The vertical structure of the crustal block of the Songliao Basin can be divided into upper, middle and low Earth's crust according to density. There is an about 3-km-thick low density interval between the upper c...The vertical structure of the crustal block of the Songliao Basin can be divided into upper, middle and low Earth's crust according to density. There is an about 3-km-thick low density interval between the upper crust and the middle crust. This interval may be a magma chamber accumulated in crust by 'fluid phase' which is precipitated and separated from upper mantle meltmass. The abiogenetic natural gas, other gaseous mass and hydrothermal fluids are provided to the Songliao rifted basin through crustal faults and natural earthquakes. This is a basic condition to form an abiogenetic gas reservoir in the Songliao Basin. On both flanks of the upper crust (or named basin basement) fault there are structural traps in and above the basement and unconformity surface or lateral extended sand, which contains communicated pores, as migration pathway and natural gas reservoir; up to gas reservoirs there is shale as enclosed cap rock, and the suitable arrangement of these conditions is the basic features of abiogenetic gas reservoir.展开更多
Reactions between a boninitic or basaltic magma and harzburgite at shallow mantle depths are thought to be closely related to the formation of podiform chromitites,but little experimental data is available on these re...Reactions between a boninitic or basaltic magma and harzburgite at shallow mantle depths are thought to be closely related to the formation of podiform chromitites,but little experimental data is available on these reactions.In this study,a series of experiments were conducted at 1.5GPa and 1 000–1 400 oC to investigate the interactions between boninitic magma and harzburgite in homogenous mixed systems with varied bulk concentrations of water(~0.7 wt.%–10 wt.%)and Cr2O3(~0.2 wt.%–4 wt.%).In the experimental charges,chromite grains can be observed coexisting with orthopyroxene,clinopyroxene±olivine,and quenched melt in the Cr-bearing systems.The bulk concentration of Cr2O3 in the starting material has a slight effect on compositional changes in the chromites generated.However,the Cr#(Cr#=100×Cr/(Cr+Al))and Mg#(Mg#=100×Mg/(Mg+Fe))values for the chromites exhibit positive and negative correlations,respectively,with the bulk H2O concentrations.At 1 100 oC,chromite Cr#values range from^33–35 to^58–65,and chromite Mg#values range from^70–73 to^55–58when bulk H2O contents in the starting material are increased from^0.7 wt.%to^10 wt.%.The experimentally produced chromites have compositions(as expressed by Cr#,Mg#,and Ni O and Mn O contents)similar to natural chromites from low-Cr#chromitite bodies.We suggest that the interactions between boninitic magmas with varied H2O contents and harzburgite in a shallow mantle wedge could be a possible mechanism that forms the low-Cr#chromitites found in ophiolites.We emphasize here that H2O may play an important role in the compositional evolutions of natural chromitites.展开更多
The evolution of the upward migration of the magma is a nonlinear and unstable problem in mathematics. It is difficult to solve it. And using the numerical method, the solution is relatively tedious and time-consuming...The evolution of the upward migration of the magma is a nonlinear and unstable problem in mathematics. It is difficult to solve it. And using the numerical method, the solution is relatively tedious and time-consuming. This paper introduces a method of the instantaneous point source to solve the linear and unstable heat conduction equation during the infinite period of time instead of the solution of the nonlinear and unstable heat conduction equation. The results obtained by this method coincide with those by the numerical method, meaning that this method offers a simple way to solve the nonlinear and unstable heat conduction equation.展开更多
The fluid mechanics of dike emplacement are analyzed using the translatory wave theory. The stress strain relations in the host rock are assumed linear and the fracture resistance of the host rock is assumed small. Th...The fluid mechanics of dike emplacement are analyzed using the translatory wave theory. The stress strain relations in the host rock are assumed linear and the fracture resistance of the host rock is assumed small. The resulting model is a flowing dyke progressing upwards to the surface with constant speed and a very small side slope. Apart from the topmost section, the form of the dyke is very close to the static form corresponding to the magma pressure in a no-flow situation. Two scales are found that control the flow, a width scale and a composite stiffness parameter for the host rock, representing the properties of the rock and the magma such as elasticity and viscosity. The theory explains a number of special features for dykes that are already known by researchers. It also adds two new points, the most interesting being that the composite stiffness of the rock can be estimated from field observations of the downwards widening angle of the dyke.展开更多
Dongguashan deposit is a large porphyry-skarn copper（gold） deposit in Tongling ore district. The Qingshanjiao intermediate acid intrusion of Yanshanian had a direct genetic relationship with mineralization. The magm...Dongguashan deposit is a large porphyry-skarn copper（gold） deposit in Tongling ore district. The Qingshanjiao intermediate acid intrusion of Yanshanian had a direct genetic relationship with mineralization. The magma origin, rock-forming dynamic background and rock-forming process were studied, and the rock-forming mechanism of Qingshanjiao intrusion was discussed, based on geological characteristics, detailed observation of petrography and systematic investigation of petrochemistry, trace elements and REE geochemistry characteristics of Qingshanjiao intrusion. The results show that Qingshanjiao rock body belongs to high-K calc-alkaline series with higher LREE elements, Th, Rb and Sr abundance, but depleted in HREE elements, Ba, Nb and Ta. The primary magma originated from the mantle-crust mixtures which were caused by basaltic magma of mantle mixing with syenite magma of partial melting of the lower crust, and the formation environment of Qingshanjiao intrusion was emplaced in the transitional environment from compression to extension. The Harker diagram and hybrid structures of plagioclase and potassium feldspar indicate that the fractional crystallization occurred in the process of magmatic evolution. The petrochemistry, trace elements and REE geochemistry characteristics indicate that the magma was contaminated by crustal material during the rock-forming. These results suggested that the Qingshanjiao intrusion was formed by fractional crystallization and assimilation and hybridization of mantle-crust magma in the transitional environment from compression to extensional.展开更多
The research on the widely distributed Ghina granite in Mesozoic and Genozoic geological background shows that there are three kinds of material source, i. e. the crustal type in southern China granite, the transition...The research on the widely distributed Ghina granite in Mesozoic and Genozoic geological background shows that there are three kinds of material source, i. e. the crustal type in southern China granite, the transitional type of migmatization of mantle展开更多
The Quaternary basalt in south Leizhou Peninsula and north Hainan Island is the largest Cenozoic basalt in area in Southern China. In north Hainan Island its distribution covers up to 4000 km^2. Many researchers have ...The Quaternary basalt in south Leizhou Peninsula and north Hainan Island is the largest Cenozoic basalt in area in Southern China. In north Hainan Island its distribution covers up to 4000 km^2. Many researchers have studied its age of eruption, sequence of activity and area of distribution by different approaches and have sug-展开更多
基金Project supported by the National Natural Science Foundation of China
文摘The vertical structure of the crustal block of the Songliao Basin can be divided into upper, middle and low Earth's crust according to density. There is an about 3-km-thick low density interval between the upper crust and the middle crust. This interval may be a magma chamber accumulated in crust by 'fluid phase' which is precipitated and separated from upper mantle meltmass. The abiogenetic natural gas, other gaseous mass and hydrothermal fluids are provided to the Songliao rifted basin through crustal faults and natural earthquakes. This is a basic condition to form an abiogenetic gas reservoir in the Songliao Basin. On both flanks of the upper crust (or named basin basement) fault there are structural traps in and above the basement and unconformity surface or lateral extended sand, which contains communicated pores, as migration pathway and natural gas reservoir; up to gas reservoirs there is shale as enclosed cap rock, and the suitable arrangement of these conditions is the basic features of abiogenetic gas reservoir.
基金supported by the National Programme on Global Change and Air-Sea Interaction (No. GASI-GEOGE-02)the National Nature Science Foundation of China (Nos. 41772040,91858104)the Fundamental Research Funds for the Central Universities,Hohai University (No. 2013/B18020030)。
文摘Reactions between a boninitic or basaltic magma and harzburgite at shallow mantle depths are thought to be closely related to the formation of podiform chromitites,but little experimental data is available on these reactions.In this study,a series of experiments were conducted at 1.5GPa and 1 000–1 400 oC to investigate the interactions between boninitic magma and harzburgite in homogenous mixed systems with varied bulk concentrations of water(~0.7 wt.%–10 wt.%)and Cr2O3(~0.2 wt.%–4 wt.%).In the experimental charges,chromite grains can be observed coexisting with orthopyroxene,clinopyroxene±olivine,and quenched melt in the Cr-bearing systems.The bulk concentration of Cr2O3 in the starting material has a slight effect on compositional changes in the chromites generated.However,the Cr#(Cr#=100×Cr/(Cr+Al))and Mg#(Mg#=100×Mg/(Mg+Fe))values for the chromites exhibit positive and negative correlations,respectively,with the bulk H2O concentrations.At 1 100 oC,chromite Cr#values range from^33–35 to^58–65,and chromite Mg#values range from^70–73 to^55–58when bulk H2O contents in the starting material are increased from^0.7 wt.%to^10 wt.%.The experimentally produced chromites have compositions(as expressed by Cr#,Mg#,and Ni O and Mn O contents)similar to natural chromites from low-Cr#chromitite bodies.We suggest that the interactions between boninitic magmas with varied H2O contents and harzburgite in a shallow mantle wedge could be a possible mechanism that forms the low-Cr#chromitites found in ophiolites.We emphasize here that H2O may play an important role in the compositional evolutions of natural chromitites.
文摘The evolution of the upward migration of the magma is a nonlinear and unstable problem in mathematics. It is difficult to solve it. And using the numerical method, the solution is relatively tedious and time-consuming. This paper introduces a method of the instantaneous point source to solve the linear and unstable heat conduction equation during the infinite period of time instead of the solution of the nonlinear and unstable heat conduction equation. The results obtained by this method coincide with those by the numerical method, meaning that this method offers a simple way to solve the nonlinear and unstable heat conduction equation.
文摘The fluid mechanics of dike emplacement are analyzed using the translatory wave theory. The stress strain relations in the host rock are assumed linear and the fracture resistance of the host rock is assumed small. The resulting model is a flowing dyke progressing upwards to the surface with constant speed and a very small side slope. Apart from the topmost section, the form of the dyke is very close to the static form corresponding to the magma pressure in a no-flow situation. Two scales are found that control the flow, a width scale and a composite stiffness parameter for the host rock, representing the properties of the rock and the magma such as elasticity and viscosity. The theory explains a number of special features for dykes that are already known by researchers. It also adds two new points, the most interesting being that the composite stiffness of the rock can be estimated from field observations of the downwards widening angle of the dyke.
基金Project(20091100704)supported by the Special Funds for Scientific Research of Land and Natural Resources,ChinaProject(2015CX008)supported by the Innovation Driven Plan of Central South University,China
文摘Dongguashan deposit is a large porphyry-skarn copper（gold） deposit in Tongling ore district. The Qingshanjiao intermediate acid intrusion of Yanshanian had a direct genetic relationship with mineralization. The magma origin, rock-forming dynamic background and rock-forming process were studied, and the rock-forming mechanism of Qingshanjiao intrusion was discussed, based on geological characteristics, detailed observation of petrography and systematic investigation of petrochemistry, trace elements and REE geochemistry characteristics of Qingshanjiao intrusion. The results show that Qingshanjiao rock body belongs to high-K calc-alkaline series with higher LREE elements, Th, Rb and Sr abundance, but depleted in HREE elements, Ba, Nb and Ta. The primary magma originated from the mantle-crust mixtures which were caused by basaltic magma of mantle mixing with syenite magma of partial melting of the lower crust, and the formation environment of Qingshanjiao intrusion was emplaced in the transitional environment from compression to extension. The Harker diagram and hybrid structures of plagioclase and potassium feldspar indicate that the fractional crystallization occurred in the process of magmatic evolution. The petrochemistry, trace elements and REE geochemistry characteristics indicate that the magma was contaminated by crustal material during the rock-forming. These results suggested that the Qingshanjiao intrusion was formed by fractional crystallization and assimilation and hybridization of mantle-crust magma in the transitional environment from compression to extensional.
文摘The research on the widely distributed Ghina granite in Mesozoic and Genozoic geological background shows that there are three kinds of material source, i. e. the crustal type in southern China granite, the transitional type of migmatization of mantle
文摘The Quaternary basalt in south Leizhou Peninsula and north Hainan Island is the largest Cenozoic basalt in area in Southern China. In north Hainan Island its distribution covers up to 4000 km^2. Many researchers have studied its age of eruption, sequence of activity and area of distribution by different approaches and have sug-
