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
We synthesize significant recent results on the deep structure and origin of the active volcanoes in China's Mainland. Magmatism in the western Pacific arc and back-arc areas is caused by dehydration of the subduc...We synthesize significant recent results on the deep structure and origin of the active volcanoes in China's Mainland. Magmatism in the western Pacific arc and back-arc areas is caused by dehydration of the subducting slab and by corner flow in the mantle wedge, whereas the intraplate magmatism in China has different origins. The active volcanoes in Northeast China （such as the Changbai and Wudalianchi） are caused by hot upwelling in the big mantle wedge （BMW） above the stagnant slab in the mantle transition zone and deep slab dehydration as well. The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate （or Indian plate）. The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs＇ deep subduction in the east and the Indian slab＇s deep subduction in the west down to the lower mantle. The stagnant slab finally collapses down to the bottom of the mantle, which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab-plume interactions.展开更多
Hainan Island is a seismic active region, where Qiongshan M7.5 earthquake occurred in 1605 and several seismic belts appeared in recent years, especially the NS trending seismic belt （NSB） located in the northeast p...Hainan Island is a seismic active region, where Qiongshan M7.5 earthquake occurred in 1605 and several seismic belts appeared in recent years, especially the NS trending seismic belt （NSB） located in the northeast part of the island. Here is also a magmatic active region. The lava from about 100 volcanoes covered more than 4000 km^2. The latest eruptions occurred on Ma＇anling-Lei Huling volcanoes within 10,000 years. The neotectonic movement has been determined by geological method in the island and its adjacent areas. In the paper, the present-day 3D crustal movement is obtained by using Global Positioning System （GPS） data observed from 2009 to 2014 and leveling observations measured in 1970s and 1990s respectively. The results show the horizontal movement is mainly along SEE direction relative to the Eurasian Plate. The velocities are between 4.01 and 6.70 mm/a. The tension rate near the NSB is less than I mm/a. The vertical movement shows the island uplifts as a whole with respect to the reference benchmark Xiuyinggang. The average uplifting rate is 2.4 mm/a. The rates are 2-3 mm/a in the northwest and 3-5mm/a in the northwest. It shows the deformation pattern of the southwest island is upward relative to the northeast, which is different from the result inferred from the coastal change and GPS. Haikou and its adjacent region present a subsidence in a long time. The southern part of the middle segment of the Wangwu-Wenjiao fault uplifts relative to the northern. Meanwhile, the western part uplifts relative to the eastern NSB. The vertical crustal motion and the two normal faults nearly correspond to the terrain. The NSB is located along the Puqiangang-Dazhibo fault, which is assessed as a segmented fault with a dip of 80°-90° and party exposed. The 3D deformations and other studies reveal the present activities of earthquakes, volcanoes and the faults. The small earthquakes will still occur in the NS belt and the volcanoes are not active now.展开更多
The mantle xenoliths in the Quaternary ChangbaishanVolcano in southern Jilin Province contain spinel-facies lherzolites. The equilibration temperatures for these samples range from 902℃ to 1064℃ based on the two-pyr...The mantle xenoliths in the Quaternary ChangbaishanVolcano in southern Jilin Province contain spinel-facies lherzolites. The equilibration temperatures for these samples range from 902℃ to 1064℃ based on the two-pyroxene thermometer of Brey and Kohler （1990）, and using the oxybarometry of Nell and Wood （1991）, the oxidation state was estimated from FMQ-1.32 to -0.38 with an average value of FMQ-0.81 （n = 8）, which is comparable to that of abyssal peridotites and the asthenospheric mantle. ThefO2 values of peridotites, together with their bulk rock compositions （e.g., Mg#, Al2O3, CaO, Ni, Co, Cr） and mineral compositions （e.g., Mg# of olivine and pyroxene, Cr# [=Cr/ [Cr＋Al]] and Mg# [=Mg/[Mg＋Fe2~] of spinel）, suggest that the present-day subcontinental lithospheric mantle （SCLM） beneath the Changbaishan Volcano most likely formed from an upwelling asthenosphere at some time after the late Mesozoic and has undergone a low degree of partial melting. The studied lherzolite xenoliths show low concentrations of S, Cu, and platinum group elements （PGE）, which plot a flat pattern on primitive-mantle normalized diagram. Very low concentrations in our samples suggest that PGEs occur as alloys or hosted by silicate and oxide minerals. The compositions of the studied samples are similar to those of peridotite xenoliths in the Longgang volcanic field （LVF） in their mineralogy and bulk rock compositions including the abundance of chalcophile and siderophile elements. However, they are distinctly different from those of peridotite xenoliths in other areas of the North China Craton （NCC） in terms of Cu, S and PGE. Our data suggest that the SCLM underlying the northeastern part of the NCC may represent a distinct unit of the newly formed lithospberic mantle.展开更多
The S wave velocity structure in Changbaishan volcanic region was obtained from teleseismic receiver function modeling. The results show that there exist distinct low velocity layers in crust in volcano area. Beneath ...The S wave velocity structure in Changbaishan volcanic region was obtained from teleseismic receiver function modeling. The results show that there exist distinct low velocity layers in crust in volcano area. Beneath WQD station near to the Tianchi caldera the low velocity layer at 8 km depth is 20 km thick with the lowest S-wave velocity about 2.2 km/s At EDO station located 50 km north of Tianchi caldera, no obvious crustal low velocity layer is detected. In the volcanic region, the thickness of crustal low velocity layer is greater and the lowest velocity is more obvious with the distance shorter to the caldera. It indicates the existence of the high temperature material or magma reservoir in crust near the Tianchi caldera. The receiver functions and inversion result from different back azimuths at CBS permanent seismic station show that the thickness of near surface low velocity layer and Moho depth change with directions. The near surface low velocity layer is obviously thicker in south direction. The Moho depth shows slight uplifting in the direction of the caldera located. We con- sider that the special near surface velocity structure is the main cause of relatively lower prominent frequency of volcanic earthquake waveforms recorded by CBS station. The slight uplifting of Moho beneath Tianchi caldera indicates there is a material exchanging channel between upper mantle and magma reservoir in crust.展开更多
The Ashikule volcanic cluster （AVC） in western Kunlun Mountains is located in a graben region at the convergence of the Altun and Kangxiwa fault zones,and consists of more than 10 main volcanoes and dozens of volcan...The Ashikule volcanic cluster （AVC） in western Kunlun Mountains is located in a graben region at the convergence of the Altun and Kangxiwa fault zones,and consists of more than 10 main volcanoes and dozens of volcanelloes.The Ashi volcano lies in the central part of the volcanic cluster.The lithology,chemical composition and texture of Ashi volcanic rocks were studied in detail,and their implication in magmatic processes was discussed.The phenocrysts in Ashi volcanic rocks consist mainly of plagioclase and pyroxene,and the statistical results of phenocryst contents show that the rocks can be subdivided into two groups.In group A,the content of pyroxene phenocrysts is generally higher than that of plagioclase phenocrysts,but an inverse relation occurs in group B.In TAS diagram,the compositions of both groups fall into the trachyandensite field,but they are obviously concentrated into two clusters.The two clusters exist also in the oxide diagrams.The pyroxene phenocrysts comprise augite,bronzite and hypersthene,and their Mg# histogram shows two peaks.Plagioclase phenocrysts with reaction rim are observed in rocks of both groups.The An values of the core are generally 30-40,and those of the rim are 44-48,which are closer to those of euhedral plagioclases.The bronzites are in equilibrium with the melt,and two sets of magma depths,i.e.,18-25 km and 13-18 km,can be estimated by using thermobarometer proposed by Putirka.The hypersthenes are not in equilibrium with the melt,and can be assigned to xenocrysts.The crystal size distribution （CSD） curves of plagioclase appear as kinked lines indicative of magma mixing.The above analyses show that two magma pockets might exist beneath the Ashi volcano.It is likely that they are connected with each other.The one has more evolved and contains more acidic magma,and the other is a trachyandensite magma pocket characterized by layering.The magma from the upper part of the trachyandensite magma pocket might mix with more acidic magma,resulting in a magma that is more acidic than the magma from the lower part.展开更多
In this paper, we describe three strata at the distal part of the pyroclastic-flow from the Tianchi volcano in 1215 （±15） eruption. One of the strata with crosslayers that are different from typical pyroclastic...In this paper, we describe three strata at the distal part of the pyroclastic-flow from the Tianchi volcano in 1215 （±15） eruption. One of the strata with crosslayers that are different from typical pyroclastic-flow strata may come from a ground-surge. The grain-size and scanning electron microscopy （SEM） analysis was performed to study the origin of the pyroclastic-flow. Characteristics of grain-size distribution show that it is similar with the ash cloud. Through the SEM analyses, we found some quench structures with less damage on the surfaces of the vitric pumices. These phenomena indicate that there has been hydration in the transportation processes at the distal of pyroclastic-flow. It has partly changed the transportation mechanism of pyroclastic-flow, which transitions form dense flow to diluted flow. This paper develops a new distal pyroclastic-flow model in the Tianchi volcano that can be divided into three stages, i.e. the quench stage, expanding stage and depositing stage.展开更多
The Jinlongdingzi active volcano erupted before 1600a, and it is the latest basaltic explosive volcano at Longgang Volcano. Its volcanic products include the Jinlongdingzi volcanic cone (elevation 999.4m), the lava fl...The Jinlongdingzi active volcano erupted before 1600a, and it is the latest basaltic explosive volcano at Longgang Volcano. Its volcanic products include the Jinlongdingzi volcanic cone (elevation 999.4m), the lava flow and the widely\|spread volcanic pyroclastic sheet (Sihai Pyroclastic Sheet). Jinlongdingzi volcanic rocks are trachybasalts with very similar REE patterns and incompatible element patterns, and their \{\{\}\+\{87\}Sr\}/\{\{\}\+\{86\}Sr\} and \{\{\}\+\{143\}Nd\}/\{\{\}\+\{144\}Nd\} ratios range from \{0.704846\} to \{0.704921\} and from \{0.512619\} to \{0.512646\}, respectively. It is revealed that the trachybasalt has the character of primary magma derived directly from mantle sources with very little evolution and crust contamination during its ascending. The younger mantle xenoliths demonstrate that the mantle source of the Jinlongdingzi Volcano is hydrous, with relatively low temperature.展开更多
Three monogenetic cones in the Baossi–Warack area, Ngaoundéré, Adamawa Plateau forming part of the Cameroon Volcanic Line(CVL) are documented in this study. Basaltic lavas(<1 km^3) scattered around these...Three monogenetic cones in the Baossi–Warack area, Ngaoundéré, Adamawa Plateau forming part of the Cameroon Volcanic Line(CVL) are documented in this study. Basaltic lavas(<1 km^3) scattered around these vents and restricted volcaniclastic deposits were emplaced by Hawaiian and mild strombolian style eruptions. The lavas are porphyritic, mainly composed of olivine(chrysolite) and clinopyroxene(diopside and augite) phenocrysts and plagioclase(andesine) microphenocrysts. Accessory minerals include titano-magnetite and titano-hematite, nepheline,apatite and amphibole xenocrysts. Sanidine occurs in some samples and sodi-potassic albite in others. Some olivines and clinopyroxenes exhibit resorbed margins and thin reaction rims while plagioclase displays oscillatory zoning, and sieved textures as a result of magma mixing. Whole-rock geochemistry data indicates that the lavas are silica-undersaturated, composed of basanites and basalts, showing little compositional variations(SiO_2: 39.20 wt.%–48.01 wt.%,MgO: 5.29 wt.%–9.70 wt.%). Trace elements patterns of these lavas suggest they are enriched in LILE including Pb,probably due to crustal contamination. REE patterns suggest cogenetic magmas below Baossi 1 and Baossi 2 volcanoes,and distinct sources below Warack volcano and nearby lavas.The lavas studied show affinity to high-μ(HIMU), enriched type Ⅰ(EM1) and Oceanic Island Basalt(OIB)-like mantle signatures and thus indicate a heterogeneous mantle source underneath the vents as noted at other monogenetic and polygenetic volcanoes along the CVL. Primary melts derived from low degrees of partial melting(0.5%–2%) and encountered low rates of fractionation, and crustal contamination coupled with magma mixing. These melts evolved independently through structural weaknesses in the basement.展开更多
High entropy alloys(HEAs)have been the star materials in electrocatalysis research in recent years.One of their key features is the greatly increased multiplicity of active sites compared to conventional catalytic mat...High entropy alloys(HEAs)have been the star materials in electrocatalysis research in recent years.One of their key features is the greatly increased multiplicity of active sites compared to conventional catalytic materials.This increased multiplicity stimulates a cocktail effect and a scaling-relation breaking effect,and results in improved activity.However,the multiplicity of active sites in HEAs also poses new problems for mechanistic studies.One apparent problem is the inapplicability to HEA catalysts of the currently most popular mechanistic study method,which uses the electrocatalytic theoretical framework(ETF)based on the computational hydrogen electrode(CHE).The ETF uses a single adsorption energy to represent the catalyst,i.e.,a catalyst is represented by a'point'in the volcanic relationship.It naturally does not involve the multiplicity of active sites of a catalyst,and hence loses brevity in expressing the cocktail effect and scaling-relation breaking effect in HEA catalysis.This paper attempts to solve this inapplicability.Based on the fact that the adsorption energy distribution of HEAs is close to a normal distribution,the mean and variance of the adsorption energy distribution are introduced as descriptors of the ETF,replacing the original single adsorption energy.A quantitative relationship between the variance and the cocktail and scaling-relation braking effects is established.We believe the method described in this work will make the ETF more effective in mechanistic studies of HEA electrocatalysis.展开更多
An experiment was conducted to evaluate whether supplementation with a probiotic could enhance digestion and reduce mortality in the volcano rabbit in captivity. Two enclosures at Chapultepec Zoo, Mexico（114 individu...An experiment was conducted to evaluate whether supplementation with a probiotic could enhance digestion and reduce mortality in the volcano rabbit in captivity. Two enclosures at Chapultepec Zoo, Mexico（114 individuals） were used in a crossover design（two periods of 60 days） with the following treatments： control group and supplementation with Saccharomyces cerevisiae（2×108 CFU/exhibit/day）. Supplementation with the probiotic negatively affected（P〈0.01） the digestibility of dry matter, organic matter, neutral detergent fiber（NDF） and energy. Mortality increased（P〈0.04） following supplementation with the probiotic（4.26% vs. 8.89%）, primarily in the juvenile rabbits. The results indicate that yeast supplementation in the volcano rabbit negatively affects digestion and mortality in captivity.展开更多
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.
基金partially supported by Grant-in-aid for Scientific Research(Kiban-B.11440134,Kiban-A 17204037) from Japan Society for the Promotion of Science and by some financial support from the Global Center of Excellence(G-COE) program of Tohoku University
文摘We synthesize significant recent results on the deep structure and origin of the active volcanoes in China's Mainland. Magmatism in the western Pacific arc and back-arc areas is caused by dehydration of the subducting slab and by corner flow in the mantle wedge, whereas the intraplate magmatism in China has different origins. The active volcanoes in Northeast China （such as the Changbai and Wudalianchi） are caused by hot upwelling in the big mantle wedge （BMW） above the stagnant slab in the mantle transition zone and deep slab dehydration as well. The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate （or Indian plate）. The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs＇ deep subduction in the east and the Indian slab＇s deep subduction in the west down to the lower mantle. The stagnant slab finally collapses down to the bottom of the mantle, which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab-plume interactions.
基金supported by the National Natural Science Foundation of China(41372345)
文摘Hainan Island is a seismic active region, where Qiongshan M7.5 earthquake occurred in 1605 and several seismic belts appeared in recent years, especially the NS trending seismic belt （NSB） located in the northeast part of the island. Here is also a magmatic active region. The lava from about 100 volcanoes covered more than 4000 km^2. The latest eruptions occurred on Ma＇anling-Lei Huling volcanoes within 10,000 years. The neotectonic movement has been determined by geological method in the island and its adjacent areas. In the paper, the present-day 3D crustal movement is obtained by using Global Positioning System （GPS） data observed from 2009 to 2014 and leveling observations measured in 1970s and 1990s respectively. The results show the horizontal movement is mainly along SEE direction relative to the Eurasian Plate. The velocities are between 4.01 and 6.70 mm/a. The tension rate near the NSB is less than I mm/a. The vertical movement shows the island uplifts as a whole with respect to the reference benchmark Xiuyinggang. The average uplifting rate is 2.4 mm/a. The rates are 2-3 mm/a in the northwest and 3-5mm/a in the northwest. It shows the deformation pattern of the southwest island is upward relative to the northeast, which is different from the result inferred from the coastal change and GPS. Haikou and its adjacent region present a subsidence in a long time. The southern part of the middle segment of the Wangwu-Wenjiao fault uplifts relative to the northern. Meanwhile, the western part uplifts relative to the eastern NSB. The vertical crustal motion and the two normal faults nearly correspond to the terrain. The NSB is located along the Puqiangang-Dazhibo fault, which is assessed as a segmented fault with a dip of 80°-90° and party exposed. The 3D deformations and other studies reveal the present activities of earthquakes, volcanoes and the faults. The small earthquakes will still occur in the NS belt and the volcanoes are not active now.
基金supported by grants from National Natural Science Foundation of China (Nos.40873016,41173034,90814003)supportedby a grant from China Geological Survey (No.1212011121088)
文摘The mantle xenoliths in the Quaternary ChangbaishanVolcano in southern Jilin Province contain spinel-facies lherzolites. The equilibration temperatures for these samples range from 902℃ to 1064℃ based on the two-pyroxene thermometer of Brey and Kohler （1990）, and using the oxybarometry of Nell and Wood （1991）, the oxidation state was estimated from FMQ-1.32 to -0.38 with an average value of FMQ-0.81 （n = 8）, which is comparable to that of abyssal peridotites and the asthenospheric mantle. ThefO2 values of peridotites, together with their bulk rock compositions （e.g., Mg#, Al2O3, CaO, Ni, Co, Cr） and mineral compositions （e.g., Mg# of olivine and pyroxene, Cr# [=Cr/ [Cr＋Al]] and Mg# [=Mg/[Mg＋Fe2~] of spinel）, suggest that the present-day subcontinental lithospheric mantle （SCLM） beneath the Changbaishan Volcano most likely formed from an upwelling asthenosphere at some time after the late Mesozoic and has undergone a low degree of partial melting. The studied lherzolite xenoliths show low concentrations of S, Cu, and platinum group elements （PGE）, which plot a flat pattern on primitive-mantle normalized diagram. Very low concentrations in our samples suggest that PGEs occur as alloys or hosted by silicate and oxide minerals. The compositions of the studied samples are similar to those of peridotite xenoliths in the Longgang volcanic field （LVF） in their mineralogy and bulk rock compositions including the abundance of chalcophile and siderophile elements. However, they are distinctly different from those of peridotite xenoliths in other areas of the North China Craton （NCC） in terms of Cu, S and PGE. Our data suggest that the SCLM underlying the northeastern part of the NCC may represent a distinct unit of the newly formed lithospberic mantle.
基金supported by National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China (2006BAC01B04)Joint Seismological Science Foundation of China (106023)Contribution No. is 09FE3006 of Institute of Geophysics,China Earthquake Administration
文摘The S wave velocity structure in Changbaishan volcanic region was obtained from teleseismic receiver function modeling. The results show that there exist distinct low velocity layers in crust in volcano area. Beneath WQD station near to the Tianchi caldera the low velocity layer at 8 km depth is 20 km thick with the lowest S-wave velocity about 2.2 km/s At EDO station located 50 km north of Tianchi caldera, no obvious crustal low velocity layer is detected. In the volcanic region, the thickness of crustal low velocity layer is greater and the lowest velocity is more obvious with the distance shorter to the caldera. It indicates the existence of the high temperature material or magma reservoir in crust near the Tianchi caldera. The receiver functions and inversion result from different back azimuths at CBS permanent seismic station show that the thickness of near surface low velocity layer and Moho depth change with directions. The near surface low velocity layer is obviously thicker in south direction. The Moho depth shows slight uplifting in the direction of the caldera located. We con- sider that the special near surface velocity structure is the main cause of relatively lower prominent frequency of volcanic earthquake waveforms recorded by CBS station. The slight uplifting of Moho beneath Tianchi caldera indicates there is a material exchanging channel between upper mantle and magma reservoir in crust.
基金supported by the Special Fund for China Earthquake Research (Grant No. 201008004)Special Fund of State Public Institute for Basic Research (Grant No. IGCEA1307 and IGCEA1101)
文摘The Ashikule volcanic cluster （AVC） in western Kunlun Mountains is located in a graben region at the convergence of the Altun and Kangxiwa fault zones,and consists of more than 10 main volcanoes and dozens of volcanelloes.The Ashi volcano lies in the central part of the volcanic cluster.The lithology,chemical composition and texture of Ashi volcanic rocks were studied in detail,and their implication in magmatic processes was discussed.The phenocrysts in Ashi volcanic rocks consist mainly of plagioclase and pyroxene,and the statistical results of phenocryst contents show that the rocks can be subdivided into two groups.In group A,the content of pyroxene phenocrysts is generally higher than that of plagioclase phenocrysts,but an inverse relation occurs in group B.In TAS diagram,the compositions of both groups fall into the trachyandensite field,but they are obviously concentrated into two clusters.The two clusters exist also in the oxide diagrams.The pyroxene phenocrysts comprise augite,bronzite and hypersthene,and their Mg# histogram shows two peaks.Plagioclase phenocrysts with reaction rim are observed in rocks of both groups.The An values of the core are generally 30-40,and those of the rim are 44-48,which are closer to those of euhedral plagioclases.The bronzites are in equilibrium with the melt,and two sets of magma depths,i.e.,18-25 km and 13-18 km,can be estimated by using thermobarometer proposed by Putirka.The hypersthenes are not in equilibrium with the melt,and can be assigned to xenocrysts.The crystal size distribution （CSD） curves of plagioclase appear as kinked lines indicative of magma mixing.The above analyses show that two magma pockets might exist beneath the Ashi volcano.It is likely that they are connected with each other.The one has more evolved and contains more acidic magma,and the other is a trachyandensite magma pocket characterized by layering.The magma from the upper part of the trachyandensite magma pocket might mix with more acidic magma,resulting in a magma that is more acidic than the magma from the lower part.
基金supported by the National Science Foundation Project(Grant No.40972209)Special Fund of State Public Institute for Basic Research(Grant No.IGCEA 1101)
文摘In this paper, we describe three strata at the distal part of the pyroclastic-flow from the Tianchi volcano in 1215 （±15） eruption. One of the strata with crosslayers that are different from typical pyroclastic-flow strata may come from a ground-surge. The grain-size and scanning electron microscopy （SEM） analysis was performed to study the origin of the pyroclastic-flow. Characteristics of grain-size distribution show that it is similar with the ash cloud. Through the SEM analyses, we found some quench structures with less damage on the surfaces of the vitric pumices. These phenomena indicate that there has been hydration in the transportation processes at the distal of pyroclastic-flow. It has partly changed the transportation mechanism of pyroclastic-flow, which transitions form dense flow to diluted flow. This paper develops a new distal pyroclastic-flow model in the Tianchi volcano that can be divided into three stages, i.e. the quench stage, expanding stage and depositing stage.
文摘The Jinlongdingzi active volcano erupted before 1600a, and it is the latest basaltic explosive volcano at Longgang Volcano. Its volcanic products include the Jinlongdingzi volcanic cone (elevation 999.4m), the lava flow and the widely\|spread volcanic pyroclastic sheet (Sihai Pyroclastic Sheet). Jinlongdingzi volcanic rocks are trachybasalts with very similar REE patterns and incompatible element patterns, and their \{\{\}\+\{87\}Sr\}/\{\{\}\+\{86\}Sr\} and \{\{\}\+\{143\}Nd\}/\{\{\}\+\{144\}Nd\} ratios range from \{0.704846\} to \{0.704921\} and from \{0.512619\} to \{0.512646\}, respectively. It is revealed that the trachybasalt has the character of primary magma derived directly from mantle sources with very little evolution and crust contamination during its ascending. The younger mantle xenoliths demonstrate that the mantle source of the Jinlongdingzi Volcano is hydrous, with relatively low temperature.
基金financially supported by the Ministry of Higher Education, Cameroon, through the Special Allocation for the Modernization of Research (SAMR) granted to the first author
文摘Three monogenetic cones in the Baossi–Warack area, Ngaoundéré, Adamawa Plateau forming part of the Cameroon Volcanic Line(CVL) are documented in this study. Basaltic lavas(<1 km^3) scattered around these vents and restricted volcaniclastic deposits were emplaced by Hawaiian and mild strombolian style eruptions. The lavas are porphyritic, mainly composed of olivine(chrysolite) and clinopyroxene(diopside and augite) phenocrysts and plagioclase(andesine) microphenocrysts. Accessory minerals include titano-magnetite and titano-hematite, nepheline,apatite and amphibole xenocrysts. Sanidine occurs in some samples and sodi-potassic albite in others. Some olivines and clinopyroxenes exhibit resorbed margins and thin reaction rims while plagioclase displays oscillatory zoning, and sieved textures as a result of magma mixing. Whole-rock geochemistry data indicates that the lavas are silica-undersaturated, composed of basanites and basalts, showing little compositional variations(SiO_2: 39.20 wt.%–48.01 wt.%,MgO: 5.29 wt.%–9.70 wt.%). Trace elements patterns of these lavas suggest they are enriched in LILE including Pb,probably due to crustal contamination. REE patterns suggest cogenetic magmas below Baossi 1 and Baossi 2 volcanoes,and distinct sources below Warack volcano and nearby lavas.The lavas studied show affinity to high-μ(HIMU), enriched type Ⅰ(EM1) and Oceanic Island Basalt(OIB)-like mantle signatures and thus indicate a heterogeneous mantle source underneath the vents as noted at other monogenetic and polygenetic volcanoes along the CVL. Primary melts derived from low degrees of partial melting(0.5%–2%) and encountered low rates of fractionation, and crustal contamination coupled with magma mixing. These melts evolved independently through structural weaknesses in the basement.
文摘High entropy alloys(HEAs)have been the star materials in electrocatalysis research in recent years.One of their key features is the greatly increased multiplicity of active sites compared to conventional catalytic materials.This increased multiplicity stimulates a cocktail effect and a scaling-relation breaking effect,and results in improved activity.However,the multiplicity of active sites in HEAs also poses new problems for mechanistic studies.One apparent problem is the inapplicability to HEA catalysts of the currently most popular mechanistic study method,which uses the electrocatalytic theoretical framework(ETF)based on the computational hydrogen electrode(CHE).The ETF uses a single adsorption energy to represent the catalyst,i.e.,a catalyst is represented by a'point'in the volcanic relationship.It naturally does not involve the multiplicity of active sites of a catalyst,and hence loses brevity in expressing the cocktail effect and scaling-relation breaking effect in HEA catalysis.This paper attempts to solve this inapplicability.Based on the fact that the adsorption energy distribution of HEAs is close to a normal distribution,the mean and variance of the adsorption energy distribution are introduced as descriptors of the ETF,replacing the original single adsorption energy.A quantitative relationship between the variance and the cocktail and scaling-relation braking effects is established.We believe the method described in this work will make the ETF more effective in mechanistic studies of HEA electrocatalysis.
文摘An experiment was conducted to evaluate whether supplementation with a probiotic could enhance digestion and reduce mortality in the volcano rabbit in captivity. Two enclosures at Chapultepec Zoo, Mexico（114 individuals） were used in a crossover design（two periods of 60 days） with the following treatments： control group and supplementation with Saccharomyces cerevisiae（2×108 CFU/exhibit/day）. Supplementation with the probiotic negatively affected（P〈0.01） the digestibility of dry matter, organic matter, neutral detergent fiber（NDF） and energy. Mortality increased（P〈0.04） following supplementation with the probiotic（4.26% vs. 8.89%）, primarily in the juvenile rabbits. The results indicate that yeast supplementation in the volcano rabbit negatively affects digestion and mortality in captivity.
