than in former rocks, so other physical processes are expected to take place, involving clay removal with consequent aluminium depletion too. A special emphasis has been given to albite coexisting with kaolinite, firstly supposed to be directly inherited from parent substrates when present, but finally the chemical index PIA shows it was mainly due to mineral alteration of plagioclases. The best correlations to explain the albite alteration and kaolinitization progress were obtained with chemical indices PIA, CIW, CIA and Al2O3/Na2O ratio. This together with mineralogical signatures, suggest that kaolinite is the result of gradual dissolution due to the acid hydrolysis of albite in such acidic environments, which may also be attributed to the organic matter influence.","PeriodicalId":11456,"journal":{"name":"Earth Sciences Research Journal","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46253450","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 : 2022-05-11DOI: 10.15446/esrj.v26n1.83186
Shahrzad Ameri, A. Solgi, A. Sorbi, Alireza Farrokhnia
The morphotectonic analysis is a useful time-saving and cost-effective method to assess tectonic activity, especially in large regions. In this paper, the morphotectonic study was carried out in Kerman city which is in the southeast of Iran and is a part of the Central Iran structural zone. Despite the occurrence of numerous historical and instrumental earthquakes around Kerman city, there is a gap in earthquake records of this city that has obscured its seismicity status. The aim of this study is to identify active faults and the associated seismic hazard to Kerman city. For this purpose, seven geomorphic indices namely stream length-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), index of drainage basin shape (Bs), index of mountain front sinuosity (Smf) and Transverse Topographic Symmetry Factor (T) were examined for 51 basins of the study area, using digital elevation model (DEM) and geological maps in a GIS environment. Then, two kinds of relative tectonic activity index were calculated for each basin, i.e., Iat and Iat_T, from the combination of these indices. The Iat_T was chosen because its results show better agreement with the structural geology and seismic records of this region. Finally, the study area was divided into three regions according to the Iat_T values. The morphotectonic analyses indicate that the Kuhbanan fault system, especially its southern splays, has the potential to produce serious seismic hazards to Kerman city in the future; the Mahan-Jupar fault-related folds, the southern tip of the Jorjafk fault, the probable fault of Zangi-Abad, the Rafsanjan-Zarand fault system, and Gowk fault are considered as other threats to Kerman city. Furthermore, this study reveals that morphotectonic analysis is a reliable tool to evaluate fault capability and to determine the fault types, and therefore to estimate seismotectonic hazard.
{"title":"Identification of faults with seismic hazard potential based on morphotectonic analysis, Kerman city (Southeastern Iran)","authors":"Shahrzad Ameri, A. Solgi, A. Sorbi, Alireza Farrokhnia","doi":"10.15446/esrj.v26n1.83186","DOIUrl":"https://doi.org/10.15446/esrj.v26n1.83186","url":null,"abstract":"The morphotectonic analysis is a useful time-saving and cost-effective method to assess tectonic activity, especially in large regions. In this paper, the morphotectonic study was carried out in Kerman city which is in the southeast of Iran and is a part of the Central Iran structural zone. Despite the occurrence of numerous historical and instrumental earthquakes around Kerman city, there is a gap in earthquake records of this city that has obscured its seismicity status. The aim of this study is to identify active faults and the associated seismic hazard to Kerman city. For this purpose, seven geomorphic indices namely stream length-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), index of drainage basin shape (Bs), index of mountain front sinuosity (Smf) and Transverse Topographic Symmetry Factor (T) were examined for 51 basins of the study area, using digital elevation model (DEM) and geological maps in a GIS environment. Then, two kinds of relative tectonic activity index were calculated for each basin, i.e., Iat and Iat_T, from the combination of these indices. The Iat_T was chosen because its results show better agreement with the structural geology and seismic records of this region. Finally, the study area was divided into three regions according to the Iat_T values. The morphotectonic analyses indicate that the Kuhbanan fault system, especially its southern splays, has the potential to produce serious seismic hazards to Kerman city in the future; the Mahan-Jupar fault-related folds, the southern tip of the Jorjafk fault, the probable fault of Zangi-Abad, the Rafsanjan-Zarand fault system, and Gowk fault are considered as other threats to Kerman city. Furthermore, this study reveals that morphotectonic analysis is a reliable tool to evaluate fault capability and to determine the fault types, and therefore to estimate seismotectonic hazard.","PeriodicalId":11456,"journal":{"name":"Earth Sciences Research Journal","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41892753","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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