2003 Vol. 28, No. 3
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2003, 28(3): 235-240.
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Abstract:
In the eastern part of the North China block, the refractory peridotite xenoliths in Cenozoic Hebi basalts (Henan Province) are regarded as the shallow relics of the cratonic mantle; while the fertile peridotite xenoliths in Cenozoic Shanwang basalts (Shandong Province) are regarded as the newly accreted mantle. In this paper, a comparison is made between the major and trace elements of the whole rocks and the major elements of the component minerals and the trace elements of the diopsides. The results show that Hebi "cratonic" peridotites and Shanwang "oceanic" ones, respectively, represent the products of 15%-25% and 1%-5% of fractional melting for the primary mantle. These products were metasomated by the silicate carbonatite melt. The mantle metasomatism in the former is stronger than that in the latter. The solidus temperature of the cratonic lithospheric peridotite fell due to the long-term metasomatism of the mantle molten/fluid bodies. The melt underplated at the basement of the lower crust, created the crust-mantle transition zone and resulting in the huge heat and material exchange. The ensuing decreased temperature after Eogene period resulted in the uplifted asthenospheric cooling and underplating at the lithospheric basement for the newly accreted lithosphere. Therefore, the Mesozoic-Cenozoic (relative to Paleozoic) lithospheric thinning did not initiate the simple decrease in lithospheric thickness arising from the asthenospheric upwelling. Instead, this thinning created the replacement process of the accompanying cratonic mantle by the newly accreted one.
In the eastern part of the North China block, the refractory peridotite xenoliths in Cenozoic Hebi basalts (Henan Province) are regarded as the shallow relics of the cratonic mantle; while the fertile peridotite xenoliths in Cenozoic Shanwang basalts (Shandong Province) are regarded as the newly accreted mantle. In this paper, a comparison is made between the major and trace elements of the whole rocks and the major elements of the component minerals and the trace elements of the diopsides. The results show that Hebi "cratonic" peridotites and Shanwang "oceanic" ones, respectively, represent the products of 15%-25% and 1%-5% of fractional melting for the primary mantle. These products were metasomated by the silicate carbonatite melt. The mantle metasomatism in the former is stronger than that in the latter. The solidus temperature of the cratonic lithospheric peridotite fell due to the long-term metasomatism of the mantle molten/fluid bodies. The melt underplated at the basement of the lower crust, created the crust-mantle transition zone and resulting in the huge heat and material exchange. The ensuing decreased temperature after Eogene period resulted in the uplifted asthenospheric cooling and underplating at the lithospheric basement for the newly accreted lithosphere. Therefore, the Mesozoic-Cenozoic (relative to Paleozoic) lithospheric thinning did not initiate the simple decrease in lithospheric thickness arising from the asthenospheric upwelling. Instead, this thinning created the replacement process of the accompanying cratonic mantle by the newly accreted one.
2003, 28(3): 241-249.
Abstract:
The present rock association of the UHP terrane in Dabie-Sulu region, China results from the result of source UHP rocks rebuilt by retrogressive metamorphism, tectonics, anatexis during the exhumation. The dynamics of reformation is the conversion of tectonics, basal erosion and delimitation by means of metamorphism, structure-replacement and anatexis. The UHP terrane is composed of ecologite, marble, jadeite-quartzite, amphibolites, gneisses and foliated granites. In terms of geology and geochemistry, the amphibolite is found to have evolved from ecologite by retrogressive metamorphism and gneisses, foliated granite to have evolved from the amphibolite by anatexis. The anatexis started at 230 Ma when the UHP terrane exhumed to the low crust and turned intense in the middle-low crust. The melting composition from the anatexis of amphibolite is equal to tantalite or granodiorite (in agreement with gneisses). Moreover, the melt from the partial-melting of gneisses with A-type granite composition (which is the same with the foliated granite). The gneisses and foliated granites have both evolved from ecologite by retrogressive metamorphism and delivery anatexis.
The present rock association of the UHP terrane in Dabie-Sulu region, China results from the result of source UHP rocks rebuilt by retrogressive metamorphism, tectonics, anatexis during the exhumation. The dynamics of reformation is the conversion of tectonics, basal erosion and delimitation by means of metamorphism, structure-replacement and anatexis. The UHP terrane is composed of ecologite, marble, jadeite-quartzite, amphibolites, gneisses and foliated granites. In terms of geology and geochemistry, the amphibolite is found to have evolved from ecologite by retrogressive metamorphism and gneisses, foliated granite to have evolved from the amphibolite by anatexis. The anatexis started at 230 Ma when the UHP terrane exhumed to the low crust and turned intense in the middle-low crust. The melting composition from the anatexis of amphibolite is equal to tantalite or granodiorite (in agreement with gneisses). Moreover, the melt from the partial-melting of gneisses with A-type granite composition (which is the same with the foliated granite). The gneisses and foliated granites have both evolved from ecologite by retrogressive metamorphism and delivery anatexis.
2003, 28(3): 250-254.
Abstract:
The North China and Yangtze cratons, the most important tectonic units of China, finally coalesced via collision with the formation of the E-W-trending Qinling Mountains. The North Qinling and South Qinling belts constitute the southern active margin of the North China craton and northern China passive margin of the Yangtze craton, respectively. Both the North China and Yangtze cratons and the North Qinling belt, characterized by a relatively uniform, non-evolutionary composition of clastic sediments in post-Archean La-Th-Sc-Co system, can be distinguished from each other in provenance in terms of La/Co, La/Sc, Th/Co, Th/Sc ratios. Systematic chemical compositions are analyzed (by ICP-MS ELAN 6100 DRC) for Cretaceous to Meso-Proterozoic sediments from the Yangtze craton. The REE patterns of these clastic sedimentary rocks are similar to those of the global typical sedimentary rocks such as PAAS, NASC, ES and the global upper continental crust (UC).The Silurian and Devonian pelites are characteristic of North Qinling belt with high La/Co, La/Sc, Th/Co, Th/Sc ratios. The value of δ (Eu) is sensitive to the mafic material. When the mafic material become a kind of provenance, the value of δ (Eu) changes from 0.61-0.62 to 0.68-0.69, showing that the Yangtze craton accreted to the North Qinling on the southern margin of North China cratons in the Silurian-Devonian period.
The North China and Yangtze cratons, the most important tectonic units of China, finally coalesced via collision with the formation of the E-W-trending Qinling Mountains. The North Qinling and South Qinling belts constitute the southern active margin of the North China craton and northern China passive margin of the Yangtze craton, respectively. Both the North China and Yangtze cratons and the North Qinling belt, characterized by a relatively uniform, non-evolutionary composition of clastic sediments in post-Archean La-Th-Sc-Co system, can be distinguished from each other in provenance in terms of La/Co, La/Sc, Th/Co, Th/Sc ratios. Systematic chemical compositions are analyzed (by ICP-MS ELAN 6100 DRC) for Cretaceous to Meso-Proterozoic sediments from the Yangtze craton. The REE patterns of these clastic sedimentary rocks are similar to those of the global typical sedimentary rocks such as PAAS, NASC, ES and the global upper continental crust (UC).The Silurian and Devonian pelites are characteristic of North Qinling belt with high La/Co, La/Sc, Th/Co, Th/Sc ratios. The value of δ (Eu) is sensitive to the mafic material. When the mafic material become a kind of provenance, the value of δ (Eu) changes from 0.61-0.62 to 0.68-0.69, showing that the Yangtze craton accreted to the North Qinling on the southern margin of North China cratons in the Silurian-Devonian period.
2003, 28(3): 255-260.
Abstract:
This paper analyzes the chemical composition and physical properties of three star corundum specimens based on routine gemmological tests, electronic probe analysis and ultraviolet-visible spectrum analysis. In addition, the authors analyze the origin of star corundum. The observations show that the tested three specimens appear orange-red, brownish red and mauve and have relatively high transparency. Under strong reflected light, these three specimens exhibit cloudy surface features. The star lines from the surface of the stones are diffused and curved. At the intersection of the star lines, a bright light area can be seen. Through a microscope, these three specimens show well-developed pits and mocks. Two specimens show poorly-defined fibrous aluminum titanate inclusions, but one shows melted surface. All of these features indicate that the fibrous aluminum titanate inclusions seen in these three specimens may be produced by diffusion at a high temperature but annealing after being synthesized. All of these three specimens show obvious closed-arranged curved growth striations, indicating an origin of flame fusion. The electronic probe analysis results, absorption spectrum observations and ultraviolet-visible spectrum analysis give a Cr coloring element for these three specimens. Therefore, these three specimens should be named star ruby, and the color is caused by the synthesis but diffusion origin. However, the asterism is caused by the reflection from fibrous aluminum titanate inclusions produced by diffusion.
This paper analyzes the chemical composition and physical properties of three star corundum specimens based on routine gemmological tests, electronic probe analysis and ultraviolet-visible spectrum analysis. In addition, the authors analyze the origin of star corundum. The observations show that the tested three specimens appear orange-red, brownish red and mauve and have relatively high transparency. Under strong reflected light, these three specimens exhibit cloudy surface features. The star lines from the surface of the stones are diffused and curved. At the intersection of the star lines, a bright light area can be seen. Through a microscope, these three specimens show well-developed pits and mocks. Two specimens show poorly-defined fibrous aluminum titanate inclusions, but one shows melted surface. All of these features indicate that the fibrous aluminum titanate inclusions seen in these three specimens may be produced by diffusion at a high temperature but annealing after being synthesized. All of these three specimens show obvious closed-arranged curved growth striations, indicating an origin of flame fusion. The electronic probe analysis results, absorption spectrum observations and ultraviolet-visible spectrum analysis give a Cr coloring element for these three specimens. Therefore, these three specimens should be named star ruby, and the color is caused by the synthesis but diffusion origin. However, the asterism is caused by the reflection from fibrous aluminum titanate inclusions produced by diffusion.
2003, 28(3): 261-267.
Abstract:
This paper analyzes both from the ecozone divisions of shell fauna including Kinnella-Plectothyrella zone (< BA3), Draborthis-Toxorthis zone (BA3-4) and Paromalomena-Aegiromena zone (BA4-5) or some other elements (indicating ecospheres of < BA3 or > BA4-5), and from the combination of the lithology of rock containing these shell faunas, sedimentary, the differentiation features inside the Yangtze ocean basin that could be divided into central deep-water basin with black siliceous shale (> BA4-5), eastern neritic clastic basin (mainly in BA4-5) and western neritic carbonate rock-clastic rock (mainly in < BA3) parts. This paper also probes the changes of water-depth from south to north in the above-mentioned parts of the Yangtze basin. In the central basin, from south to north, the Yangtze basin became deeper and deeper, indicating that, in the south it is deeper from BA4-5 and in the north, much deeper from BA4-5, with the depositional center located in Hubei and the middle of Hunan. In the western basin, from south to north, the Yangtze basin became deeper, that is, in the northern Guizhou and eastern Sichuan, the corresponding ecozone was located in < BA3, and in the northern Sichuan and southern part of Shaanxi, the ecozone is located in BA4. In the eastern basin, from south to north, the Yangtze basin also became deeper and deeper, for example, in Tonglu and Changshan, the corresponding ecozone is located in < BA3, while in Jingxian and Nanjing, it is located in ≥BA4-5.
This paper analyzes both from the ecozone divisions of shell fauna including Kinnella-Plectothyrella zone (< BA3), Draborthis-Toxorthis zone (BA3-4) and Paromalomena-Aegiromena zone (BA4-5) or some other elements (indicating ecospheres of < BA3 or > BA4-5), and from the combination of the lithology of rock containing these shell faunas, sedimentary, the differentiation features inside the Yangtze ocean basin that could be divided into central deep-water basin with black siliceous shale (> BA4-5), eastern neritic clastic basin (mainly in BA4-5) and western neritic carbonate rock-clastic rock (mainly in < BA3) parts. This paper also probes the changes of water-depth from south to north in the above-mentioned parts of the Yangtze basin. In the central basin, from south to north, the Yangtze basin became deeper and deeper, indicating that, in the south it is deeper from BA4-5 and in the north, much deeper from BA4-5, with the depositional center located in Hubei and the middle of Hunan. In the western basin, from south to north, the Yangtze basin became deeper, that is, in the northern Guizhou and eastern Sichuan, the corresponding ecozone was located in < BA3, and in the northern Sichuan and southern part of Shaanxi, the ecozone is located in BA4. In the eastern basin, from south to north, the Yangtze basin also became deeper and deeper, for example, in Tonglu and Changshan, the corresponding ecozone is located in < BA3, while in Jingxian and Nanjing, it is located in ≥BA4-5.
2003, 28(3): 268-274.
Abstract:
DF1-1 diapir is one of the most active areas with the overpressure fluid in Yinggehai basin. The overpressure fluids were controlled by the structural stress and migration system made up of different types of fractures and faults. In terms of the large-scale vertical and episodic fluid flows in the diaper area, the dynamics of the fluid flows is mainly attributed both to the vertical pressure difference and to the local stress fields (including thermal stress field) caused by the changes in infiltration flow field from fluid flow. The relationship between structure and fluid flow in the diaper area thus obtained in this paper is employed to simulate, together with the finite element digital method, the evolutions of both the structural stress fields and the infiltration fluid filed that are in line with the process of diapirism. The results show that the stress fields and fluid migration fields before diapirism are different from those after it. As a whole, stress fields from the tectonic stress determined the fluid migrating pattern along the fault zone in the DF1-1 diapir, that is, the fluids migrating from both sides of the diapir to its center and migrating upward from the diapir. Thermal stresses caused by the high-pressure fluid flow also controlled the local stress pattern and petroleum and gas fluid flow direction, which drove the matured hydrocarbon fluid migration upward from depression to highland. Too great a thermal stress value might have changed the stress pattern and the general trend of the petroleum and gas migration.
DF1-1 diapir is one of the most active areas with the overpressure fluid in Yinggehai basin. The overpressure fluids were controlled by the structural stress and migration system made up of different types of fractures and faults. In terms of the large-scale vertical and episodic fluid flows in the diaper area, the dynamics of the fluid flows is mainly attributed both to the vertical pressure difference and to the local stress fields (including thermal stress field) caused by the changes in infiltration flow field from fluid flow. The relationship between structure and fluid flow in the diaper area thus obtained in this paper is employed to simulate, together with the finite element digital method, the evolutions of both the structural stress fields and the infiltration fluid filed that are in line with the process of diapirism. The results show that the stress fields and fluid migration fields before diapirism are different from those after it. As a whole, stress fields from the tectonic stress determined the fluid migrating pattern along the fault zone in the DF1-1 diapir, that is, the fluids migrating from both sides of the diapir to its center and migrating upward from the diapir. Thermal stresses caused by the high-pressure fluid flow also controlled the local stress pattern and petroleum and gas fluid flow direction, which drove the matured hydrocarbon fluid migration upward from depression to highland. Too great a thermal stress value might have changed the stress pattern and the general trend of the petroleum and gas migration.
2003, 28(3): 275-280.
Abstract:
The balanced geological section has been widely used for the analysis of orogenic belt, but it is infrequent for extensional basins. In this paper, 4 extensional balanced geological section analysis were practiced in Fuyu oil layer of Liangjing, Jilin oilfield, southern Songliao basin with the technology and method, including deformation history restoration, decompaction and erosion restoration. The structure of different ages and the continuous sedimentary sections have been restored. The results show that the structural styles possess the characteristics of negative flower structure in the shallow level and extensional detachment in deep level. The parameters, including fault growth index, the basin extensional history and fault detachment depth, indicate that Late Cretaceous is an important stage for the structure transferring mainly with a strike-slip style before this time and an extensional structure and detachment after this time. Therefore, a basin model with twin dynamic property and back-arc characters is proposed.
The balanced geological section has been widely used for the analysis of orogenic belt, but it is infrequent for extensional basins. In this paper, 4 extensional balanced geological section analysis were practiced in Fuyu oil layer of Liangjing, Jilin oilfield, southern Songliao basin with the technology and method, including deformation history restoration, decompaction and erosion restoration. The structure of different ages and the continuous sedimentary sections have been restored. The results show that the structural styles possess the characteristics of negative flower structure in the shallow level and extensional detachment in deep level. The parameters, including fault growth index, the basin extensional history and fault detachment depth, indicate that Late Cretaceous is an important stage for the structure transferring mainly with a strike-slip style before this time and an extensional structure and detachment after this time. Therefore, a basin model with twin dynamic property and back-arc characters is proposed.
2003, 28(3): 281-288.
Abstract:
Detailed geochemical analysis has been carried out on reservoir extracts from the Es 3 reservoir of the Leng 43 block of the Lengdong oilfield, Liaohe basin. Bulk compositions and aliphatic biomarker parameters indicate that these residual oils from three different oil columns are biodegraded at varying degrees. The biodegradation degree increases from the top of oil columns to the bottom of oil columns with excellent gredient variations. Comparison of the distributions of trimethylnaphthalenes (TMNs), tetramethylnaphthalenes (TeMNs) and pentamethylnaphthalenes (PMNs) at various biodegradation levels indicate that biodegradation controls their occurrence and distribution. The susceptibility of individual isomer of TMNs, TeMNs and PMNs to biodegradation has been determined on its relative abundance variation during biodegradation. The results show that these thermal dynamic stable structures are more susceptible to bacterial attack than these thermal unstable structures, suggesting biodegradation completely differs from thermal dynamic process. This study reveals that after moderate biodegradation these maturity parameters based on thermal stability of isomers are invalid and the ratios between easily biodegraded and refractory structures, in turn, can be used as new geochemical indicators to assess the degree of biodegradation.
Detailed geochemical analysis has been carried out on reservoir extracts from the Es 3 reservoir of the Leng 43 block of the Lengdong oilfield, Liaohe basin. Bulk compositions and aliphatic biomarker parameters indicate that these residual oils from three different oil columns are biodegraded at varying degrees. The biodegradation degree increases from the top of oil columns to the bottom of oil columns with excellent gredient variations. Comparison of the distributions of trimethylnaphthalenes (TMNs), tetramethylnaphthalenes (TeMNs) and pentamethylnaphthalenes (PMNs) at various biodegradation levels indicate that biodegradation controls their occurrence and distribution. The susceptibility of individual isomer of TMNs, TeMNs and PMNs to biodegradation has been determined on its relative abundance variation during biodegradation. The results show that these thermal dynamic stable structures are more susceptible to bacterial attack than these thermal unstable structures, suggesting biodegradation completely differs from thermal dynamic process. This study reveals that after moderate biodegradation these maturity parameters based on thermal stability of isomers are invalid and the ratios between easily biodegraded and refractory structures, in turn, can be used as new geochemical indicators to assess the degree of biodegradation.
2003, 28(3): 289-296.
Abstract:
Abundant sedimentary marks of allochthonous genesis are present in the extra-thick coalbeds both in Xianfeng basin and in Xiaolongtan basin in Yunnan. These genesis indicators reveal two new submodels about allochthonous accumulation: Xianfeng submodel and Xiaolongtan submodel. Xianfeng submodel can be reduced to the twice accumulation of lacustrine peaty fan delta and underwater gravity flow, and Xiaolongtan submodel can be reduced to the twice accumulation of lacustrine peaty delta and underwater gravity flow. Integrating these two submodels with Fuxin submodel and Fushun submodel previously established by the authors of this paper, a complete allochthonous-hypautochthony twice lacustrine combination accumulation model for the extra-thick coalbeds in Chinese Mesozoic and Cenozoic intracontinental fault basin is thus established, as shown below: the river distant transport of humic-peat detritus → the sedimentation of peaty fan delta or peaty delta + the allochthonous sedimentation of lacustrine drift peat + the hypautochthony accumulation of local lakeshore swamp peat + the autochthonous accumulation of local lacustrine algae peat + the sedimentation fine detritus, medium-macro-grained detritus or biostromal shelly detritus → the mix and transportation because of flood current or weak storm flow or underwater gravity flow → the mechanical differentiation and resedimentation of peat and inorganic detritus.
Abundant sedimentary marks of allochthonous genesis are present in the extra-thick coalbeds both in Xianfeng basin and in Xiaolongtan basin in Yunnan. These genesis indicators reveal two new submodels about allochthonous accumulation: Xianfeng submodel and Xiaolongtan submodel. Xianfeng submodel can be reduced to the twice accumulation of lacustrine peaty fan delta and underwater gravity flow, and Xiaolongtan submodel can be reduced to the twice accumulation of lacustrine peaty delta and underwater gravity flow. Integrating these two submodels with Fuxin submodel and Fushun submodel previously established by the authors of this paper, a complete allochthonous-hypautochthony twice lacustrine combination accumulation model for the extra-thick coalbeds in Chinese Mesozoic and Cenozoic intracontinental fault basin is thus established, as shown below: the river distant transport of humic-peat detritus → the sedimentation of peaty fan delta or peaty delta + the allochthonous sedimentation of lacustrine drift peat + the hypautochthony accumulation of local lakeshore swamp peat + the autochthonous accumulation of local lacustrine algae peat + the sedimentation fine detritus, medium-macro-grained detritus or biostromal shelly detritus → the mix and transportation because of flood current or weak storm flow or underwater gravity flow → the mechanical differentiation and resedimentation of peat and inorganic detritus.
2003, 28(3): 297-300.
Abstract:
It is a common phenomenon that the structural heights in the overburden and substrate evaporite layers are not in agreement with each other in the salt tectonic areas. Two kinds of relationships between structural heights in the overburden evaporite and those in the substrate evaporite in the forelands, where evaporite experienced the deformation, were established in line with the differences both in the boundary stress states and in the rock rheology. When an orogenic wedge underthrusts the evaporite-bearing foreland basin fill, the troughs of overburden synclines will directly match the peaks of substrate anticlines. When an orogenic wedge overrides the evaporite-bearing foreland basin fill, the back-limbs of overburden anticlines will match the peaks of substrate anticlines, and the peaks of overburden anticlines will match the front-limbs of substrate anticlines. Finally, the discussion of the petroleum implication for the two relationships was based on the petroleum exploration in Kuqa foreland.
It is a common phenomenon that the structural heights in the overburden and substrate evaporite layers are not in agreement with each other in the salt tectonic areas. Two kinds of relationships between structural heights in the overburden evaporite and those in the substrate evaporite in the forelands, where evaporite experienced the deformation, were established in line with the differences both in the boundary stress states and in the rock rheology. When an orogenic wedge underthrusts the evaporite-bearing foreland basin fill, the troughs of overburden synclines will directly match the peaks of substrate anticlines. When an orogenic wedge overrides the evaporite-bearing foreland basin fill, the back-limbs of overburden anticlines will match the peaks of substrate anticlines, and the peaks of overburden anticlines will match the front-limbs of substrate anticlines. Finally, the discussion of the petroleum implication for the two relationships was based on the petroleum exploration in Kuqa foreland.
2003, 28(3): 301-305.
Abstract:
Gaolong Carlin type gold deposit is situated in the nucleus of the Gaolong arch in the western section of the Xilin-Baise fault-fold zone. The ore bodies are placed in the contact of the Carboniferous-Permian carbonites and the Triassic turbidites. The Baise-Gaolong Guzhang regional large-scale faults and their secondary structures form the passages for the flow of the mineralizing fluid and the spaces for the precipitation of the mineralized materials. There are four types of normal alkanes in the Gaolong ore district: the normal maturation type in the non-mineralized strata, and the abnormal maturation type, the hydrothermal solution type and the microbial degradation type in the ore bodies. These normal alkanes offer the favourable mineralization information and have the tracer significance for the gold mineralization.
Gaolong Carlin type gold deposit is situated in the nucleus of the Gaolong arch in the western section of the Xilin-Baise fault-fold zone. The ore bodies are placed in the contact of the Carboniferous-Permian carbonites and the Triassic turbidites. The Baise-Gaolong Guzhang regional large-scale faults and their secondary structures form the passages for the flow of the mineralizing fluid and the spaces for the precipitation of the mineralized materials. There are four types of normal alkanes in the Gaolong ore district: the normal maturation type in the non-mineralized strata, and the abnormal maturation type, the hydrothermal solution type and the microbial degradation type in the ore bodies. These normal alkanes offer the favourable mineralization information and have the tracer significance for the gold mineralization.
2003, 28(3): 306-314.
Abstract:
The development of the seismic database of China and its adjacent areas is introduced in the first part of this paper. Based on the combination of the difference between western and eastern parts of China on plate tectonics, stress state and structure of crust-mantle, the authors analyze the spatial pattern of strong earthquakes from aspects of the whole dataset, historical seismic records, instrumental records and hypocenter depth. It is found that before 1900 DC, North China presented the great trapeziform pattern. After 1900 DC, the west part of China was characterized by the huge sector, with the deepest regions of foci located in the two vertices of the huge sector, namely Xingdukushi-Pamier region and the area along the border of India and Burma. Then, the linear and regional migrating modes are summarized according to the spatial pattern of strong earthquakes in China. Detailedly, the linear migration can be subdivided into two modes, straight jumping and pendulum. The mechanisms of all types of migrating modes are briefly discussed based on the models of fault fracture, spring-block, structural difference between crust and mantle and their relative movement as well.
The development of the seismic database of China and its adjacent areas is introduced in the first part of this paper. Based on the combination of the difference between western and eastern parts of China on plate tectonics, stress state and structure of crust-mantle, the authors analyze the spatial pattern of strong earthquakes from aspects of the whole dataset, historical seismic records, instrumental records and hypocenter depth. It is found that before 1900 DC, North China presented the great trapeziform pattern. After 1900 DC, the west part of China was characterized by the huge sector, with the deepest regions of foci located in the two vertices of the huge sector, namely Xingdukushi-Pamier region and the area along the border of India and Burma. Then, the linear and regional migrating modes are summarized according to the spatial pattern of strong earthquakes in China. Detailedly, the linear migration can be subdivided into two modes, straight jumping and pendulum. The mechanisms of all types of migrating modes are briefly discussed based on the models of fault fracture, spring-block, structural difference between crust and mantle and their relative movement as well.
2003, 28(3): 315-322.
Abstract:
The real geological medium is extremely complicated. Elastic wave theory based on homogeneous and continuous medium model may lead to incorrect explanation of seismic response to geological structure and may even lead to erroneous explanation. Such useful seismic information may be eliminated because it is considered as the noise without an accurate constitutive equation closer to true medium. Natural rock-soil media consist of large porous blocks as a dispersive medium with various gaps, fractures and joint contact surfaces. Hence, that kind of medium is a mixed field of dispersive porous blocks and named "discrete media" by the authors. Among the blocks, pore fluid could run through along all kinds of gaps or surfaces. Also, in the porous blocks, the oil could be filled in pores. Therefore, a global mathematical model of constitutive relation is derived in this paper to simulate the wave propagation in the discrete media.
The real geological medium is extremely complicated. Elastic wave theory based on homogeneous and continuous medium model may lead to incorrect explanation of seismic response to geological structure and may even lead to erroneous explanation. Such useful seismic information may be eliminated because it is considered as the noise without an accurate constitutive equation closer to true medium. Natural rock-soil media consist of large porous blocks as a dispersive medium with various gaps, fractures and joint contact surfaces. Hence, that kind of medium is a mixed field of dispersive porous blocks and named "discrete media" by the authors. Among the blocks, pore fluid could run through along all kinds of gaps or surfaces. Also, in the porous blocks, the oil could be filled in pores. Therefore, a global mathematical model of constitutive relation is derived in this paper to simulate the wave propagation in the discrete media.
2003, 28(3): 323-326.
Abstract:
FEM is used to modeling IP sounding on 3-D geoelectric section. First, this paper presents the 3-D boundary value and variation equation of point-source electrical field on a 3-D structure. Then, the boundary condition for the infinite boundary is simplified to improve calculation speed and precision. On this basis, the partial derivatives matrix for the ratio between the apparent resistivity and the model resistivity parameters is calculated, and at the same time, the IP on 3-D geoelectric section is positively simulated. Compared with equivalent resistivity method, this simulation saves much calculation time. The test of several relative typical geoelectric models shows that this modeling method is correct and feasible.
FEM is used to modeling IP sounding on 3-D geoelectric section. First, this paper presents the 3-D boundary value and variation equation of point-source electrical field on a 3-D structure. Then, the boundary condition for the infinite boundary is simplified to improve calculation speed and precision. On this basis, the partial derivatives matrix for the ratio between the apparent resistivity and the model resistivity parameters is calculated, and at the same time, the IP on 3-D geoelectric section is positively simulated. Compared with equivalent resistivity method, this simulation saves much calculation time. The test of several relative typical geoelectric models shows that this modeling method is correct and feasible.
2003, 28(3): 327-332.
Abstract:
This paper analyzes the concentrations of organic matter, the group components, the compositions and distribution of aliphatics and polycyclic aromatic hydrocarbons (PAHs) from the atmospheric particulates in the Shougang district, Beijing. More than 40 kinds of PAHs from the atmospheric particulates have been detected, nine of which are precedence-controlled pollutants set by US EPA. Many PAHs are carcinogenic and mutated. According to the biomarkers, the organic pollutants come mainly from the incomplete combustion of coal, partly from the emission of automobile wastes. The coal can result in more grave pollution in the Shougang district than the petroleum during the incomplete combustion.
This paper analyzes the concentrations of organic matter, the group components, the compositions and distribution of aliphatics and polycyclic aromatic hydrocarbons (PAHs) from the atmospheric particulates in the Shougang district, Beijing. More than 40 kinds of PAHs from the atmospheric particulates have been detected, nine of which are precedence-controlled pollutants set by US EPA. Many PAHs are carcinogenic and mutated. According to the biomarkers, the organic pollutants come mainly from the incomplete combustion of coal, partly from the emission of automobile wastes. The coal can result in more grave pollution in the Shougang district than the petroleum during the incomplete combustion.
2003, 28(3): 333-336.
Abstract:
This paper discusses the impact mechanisms and positive-negative effects of urbanization on groundwater quality based on a three-year study in Shijiazhuang by quantitative calculation and analysis of urbanization level and groundwater pollution. The results show that growth of urbanization is helpful to improve the groundwater quality, but may easily result in salt pollution. It puts forward a kind of theory and a radical way of sustainable development for those cities, dependent on groundwater for their main, or even all, water supply.
This paper discusses the impact mechanisms and positive-negative effects of urbanization on groundwater quality based on a three-year study in Shijiazhuang by quantitative calculation and analysis of urbanization level and groundwater pollution. The results show that growth of urbanization is helpful to improve the groundwater quality, but may easily result in salt pollution. It puts forward a kind of theory and a radical way of sustainable development for those cities, dependent on groundwater for their main, or even all, water supply.
2003, 28(3): 337-340.
Abstract:
In order to study the affecting factors in the degradation of chlorinated hydrocarbon, tetrachlrethene (PCE) was selected as target contaminant and Ni/Fe bimetal was used as reactants in batch experiments. The results show: (1) When the mass of Ni/Fe bimetal used in batch experiment was 10 g and 20 g, the reaction rates (kobs) were 0.047 7 h-1 and 0.09 7 h-1, respectively. The more the Ni/Fe bimetal used in PCE degradation, the faster the reaction. (2) The reaction rates (kobs) were 0.047 7 h-1, 0.059 8 h-1 and 0.088 6 h-1 when Ni/Fe bimetal was 20-40 mesh, 40-65 mesh and 80-100 mesh, respectively. The finer the metal, the faster the reaction. (3) The reaction rates (kobs) were 0.047 7 h-1, 0.066 2 h-1 and 0.073 4 h-1 when the Ni/Fe mass ratio was 0.024%, 0.048% and 0.072%, respectively. The higher the Ni/Fe mass ratio, the faster the reaction. Further study of the optimum Ni/Fe mass ratio is needed.
In order to study the affecting factors in the degradation of chlorinated hydrocarbon, tetrachlrethene (PCE) was selected as target contaminant and Ni/Fe bimetal was used as reactants in batch experiments. The results show: (1) When the mass of Ni/Fe bimetal used in batch experiment was 10 g and 20 g, the reaction rates (kobs) were 0.047 7 h-1 and 0.09 7 h-1, respectively. The more the Ni/Fe bimetal used in PCE degradation, the faster the reaction. (2) The reaction rates (kobs) were 0.047 7 h-1, 0.059 8 h-1 and 0.088 6 h-1 when Ni/Fe bimetal was 20-40 mesh, 40-65 mesh and 80-100 mesh, respectively. The finer the metal, the faster the reaction. (3) The reaction rates (kobs) were 0.047 7 h-1, 0.066 2 h-1 and 0.073 4 h-1 when the Ni/Fe mass ratio was 0.024%, 0.048% and 0.072%, respectively. The higher the Ni/Fe mass ratio, the faster the reaction. Further study of the optimum Ni/Fe mass ratio is needed.
2003, 28(3): 341-345.
Abstract:
Epi-karst dynamic system is related closely with CO2 content in soil. Temperature and rainfall dominate the seasonal change of CO2 content in soil. The CO2 content is low in winter when it is cold and dry while it is high in summer as it is hot and wet. There are a hypo-trough and a hypo-crest in autumn when there is a sudden increasing in rainfall. Epi-karst dynamic system is more active from spring to summer than from autumn to winter, because rainfall is focus in spring and summer. The system transfers more and more carbon with the increase of CO2 content in soil from winter to summer. With the control of CO2 content and temperature, the sedimentation-dissolution trend of the system changes from sedimentation trend to dissolution trend from winter to spring and summer.
Epi-karst dynamic system is related closely with CO2 content in soil. Temperature and rainfall dominate the seasonal change of CO2 content in soil. The CO2 content is low in winter when it is cold and dry while it is high in summer as it is hot and wet. There are a hypo-trough and a hypo-crest in autumn when there is a sudden increasing in rainfall. Epi-karst dynamic system is more active from spring to summer than from autumn to winter, because rainfall is focus in spring and summer. The system transfers more and more carbon with the increase of CO2 content in soil from winter to summer. With the control of CO2 content and temperature, the sedimentation-dissolution trend of the system changes from sedimentation trend to dissolution trend from winter to spring and summer.
2003, 28(3): 346-350.
Abstract:
The reconstruction of the paleotectonic pattern in geologic history period is one of the important contents of basin modeling and also the basis for the research into the tectonic evolution history of basin and oil and gas migration path simulation. Therefore, this reconstruction is important for oil-gas-bearing basin research. Integrating geographic information system (GIS) technique with the basin analysis method, this paper has made a research into the structural evolutionary history of paleo-central uplift belt, northern Songliao basin, illustrated the principle and method for basin GIS-based paleotectonic reconstruction, reconstructed successfully the paleotectonic framework of paleo-central uplift belt, and epitomized the structural evolutionary history of paleo-central uplift belt. The result shows that the paleo-central uplift belt began to develop in the early Huoshiling-Yingcheng period, reached its peak during the Denglouku period, started to shrink gradually in the Quantou period, and ceased its growth at the end of the Yaojia period. From the point of view of the matching relation between major oil and gas migration period and structural formation period, the paleo-central uplift belt is believed to be a favorable site of natural gas accumulation.
The reconstruction of the paleotectonic pattern in geologic history period is one of the important contents of basin modeling and also the basis for the research into the tectonic evolution history of basin and oil and gas migration path simulation. Therefore, this reconstruction is important for oil-gas-bearing basin research. Integrating geographic information system (GIS) technique with the basin analysis method, this paper has made a research into the structural evolutionary history of paleo-central uplift belt, northern Songliao basin, illustrated the principle and method for basin GIS-based paleotectonic reconstruction, reconstructed successfully the paleotectonic framework of paleo-central uplift belt, and epitomized the structural evolutionary history of paleo-central uplift belt. The result shows that the paleo-central uplift belt began to develop in the early Huoshiling-Yingcheng period, reached its peak during the Denglouku period, started to shrink gradually in the Quantou period, and ceased its growth at the end of the Yaojia period. From the point of view of the matching relation between major oil and gas migration period and structural formation period, the paleo-central uplift belt is believed to be a favorable site of natural gas accumulation.
2003, 28(3): 351-355.
Abstract:
Data mining from field rock spectrums is important for hyper-spectral remote sensing modeling. The characteristics of the field spectrum data are used to reform and combine evolutionary strategies with CHC (cross generation elitist selection, heterogeneous recombination and cataclysm mutation) and to design a genetic algorithm to conduct rock spectrum discrimination: to build a linear discriminating equation with many variables (wavelength intervals). Floating encoding is used for the coefficients of the equation (genes). Two optimization objectives are compared with each other: one is to maximize the right-judgment ratio of known samples, and the other is to minimize the ratio of in-class versus between-class distances. The results show that the former is briefer and faster while both of them are effective. Monte Carlo sampling is employed to adjust searching spaces. Uniform and Gaussian distribution models are employed to produce new-generation genes, showing that the former model has better performance, because the genes have various unknown distributions. An experimental study is presented based on the data of 1 823 wavelength intervals from Beiya gold deposit, Yunnan, China, obtained with the FieldSpectr Fr equipment (ASD Co. US). The algorithm proves high efficiency in identification of altered dolomitic limestone, a potentially gold-bearing rock, from other rocks.
Data mining from field rock spectrums is important for hyper-spectral remote sensing modeling. The characteristics of the field spectrum data are used to reform and combine evolutionary strategies with CHC (cross generation elitist selection, heterogeneous recombination and cataclysm mutation) and to design a genetic algorithm to conduct rock spectrum discrimination: to build a linear discriminating equation with many variables (wavelength intervals). Floating encoding is used for the coefficients of the equation (genes). Two optimization objectives are compared with each other: one is to maximize the right-judgment ratio of known samples, and the other is to minimize the ratio of in-class versus between-class distances. The results show that the former is briefer and faster while both of them are effective. Monte Carlo sampling is employed to adjust searching spaces. Uniform and Gaussian distribution models are employed to produce new-generation genes, showing that the former model has better performance, because the genes have various unknown distributions. An experimental study is presented based on the data of 1 823 wavelength intervals from Beiya gold deposit, Yunnan, China, obtained with the FieldSpectr Fr equipment (ASD Co. US). The algorithm proves high efficiency in identification of altered dolomitic limestone, a potentially gold-bearing rock, from other rocks.
2003, 28(3): 357-360.
Abstract:
A practical detection scheme with JCXA-733 EPMA-based micro-ultraviolet visible cathodoluminescence has been constructed to analyze both invisible and visible luminescence phenomena for the micro-area surface of solid samples. The wavelength and intensity of the luminescence depend largely on composition, crystal structure and crystal defection of the materials, and also on the growth conditions, growth processes and the environmental conditions where occur the materials. Ultraviolet and ultra-infrared detection of samples will yield more inherent information over broad waveband. Application of this method to the analysis of the source for quartz detritus and of the generation relation between micro rims of secondary enlargement quartz in glauconite-bearing quartz sandstone from Tangshan region, Hebei Province, reveals both the distinct features of ultraviolet luminescence and the radiate-damnification-induced color center at 287 nm wavelength. Hence, it can be deduced that this sandstone experienced two generations of cementation and that its quartz detritus were derived from complex sources. This technique provides a new tool for the investigation into the detritus sources and cementation histories for clasonites and shows a great significance for the analysis of sedimentary basins, oil and gas reservoir.
A practical detection scheme with JCXA-733 EPMA-based micro-ultraviolet visible cathodoluminescence has been constructed to analyze both invisible and visible luminescence phenomena for the micro-area surface of solid samples. The wavelength and intensity of the luminescence depend largely on composition, crystal structure and crystal defection of the materials, and also on the growth conditions, growth processes and the environmental conditions where occur the materials. Ultraviolet and ultra-infrared detection of samples will yield more inherent information over broad waveband. Application of this method to the analysis of the source for quartz detritus and of the generation relation between micro rims of secondary enlargement quartz in glauconite-bearing quartz sandstone from Tangshan region, Hebei Province, reveals both the distinct features of ultraviolet luminescence and the radiate-damnification-induced color center at 287 nm wavelength. Hence, it can be deduced that this sandstone experienced two generations of cementation and that its quartz detritus were derived from complex sources. This technique provides a new tool for the investigation into the detritus sources and cementation histories for clasonites and shows a great significance for the analysis of sedimentary basins, oil and gas reservoir.
