We quantified the systematic variations in global transform fault morphology,revealing a first-order dependence on the spreading rate.(1)The average age offset of both the full transform and transform sub-segments dec...We quantified the systematic variations in global transform fault morphology,revealing a first-order dependence on the spreading rate.(1)The average age offset of both the full transform and transform sub-segments decrease with increasing spreading rate.(2)The average depth of both the transform valley and adjacent ridges are smaller in the fast compared to the slow systems,reflecting possibly density anomalies associated with warmer mantle at the fast systems and rifting at the slow ridges.However,the average depth difference between the transform valley and adjacent ridges is relatively constant from the fast to slow systems.(3)The nodal basin at a ridge-transform intersection is deeper and dominant at the ultraslow and slow systems,possibly reflecting a lower magma supply and stronger viscous resistance to mantle upwelling near a colder transform wall.In contrast,the nodal high,is most prominent in the fast,intermediate,and hotspot-influenced systems,where robust axial volcanic ridges extend toward the ridge-transform intersection.(4)Statistically,the average transform valley is wider at a transform system of larger age offset,reflecting thicker deforming plates flanking the transform fault.(5)The maximum magnitude of the transform earthquakes increases with age offset owing to an increase in the seismogenic area.Individual transform faults also exhibit significant anomalies owing to the complex local tectonic and magmatic processes.展开更多
Large-scale detachment faults on mid-ocean ridges （MORs） provide a window into the deeper earth. They have megamullion on their corrugated surfaces, with exposed lower crustal and upper mantle rocks, rela- tively hi...Large-scale detachment faults on mid-ocean ridges （MORs） provide a window into the deeper earth. They have megamullion on their corrugated surfaces, with exposed lower crustal and upper mantle rocks, rela- tively high residual Bouguer gravity anomaly and P-wave velocity, and are commonly associated with ocean- ic core complex. According to 30 detachment faults identified on MORs, we found that their distances to the axis mostly range from 5 to 50 km, half-spreading rates range from 6.8 to 17 mm/a, and activity time ranges from recent to 3 Ma. Most of the detachment faults are developed on the slow spreading Mid-Atlantic Ridge （MAR） and ultra-slow spreading Southwest Indian Ridge （SWIRl, with the dominant half-spreading rates of 7-13 mm/a, especially 10-13 mm/a. Furthermore, they mostly occur at the inside corner of one segment end and result in an asymmetric seafloor spreading. The detachment faults on MORs are mainly controlled by the tectonism and influenced by the magmatism. Long-lived detachment faults tend to be formed where the ridge magma supply is at a moderate level, although the tectonism is a first-order controlling factor. At the slow spreading ridges, detachment faults tend to occur where local magma supply is relatively low, whilst at the ultra-slow spreading ridges, they normally occur where local magma supply is relatively high. These faults are accompanied by hydrothermal activities, with their relationships being useful in the study of hydrothermal polymetallic sulfides and their origin.展开更多
The target of this study is to develop a spreading rate regression model capable of predicting rate of spread of Nigerian crude oil spills on water. The major factors responsible for spreading rate of crude oil on wat...The target of this study is to develop a spreading rate regression model capable of predicting rate of spread of Nigerian crude oil spills on water. The major factors responsible for spreading rate of crude oil on water were considered, namely surface tension, viscosity, and specific gravity/American Petroleum Institute degree (<sup>0</sup>API), all at specified temperature values. The surface tension, viscosity and density parameters were interactively measured under controlled factorial analysis. The spreading rate of each crude oil was determined by artificially spilling them on laboratory calm/stagnant water in a rectangular tank and their averages were also computed. These averages were used to develop a regression model equation for spreading rate. The model developed indicated that an average spreading rate was 3.3528 cm/s at 37.5<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C and the predictive regression model is evaluated with the interactions of specific gravity, viscosity and surface tension. It is convenient to state that the model will predict the spread rate of crude oils which possess imputed physicochemical properties having pour point averaged 15.5<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C on calm seawater.展开更多
The regular variations in magmatic activities along the Northwest Pacific plate have been little studied in spite of their importance. In this contribution, systematic analyses were conducted on tholeiitic basalts fro...The regular variations in magmatic activities along the Northwest Pacific plate have been little studied in spite of their importance. In this contribution, systematic analyses were conducted on tholeiitic basalts from three Ocean Drilling Program sites(Sites 304, 1149, and 801), including the petrographic features, major and trace elements, Nd isotopic compositions, and mineral structure and compositions of whole rocks. Volcanic rocks from Sites 304, 1149, and 801 belong to tholeiites and exhibit depleted light rare earth elements(LREE), large ion lithophile elemental contents(LILE), and relatively depleted Nd isotopic ratios(143Nd/144Nd=0.513139-0.513211), similar to those of normal mid-ocean ridge basalts(NMORB). Comprehensive data on mineral compositions, whole-rock geochemistry, and geochronology demonstrate that a regular variation trend exists in the north-south direction along the Northwest Pacific plate. The 143 Nd/144 Nd values(0.513139-0.513211) and trace-element ratios for whole rocks(Sm/Th=15.35-30.00; Zr/Hf=28.53-35.76; Zr/Y=2.58-3.67; Th/La=0.04-0.06; Th/Y=0.33-0.70), as well as the trace-element ratios(Zr/Hf, La/Yb, Ti/Zr) of clinopyroxenes from Sites 1149 and 801 tholeiites show larger variations compared to those from Site 304 tholeiites(143Nd/144Nd=0.513185-0.513195; Sm/Th=18.19-20.58; Zr/Hf=31.07-33.26; Zr/Y=2.62-3.03; Th/La=0.05-0.06; Th/Y=0.48-0.57). Mineral zoning textures were obvious in tholeiites from Sites 1149 and 801 but were rarely observed in Site 304.These regular features were likely attributed to the differences in the heterogeneity of the magma source,the process of magmatic evolution, the plate-spreading rate, and the effective and ineffective mixing.展开更多
This study investigates the international spillover effects of US unconventional monetary policy(UMP)-frequently called large-scale asset purchases or quantitative easing(QE)—on advanced and emerging market economies...This study investigates the international spillover effects of US unconventional monetary policy(UMP)-frequently called large-scale asset purchases or quantitative easing(QE)—on advanced and emerging market economies,using structural vector autoregressive models with high-frequency daily data.Blinder(Federal Reserve Bank of St.Louis Rev 92(6):465–479,2010)argued that the QE measures primarily aim to reduce US interest rate spreads,such as term and risk premiums.Considering this argument and recent empirical evidence,we use two spreads as indicators of US UMP:the mortgage and term spreads.Based on data from 20 emerging and 20 advanced countries,our empirical findings reveal that US unconventional monetary policies significantly affect financial conditions in emerging and advanced countries by altering the risktaking behavior of investors.This result suggests that the risk-taking channel plays an important role in transmitting the effects of these policies to the rest of the world.The extent of these effects depends on the type of QE measures.QE measures such as purchases of private sector securities that lower the US mortgage spread exert stronger and more significant spillover effects on international financial markets than those that reduce the US term spread.Furthermore,the estimated financial spillovers vary substantially across countries and between and within the emerging and advanced countries that we examine in this study.展开更多
Underground fires are a smoldering combustion with a slow spread rate, low temperatures and no flame. They can last from days to several months, and can even become overwintering fires. They are difficult to find, lea...Underground fires are a smoldering combustion with a slow spread rate, low temperatures and no flame. They can last from days to several months, and can even become overwintering fires. They are difficult to find, leading to considerable damage to the forests. The moisture content of combustible fuels is an important factor in the occurrence and persistence of underground forest fires. The Daxing’an Mountains are a hot spot for underground fires in China. This paper looks at the influence of different moisture contents on underground fire characteristics using simulation combustion experiments in the laboratory. The study showed that peak temperature and spread rate fluctuation of humus at different moisture levels increased with humus depth. Peak temperature and spread rate fluctuation of humus at different depths decreased with increased moisture;moisture content and depth of humus had a significant effect on peak temperature and spread rate fluctuation;peak temperature at different depths decreased with increased moisture;the spread rate in upper layers increased with moisture content, while the spread rate in the lower layers decreased with increased moisture content.展开更多
In the Phase Ⅱ Project at the Hefei Light Source, a fourth-harmonic ＂Landau＂ cavity will be operated in order to suppress the coupled-bunch instabilities and increase the beam lifetime of the Hefei storage ring. In...In the Phase Ⅱ Project at the Hefei Light Source, a fourth-harmonic ＂Landau＂ cavity will be operated in order to suppress the coupled-bunch instabilities and increase the beam lifetime of the Hefei storage ring. Instabilities limit the utility of the higher-harmonic cavity when the storage ring is operated with a small momentum compaction. Analytical modeling and simulations show that the instabilities result from Robinson mode coupling. In the analytic modeling, we operate an algorithm to consider the Robinson instabilities. To study the evolution of unstable behavior, simulations have been performed in which macroparticles are distributed among the buckets. Both the analytic modeling and simulations agree for passive operation of the harmonic cavity.展开更多
基金The foundation of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0205the National Natural Science Foundation of China under contract Nos 41976064,41890813,41976066,91958211,and 41706056+4 种基金the scholarship of China Scholarship Councilthe foundations of the Chinese Academy of Sciences under contract Nos Y4SL021001,QYZDY-SSW-DQC005,133244KYSB20180029,and 131551KYSB20200021the National Key Research and Development Program of China under contract Nos 2018YFC0309800 and 2018YFC0310105the Foundation of the China Ocean Mineral Resources Research and Development Association under contract No.DY135-S2-1-04the Guangdong Basic and Applied Basic Research Foundation under contract No.2021A1515012227。
文摘We quantified the systematic variations in global transform fault morphology,revealing a first-order dependence on the spreading rate.(1)The average age offset of both the full transform and transform sub-segments decrease with increasing spreading rate.(2)The average depth of both the transform valley and adjacent ridges are smaller in the fast compared to the slow systems,reflecting possibly density anomalies associated with warmer mantle at the fast systems and rifting at the slow ridges.However,the average depth difference between the transform valley and adjacent ridges is relatively constant from the fast to slow systems.(3)The nodal basin at a ridge-transform intersection is deeper and dominant at the ultraslow and slow systems,possibly reflecting a lower magma supply and stronger viscous resistance to mantle upwelling near a colder transform wall.In contrast,the nodal high,is most prominent in the fast,intermediate,and hotspot-influenced systems,where robust axial volcanic ridges extend toward the ridge-transform intersection.(4)Statistically,the average transform valley is wider at a transform system of larger age offset,reflecting thicker deforming plates flanking the transform fault.(5)The maximum magnitude of the transform earthquakes increases with age offset owing to an increase in the seismogenic area.Individual transform faults also exhibit significant anomalies owing to the complex local tectonic and magmatic processes.
基金The National Natural Science Foundation of China under contract Nos 91028006 and 41206046the Dayang 115 under contact No.DYXM-115-02-3-01
文摘Large-scale detachment faults on mid-ocean ridges （MORs） provide a window into the deeper earth. They have megamullion on their corrugated surfaces, with exposed lower crustal and upper mantle rocks, rela- tively high residual Bouguer gravity anomaly and P-wave velocity, and are commonly associated with ocean- ic core complex. According to 30 detachment faults identified on MORs, we found that their distances to the axis mostly range from 5 to 50 km, half-spreading rates range from 6.8 to 17 mm/a, and activity time ranges from recent to 3 Ma. Most of the detachment faults are developed on the slow spreading Mid-Atlantic Ridge （MAR） and ultra-slow spreading Southwest Indian Ridge （SWIRl, with the dominant half-spreading rates of 7-13 mm/a, especially 10-13 mm/a. Furthermore, they mostly occur at the inside corner of one segment end and result in an asymmetric seafloor spreading. The detachment faults on MORs are mainly controlled by the tectonism and influenced by the magmatism. Long-lived detachment faults tend to be formed where the ridge magma supply is at a moderate level, although the tectonism is a first-order controlling factor. At the slow spreading ridges, detachment faults tend to occur where local magma supply is relatively low, whilst at the ultra-slow spreading ridges, they normally occur where local magma supply is relatively high. These faults are accompanied by hydrothermal activities, with their relationships being useful in the study of hydrothermal polymetallic sulfides and their origin.
文摘The target of this study is to develop a spreading rate regression model capable of predicting rate of spread of Nigerian crude oil spills on water. The major factors responsible for spreading rate of crude oil on water were considered, namely surface tension, viscosity, and specific gravity/American Petroleum Institute degree (<sup>0</sup>API), all at specified temperature values. The surface tension, viscosity and density parameters were interactively measured under controlled factorial analysis. The spreading rate of each crude oil was determined by artificially spilling them on laboratory calm/stagnant water in a rectangular tank and their averages were also computed. These averages were used to develop a regression model equation for spreading rate. The model developed indicated that an average spreading rate was 3.3528 cm/s at 37.5<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C and the predictive regression model is evaluated with the interactions of specific gravity, viscosity and surface tension. It is convenient to state that the model will predict the spread rate of crude oils which possess imputed physicochemical properties having pour point averaged 15.5<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C on calm seawater.
基金supported by the National Natural Science Foundation of China (Grant code: 41476034, 41272369, 40802038, and 41320104006)research funds from State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences (Grant code: 81300001)
文摘The regular variations in magmatic activities along the Northwest Pacific plate have been little studied in spite of their importance. In this contribution, systematic analyses were conducted on tholeiitic basalts from three Ocean Drilling Program sites(Sites 304, 1149, and 801), including the petrographic features, major and trace elements, Nd isotopic compositions, and mineral structure and compositions of whole rocks. Volcanic rocks from Sites 304, 1149, and 801 belong to tholeiites and exhibit depleted light rare earth elements(LREE), large ion lithophile elemental contents(LILE), and relatively depleted Nd isotopic ratios(143Nd/144Nd=0.513139-0.513211), similar to those of normal mid-ocean ridge basalts(NMORB). Comprehensive data on mineral compositions, whole-rock geochemistry, and geochronology demonstrate that a regular variation trend exists in the north-south direction along the Northwest Pacific plate. The 143 Nd/144 Nd values(0.513139-0.513211) and trace-element ratios for whole rocks(Sm/Th=15.35-30.00; Zr/Hf=28.53-35.76; Zr/Y=2.58-3.67; Th/La=0.04-0.06; Th/Y=0.33-0.70), as well as the trace-element ratios(Zr/Hf, La/Yb, Ti/Zr) of clinopyroxenes from Sites 1149 and 801 tholeiites show larger variations compared to those from Site 304 tholeiites(143Nd/144Nd=0.513185-0.513195; Sm/Th=18.19-20.58; Zr/Hf=31.07-33.26; Zr/Y=2.62-3.03; Th/La=0.05-0.06; Th/Y=0.48-0.57). Mineral zoning textures were obvious in tholeiites from Sites 1149 and 801 but were rarely observed in Site 304.These regular features were likely attributed to the differences in the heterogeneity of the magma source,the process of magmatic evolution, the plate-spreading rate, and the effective and ineffective mixing.
基金Funding was provided by Anadolu University Scientific Research Project Commission(Grant number:1605E282).
文摘This study investigates the international spillover effects of US unconventional monetary policy(UMP)-frequently called large-scale asset purchases or quantitative easing(QE)—on advanced and emerging market economies,using structural vector autoregressive models with high-frequency daily data.Blinder(Federal Reserve Bank of St.Louis Rev 92(6):465–479,2010)argued that the QE measures primarily aim to reduce US interest rate spreads,such as term and risk premiums.Considering this argument and recent empirical evidence,we use two spreads as indicators of US UMP:the mortgage and term spreads.Based on data from 20 emerging and 20 advanced countries,our empirical findings reveal that US unconventional monetary policies significantly affect financial conditions in emerging and advanced countries by altering the risktaking behavior of investors.This result suggests that the risk-taking channel plays an important role in transmitting the effects of these policies to the rest of the world.The extent of these effects depends on the type of QE measures.QE measures such as purchases of private sector securities that lower the US mortgage spread exert stronger and more significant spillover effects on international financial markets than those that reduce the US term spread.Furthermore,the estimated financial spillovers vary substantially across countries and between and within the emerging and advanced countries that we examine in this study.
基金financially supported by the National Natural Science Foundation of China (31971669)the Postgraduate Innovation Project of Beihua University (2021-013)
文摘Underground fires are a smoldering combustion with a slow spread rate, low temperatures and no flame. They can last from days to several months, and can even become overwintering fires. They are difficult to find, leading to considerable damage to the forests. The moisture content of combustible fuels is an important factor in the occurrence and persistence of underground forest fires. The Daxing’an Mountains are a hot spot for underground fires in China. This paper looks at the influence of different moisture contents on underground fire characteristics using simulation combustion experiments in the laboratory. The study showed that peak temperature and spread rate fluctuation of humus at different moisture levels increased with humus depth. Peak temperature and spread rate fluctuation of humus at different depths decreased with increased moisture;moisture content and depth of humus had a significant effect on peak temperature and spread rate fluctuation;peak temperature at different depths decreased with increased moisture;the spread rate in upper layers increased with moisture content, while the spread rate in the lower layers decreased with increased moisture content.
基金Supported by National Natural Science Foundation of China(10979045,11175180,11175182)
文摘In the Phase Ⅱ Project at the Hefei Light Source, a fourth-harmonic ＂Landau＂ cavity will be operated in order to suppress the coupled-bunch instabilities and increase the beam lifetime of the Hefei storage ring. Instabilities limit the utility of the higher-harmonic cavity when the storage ring is operated with a small momentum compaction. Analytical modeling and simulations show that the instabilities result from Robinson mode coupling. In the analytic modeling, we operate an algorithm to consider the Robinson instabilities. To study the evolution of unstable behavior, simulations have been performed in which macroparticles are distributed among the buckets. Both the analytic modeling and simulations agree for passive operation of the harmonic cavity.
