Dikes are widely distributed in volcanic outcrops and volcanic basins around the world.The pores and fractures in these dikes control the fluid-rock interactions and fluid flow.The quantitative reservoir characteristi...Dikes are widely distributed in volcanic outcrops and volcanic basins around the world.The pores and fractures in these dikes control the fluid-rock interactions and fluid flow.The quantitative reservoir characteristics of dikes with primary vesicles remain unclear.In this manuscript,the Miocene hypabyssal dikes in Lyttelton Volcano,Christchurch,New Zealand,are taken as an example.The porosity content,porosity,permeability,and reservoir controlling factors are analyzed through field outcrop surveys,porosity-permeability testing,nuclear magnetic resonance(NMR)testing,X-ray-computed tomography(X-CT)scanning,and permeability calculations.The results show that the types of reservoir spaces in the hypabyssal dikes in Lyttelton Volcano are mainly vesicles,followed by cooling and shrinkage fractures(especially columnar joints).They are a pore-fracture type reservoir.There were two types of vesicles,namely,pipe-like-elliptical directionally oriented vesicles with large diameters and discrete circular vesicles with small diameters.The surface porosity of the former was 58.4%–96.0%,with a geometric mean of 78.9%.The columnar joints can be classified into regular and irregular joints.The irregular joints have a higher fracture intensity.The geometric means of the porosity and permeability of the joints are 22.34%and 0.09×10^(-15)m^(2),respectively.The shapes of the NMR T_(2)spectra are bimodal,trimodal,and unimodal in descending order of abundance.This means that the pore diameter is large.The X-CT results indicate that there are four types of pore-throat connectivity modes:macro-pores and macro-throats,macro-pores and micro-throats,micro-pores and micro-throats,and micro-pores and macrothroats.The columnar joints are the main cause of the high permeability of the dikes,and the side amount and side length of the columnar joints control the dikes'permeability.The pores can be connected by the columnar joints,and their connectivity is controlled by the side amount,side length,and side azimuth of the columnar joint.The initial connectivity ratio of the vesicles in the dikes in Lyttelton Volcano was up to 47.6%based on the surface porosity.In conclusion,the shallow dikes with primary pores and fractures have a good reservoir quality and fluid migration capacity,and fluid flow studies of volcanic strata should pay attention to the important influence of the primary porosity and permeability of dikes.展开更多
The 7 ka old Qixiangzhan lava flow(QXZ,Tianchi volcano)represents the last eruptive event before the 946 CE,caldera-forming‘Millennium’eruption(ME).Petrographic,whole rock,mineral composition,Sr-Nd isotopic data on ...The 7 ka old Qixiangzhan lava flow(QXZ,Tianchi volcano)represents the last eruptive event before the 946 CE,caldera-forming‘Millennium’eruption(ME).Petrographic,whole rock,mineral composition,Sr-Nd isotopic data on QXZ show that:(a)the lava consists of two components,constituted by comenditic obsidian fragments immersed in a continuous,aphanitic component;(b)both components have the same geochemical and isotopic variations of the ME magma.The QXZ and ME comendites result from fractional crystallization and crustal assimilation processes.The temperature of the QXZ magma was about 790℃ and the depth of the magma reservoir around 7 km,the same values as estimated for ME.QXZ had a viscosity of 10^(5.5)-10^(9) Pa s and a velocity of 3-10 km/yr.The emplacement time was 0.5-1.6yr and the flow rate 0.48-1.50 m^(3)/s.These values lie within the range estimated for other rhyolitic flows worldwide.The QXZ lava originated through a mixed explosive-effusive activity with the obsidian resulting from the ascent of undercooling,degassing and the fragmentation of magma along the conduit walls,whereas the aphanitic component testifies to the less undercooled and segregated flow at the center of the conduit.The QXZ lava demonstrates the extensive history of the ME magma chamber.展开更多
The phenomenon of mud volcanism has a connection with the processes of hydrocarbon generation.However,the genesis of sediments is not often taken into consideration.The study of mud volcanoes in the West Kuban margina...The phenomenon of mud volcanism has a connection with the processes of hydrocarbon generation.However,the genesis of sediments is not often taken into consideration.The study of mud volcanoes in the West Kuban marginal marine basin and the Junggar freshwater basin revealed significant isotope-geochemical differences due to various types of sedimentation.The waters from both basins exhibit three principal geochemical facies:Na-HCO_(3),Na-Cl-HCO_(3),and Na-Cl,of which the latter type of water is the dominant.The analysis of genetic coefficients(Cl/Br,Na/Br,and B/Cl)allowed us to distinguish different pathways of mud volcanic water evolution:evaporite dissolution,formation(sedimentation)waters,and waters formed by active water-rock interaction.Through statistical research,we were able to determine that noticeable variations in the behavior of chemical elements in waters from different areas can reflect discrepancies in the geological environment and the evolutionary stage of the diagenetic water transformation.Using thermodynamic modeling,the main directions of mass transfer were shown.It was established that the waters of the Junggar Basin were at a relatively early stage of evolution and had reached equilibrium only with carbonates,while in the formation waters of the West Kuban Basin,element concentrations were also controlled by silicate minerals.The correlations betweenδ^(18)O andδ~2H values and saturation indices of halides,aluminosilicates,sulfates,and borates confirm the enrichment of water with heavy isotopes during interactions with rocks without evaporation or thermal water partition.These reactions are characterized by clay dehydration and water enrichment with^(18)O and B.The data obtained made it possible to clarify the depths of formation of mud-volcanic fluids and their possible stratigraphic sources.展开更多
The thought of living near an active volcano probably sounds like an unimaginable experience-and rightly so.An active volcano can turn a forested hillside into a lifeless wasteland in seconds.From molten avalanches of...The thought of living near an active volcano probably sounds like an unimaginable experience-and rightly so.An active volcano can turn a forested hillside into a lifeless wasteland in seconds.From molten avalanches of rock to razor-sharp lung-shredding ash,volcanoes threaten people's lives and property.展开更多
The release of accumulated stress through earthquakes is known to devote to the mud volcanism occurrence,which may in turn affect subsequent regional seismicity.Mud volcanoes have been observed on the northeast contin...The release of accumulated stress through earthquakes is known to devote to the mud volcanism occurrence,which may in turn affect subsequent regional seismicity.Mud volcanoes have been observed on the northeast continental margin of the South China Sea as well.Based on the mud volcanoes and earthquakes catalogue,we measured the spatial and temporal distribution of z and b values,to explore the geodynamic process of the repeated eruptions of mud volcanoes influence on the regional seismicity.The results suggest a close correlation between the b-z values and mud volcanism occurrence in the SW Taiwan.Generally,the z-value anomalies in where the mud volcanoes eruptions show unchanged negative values and indicate seismic quiescence before a big earthquake,whereas the b-values often show periodicity fluctuations around the value of 0.5.This may indicate a mutual triggering relationship between the mud volcanoes and earthquakes.We infer that mud volcano eruptions help to partition and release part of the regional stress accumulation from the seismogenic structures,thus balancing the local stress and mitigating large-magnitude seismicity occurring probability.展开更多
Multifarious regions around the world are exposed to natural hazards and disasters,each with unique characteristics.A higher frequency of extreme hydro-meteorological events,most probably related to climate change,and...Multifarious regions around the world are exposed to natural hazards and disasters,each with unique characteristics.A higher frequency of extreme hydro-meteorological events,most probably related to climate change,and an increase in vulnerable population have been addressed as potential causes of such disasters.To mitigate the consequences of these disasters,Disaster Risk Management,including hazard assessment,elements-at-risk mapping,vulnerability and risk assessment of spatial components as well as Earth Observation(EO)products and Geographic Information Systems(GIS),should be considered.Multihazard assessment entails the evaluation of relationships between various hazards,including interconnected or cascading events,as well as focusing on various levels from global to local community levels,as each level manifests particular objectives and spatial data.This paper presents an overview of the diverse types of spatial data and explores the methods applied in hazard and risk assessments,with volcanic eruptions serving as a specific example.The rapid development of scientific research and the advancement of Earth Observation satellites in recent years have revolutionized the concepts of geologists and researchers.These satellites now play an indispensable role in supporting first responders during major disasters.The coordination of satellite deployment ensures a swift response along with allowing for the timely delivery of critical images.In tandem,remote sensing technologies and geographic information systems(GIS)have emerged as essential tools for geospatial analysis.The application of remote sensing and GIS for the detection of natural disasters was examined through a review of academic papers,offering an analysis of how remote sensing is utilized to assess natural hazards and their link to climate change.展开更多
Cenozoic trachytes are characteristic of some active volcanic fields in China.In particular,the origin and mechanisms of the evolution of trachytes from the Tianchi(Changbaishan)volcano(TV,China/North Korea)are poorly...Cenozoic trachytes are characteristic of some active volcanic fields in China.In particular,the origin and mechanisms of the evolution of trachytes from the Tianchi(Changbaishan)volcano(TV,China/North Korea)are poorly known.Here,we present new geochronological,geochemical and isotopic data on two trachytic suites outcropping on the northern and southern upper slopes of TV.Detailed zircon laser ablation-multicollector-inductively coupled plasma-mass spectrometry(LA-MC-ICP-MS)U-Pb dating,Rb-Sr isochron dating of plagioclase and hornblende,^(40)Ar/^(39)Ar chronology with mineral chemistry,whole-rock element and Sr-Nd-Pb isotope data are used to explore their origins and evolutionary mechanisms during the late Middle Pleistocene.Our data indicate that the trachytes mainly consist of sanidine,orthoclase and plagioclase,with minor albite,quartz and hornblende.They formed at 0.353-0.346 Ma(lava flow from the northern slope)and 0.383-0.311 Ma(lava flow from the southern slope),respectively.The TV trachytes are characterized by high K_(2)O/Na_(2)O and AR values,with low A/CNK and Mg~#values.They are enriched in rare earth elements(REEs;except Eu),depleted in Sr and Ba,crystallizing at 742-858℃.The TV trachytes have high(^(87)Sr/^(86)Sr)_i values(0.70776-0.71195),positiveε_(Nd)(t)values(0.61-2.93)and radiogenic^(206)Pb/^(204)Pb values(17.515-17.806).These values are similar to those of the Pleistocene and Holocene TV trachytes.Geochemical data indicate that they were formed by fractional crystallization from a basaltic melt and assimilated upper crust material.The trace element pattern of the studied trachytes is consistent with an evolution from basaltic melts representative of an enriched mantle source.The vent from which the trachytic magma was erupted probably collapsed inside the caldera during the TV'Millennium'eruption(ME)in 946 AD.The contemporaneous emission of basaltic and trachytic magma during the Middle-Late Pleistocene suggests the coexistence of fissural basaltic volcanism and central-type trachytic volcanism,the latter of which was associated with a magma chamber in the upper crust during the TV cone-construction stage.展开更多
[Objective]To seek one effective extraction method of metagenomic DNA from mud volcano.[Method]The metagenomic DNA from mud volcano was extracted by CTAB extraction method,SDS-enzyme method,improved method,reagent kit...[Objective]To seek one effective extraction method of metagenomic DNA from mud volcano.[Method]The metagenomic DNA from mud volcano was extracted by CTAB extraction method,SDS-enzyme method,improved method,reagent kit method.The extraction of four kinds of methods were compared.[Result]The extracted rate in reagent sets method was the highest,next was improved method,the extracted quantity in SDS-enzyme method was maximum.DNA extracted by the improved method was diluted ten times for PCR.[Conclusion]Considering economy and purity,the improved method can be used as one effective extraction method of metagenomic DNA from mud volcano.展开更多
基金supported by the National Key R&D Program of China(No.2019YFC0605402)the National Natural Science Foundation of China(No.41790453)。
文摘Dikes are widely distributed in volcanic outcrops and volcanic basins around the world.The pores and fractures in these dikes control the fluid-rock interactions and fluid flow.The quantitative reservoir characteristics of dikes with primary vesicles remain unclear.In this manuscript,the Miocene hypabyssal dikes in Lyttelton Volcano,Christchurch,New Zealand,are taken as an example.The porosity content,porosity,permeability,and reservoir controlling factors are analyzed through field outcrop surveys,porosity-permeability testing,nuclear magnetic resonance(NMR)testing,X-ray-computed tomography(X-CT)scanning,and permeability calculations.The results show that the types of reservoir spaces in the hypabyssal dikes in Lyttelton Volcano are mainly vesicles,followed by cooling and shrinkage fractures(especially columnar joints).They are a pore-fracture type reservoir.There were two types of vesicles,namely,pipe-like-elliptical directionally oriented vesicles with large diameters and discrete circular vesicles with small diameters.The surface porosity of the former was 58.4%–96.0%,with a geometric mean of 78.9%.The columnar joints can be classified into regular and irregular joints.The irregular joints have a higher fracture intensity.The geometric means of the porosity and permeability of the joints are 22.34%and 0.09×10^(-15)m^(2),respectively.The shapes of the NMR T_(2)spectra are bimodal,trimodal,and unimodal in descending order of abundance.This means that the pore diameter is large.The X-CT results indicate that there are four types of pore-throat connectivity modes:macro-pores and macro-throats,macro-pores and micro-throats,micro-pores and micro-throats,and micro-pores and macrothroats.The columnar joints are the main cause of the high permeability of the dikes,and the side amount and side length of the columnar joints control the dikes'permeability.The pores can be connected by the columnar joints,and their connectivity is controlled by the side amount,side length,and side azimuth of the columnar joint.The initial connectivity ratio of the vesicles in the dikes in Lyttelton Volcano was up to 47.6%based on the surface porosity.In conclusion,the shallow dikes with primary pores and fractures have a good reservoir quality and fluid migration capacity,and fluid flow studies of volcanic strata should pay attention to the important influence of the primary porosity and permeability of dikes.
基金funded by the National Natural Science Foundation of China(Grant Nos.41972313 and 41790453)the Engineering Research Center of Geothermal Resources Development Technology and Equipment,Ministry of Education,Jilin University。
文摘The 7 ka old Qixiangzhan lava flow(QXZ,Tianchi volcano)represents the last eruptive event before the 946 CE,caldera-forming‘Millennium’eruption(ME).Petrographic,whole rock,mineral composition,Sr-Nd isotopic data on QXZ show that:(a)the lava consists of two components,constituted by comenditic obsidian fragments immersed in a continuous,aphanitic component;(b)both components have the same geochemical and isotopic variations of the ME magma.The QXZ and ME comendites result from fractional crystallization and crustal assimilation processes.The temperature of the QXZ magma was about 790℃ and the depth of the magma reservoir around 7 km,the same values as estimated for ME.QXZ had a viscosity of 10^(5.5)-10^(9) Pa s and a velocity of 3-10 km/yr.The emplacement time was 0.5-1.6yr and the flow rate 0.48-1.50 m^(3)/s.These values lie within the range estimated for other rhyolitic flows worldwide.The QXZ lava originated through a mixed explosive-effusive activity with the obsidian resulting from the ascent of undercooling,degassing and the fragmentation of magma along the conduit walls,whereas the aphanitic component testifies to the less undercooled and segregated flow at the center of the conduit.The QXZ lava demonstrates the extensive history of the ME magma chamber.
基金partly supported by the NSFC-RSF Joint Research project(Nos.42261134534,23-47-00035)funded by the Chinese Academy of Sciences President’s International Fellowship Initiative(Nos.2024VCA0006,2024VCB0013)the National Natural Science Foundation of China(No.42442006)。
文摘The phenomenon of mud volcanism has a connection with the processes of hydrocarbon generation.However,the genesis of sediments is not often taken into consideration.The study of mud volcanoes in the West Kuban marginal marine basin and the Junggar freshwater basin revealed significant isotope-geochemical differences due to various types of sedimentation.The waters from both basins exhibit three principal geochemical facies:Na-HCO_(3),Na-Cl-HCO_(3),and Na-Cl,of which the latter type of water is the dominant.The analysis of genetic coefficients(Cl/Br,Na/Br,and B/Cl)allowed us to distinguish different pathways of mud volcanic water evolution:evaporite dissolution,formation(sedimentation)waters,and waters formed by active water-rock interaction.Through statistical research,we were able to determine that noticeable variations in the behavior of chemical elements in waters from different areas can reflect discrepancies in the geological environment and the evolutionary stage of the diagenetic water transformation.Using thermodynamic modeling,the main directions of mass transfer were shown.It was established that the waters of the Junggar Basin were at a relatively early stage of evolution and had reached equilibrium only with carbonates,while in the formation waters of the West Kuban Basin,element concentrations were also controlled by silicate minerals.The correlations betweenδ^(18)O andδ~2H values and saturation indices of halides,aluminosilicates,sulfates,and borates confirm the enrichment of water with heavy isotopes during interactions with rocks without evaporation or thermal water partition.These reactions are characterized by clay dehydration and water enrichment with^(18)O and B.The data obtained made it possible to clarify the depths of formation of mud-volcanic fluids and their possible stratigraphic sources.
文摘The thought of living near an active volcano probably sounds like an unimaginable experience-and rightly so.An active volcano can turn a forested hillside into a lifeless wasteland in seconds.From molten avalanches of rock to razor-sharp lung-shredding ash,volcanoes threaten people's lives and property.
基金supported by the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.SML2021SP318)the National Postdoctoral Program for Innovative Talents(No.BX20190391)+1 种基金the Guangdong Province Introduced Innovative R&D Team of Geological Processes and Natural Disasters around the South China Sea founded by the Science and Technology Department of Guangdong Province(No.2016ZT06N331)the Guangdong Basic and Applied Basic Research Foundation(Nos.2019A1515110305,2021A1515011130,2021A1515110288)。
文摘The release of accumulated stress through earthquakes is known to devote to the mud volcanism occurrence,which may in turn affect subsequent regional seismicity.Mud volcanoes have been observed on the northeast continental margin of the South China Sea as well.Based on the mud volcanoes and earthquakes catalogue,we measured the spatial and temporal distribution of z and b values,to explore the geodynamic process of the repeated eruptions of mud volcanoes influence on the regional seismicity.The results suggest a close correlation between the b-z values and mud volcanism occurrence in the SW Taiwan.Generally,the z-value anomalies in where the mud volcanoes eruptions show unchanged negative values and indicate seismic quiescence before a big earthquake,whereas the b-values often show periodicity fluctuations around the value of 0.5.This may indicate a mutual triggering relationship between the mud volcanoes and earthquakes.We infer that mud volcano eruptions help to partition and release part of the regional stress accumulation from the seismogenic structures,thus balancing the local stress and mitigating large-magnitude seismicity occurring probability.
文摘Multifarious regions around the world are exposed to natural hazards and disasters,each with unique characteristics.A higher frequency of extreme hydro-meteorological events,most probably related to climate change,and an increase in vulnerable population have been addressed as potential causes of such disasters.To mitigate the consequences of these disasters,Disaster Risk Management,including hazard assessment,elements-at-risk mapping,vulnerability and risk assessment of spatial components as well as Earth Observation(EO)products and Geographic Information Systems(GIS),should be considered.Multihazard assessment entails the evaluation of relationships between various hazards,including interconnected or cascading events,as well as focusing on various levels from global to local community levels,as each level manifests particular objectives and spatial data.This paper presents an overview of the diverse types of spatial data and explores the methods applied in hazard and risk assessments,with volcanic eruptions serving as a specific example.The rapid development of scientific research and the advancement of Earth Observation satellites in recent years have revolutionized the concepts of geologists and researchers.These satellites now play an indispensable role in supporting first responders during major disasters.The coordination of satellite deployment ensures a swift response along with allowing for the timely delivery of critical images.In tandem,remote sensing technologies and geographic information systems(GIS)have emerged as essential tools for geospatial analysis.The application of remote sensing and GIS for the detection of natural disasters was examined through a review of academic papers,offering an analysis of how remote sensing is utilized to assess natural hazards and their link to climate change.
基金financially supported by the project of the National Observation and Research Station of the Institute of Geology,China Earthquake Administration(Grant No.NORSCBS22-06)the Youth Science and Technology Development Project of the Jilin Earthquake Agency(Grant No.JZQ-202402)+1 种基金the Earthquake Science and Technology Spark Project(Grant No.XH23013B)the China Scholarship Council(Grant No.202104190014)。
文摘Cenozoic trachytes are characteristic of some active volcanic fields in China.In particular,the origin and mechanisms of the evolution of trachytes from the Tianchi(Changbaishan)volcano(TV,China/North Korea)are poorly known.Here,we present new geochronological,geochemical and isotopic data on two trachytic suites outcropping on the northern and southern upper slopes of TV.Detailed zircon laser ablation-multicollector-inductively coupled plasma-mass spectrometry(LA-MC-ICP-MS)U-Pb dating,Rb-Sr isochron dating of plagioclase and hornblende,^(40)Ar/^(39)Ar chronology with mineral chemistry,whole-rock element and Sr-Nd-Pb isotope data are used to explore their origins and evolutionary mechanisms during the late Middle Pleistocene.Our data indicate that the trachytes mainly consist of sanidine,orthoclase and plagioclase,with minor albite,quartz and hornblende.They formed at 0.353-0.346 Ma(lava flow from the northern slope)and 0.383-0.311 Ma(lava flow from the southern slope),respectively.The TV trachytes are characterized by high K_(2)O/Na_(2)O and AR values,with low A/CNK and Mg~#values.They are enriched in rare earth elements(REEs;except Eu),depleted in Sr and Ba,crystallizing at 742-858℃.The TV trachytes have high(^(87)Sr/^(86)Sr)_i values(0.70776-0.71195),positiveε_(Nd)(t)values(0.61-2.93)and radiogenic^(206)Pb/^(204)Pb values(17.515-17.806).These values are similar to those of the Pleistocene and Holocene TV trachytes.Geochemical data indicate that they were formed by fractional crystallization from a basaltic melt and assimilated upper crust material.The trace element pattern of the studied trachytes is consistent with an evolution from basaltic melts representative of an enriched mantle source.The vent from which the trachytic magma was erupted probably collapsed inside the caldera during the TV'Millennium'eruption(ME)in 946 AD.The contemporaneous emission of basaltic and trachytic magma during the Middle-Late Pleistocene suggests the coexistence of fissural basaltic volcanism and central-type trachytic volcanism,the latter of which was associated with a magma chamber in the upper crust during the TV cone-construction stage.
基金Supported by National Natural Science Foundation of China~~
文摘[Objective]To seek one effective extraction method of metagenomic DNA from mud volcano.[Method]The metagenomic DNA from mud volcano was extracted by CTAB extraction method,SDS-enzyme method,improved method,reagent kit method.The extraction of four kinds of methods were compared.[Result]The extracted rate in reagent sets method was the highest,next was improved method,the extracted quantity in SDS-enzyme method was maximum.DNA extracted by the improved method was diluted ten times for PCR.[Conclusion]Considering economy and purity,the improved method can be used as one effective extraction method of metagenomic DNA from mud volcano.
