2000 Vol. 25, No. 3
Display Method:
2000, 25(3): 221-226.
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Abstract:
A suite of Neo-Archaean tonalitic-trondjemites-granodioritic intrusive rocks composed mainly of diorites, quartz diorites, and tonalites are discovered in Guyang district, Inner Mongolia through the regional mapping. Although these intrusive rocks have been metamorphosed to some extent, their relatively perfect appearances quite different from those of the Archaean gray gneisses can still be observed. These rocks within the calc-alkali series are a part of the TTG rock series. The isotopic dating indicates that the age of the rocks at 2 400-2 500 Ma, i.e. at the end of Neo-Archaean.
A suite of Neo-Archaean tonalitic-trondjemites-granodioritic intrusive rocks composed mainly of diorites, quartz diorites, and tonalites are discovered in Guyang district, Inner Mongolia through the regional mapping. Although these intrusive rocks have been metamorphosed to some extent, their relatively perfect appearances quite different from those of the Archaean gray gneisses can still be observed. These rocks within the calc-alkali series are a part of the TTG rock series. The isotopic dating indicates that the age of the rocks at 2 400-2 500 Ma, i.e. at the end of Neo-Archaean.
2000, 25(3): 227-231.
Abstract:
The deep fault from Linhe to Jining, a complex longterm active fault zone has not been under thorough investigation in terms of its early evolution for the past years. However, in the present research, five tectonic sections in the proportion 1:2 000 are mapped on the basis of the 1:50 000 regional geological surveying. In addition, a great number of micro-structural observations and fabric measurements are completed in the laboratory. The research shows that the evidence of the Neo-Archaean fault is expressed by the high-temperature ductile shear zone of high amphibolite facies-granulite facies that is overprinted by the low-temperature ductile shear zone of the greenschist in the shallow layers after the Lower Proterozoic crust was elevated in the extension system. After the Middle Proterozoic, this ductile shear zone is transformed into brittle fault, controlling deposition and magma formation in different periods.
The deep fault from Linhe to Jining, a complex longterm active fault zone has not been under thorough investigation in terms of its early evolution for the past years. However, in the present research, five tectonic sections in the proportion 1:2 000 are mapped on the basis of the 1:50 000 regional geological surveying. In addition, a great number of micro-structural observations and fabric measurements are completed in the laboratory. The research shows that the evidence of the Neo-Archaean fault is expressed by the high-temperature ductile shear zone of high amphibolite facies-granulite facies that is overprinted by the low-temperature ductile shear zone of the greenschist in the shallow layers after the Lower Proterozoic crust was elevated in the extension system. After the Middle Proterozoic, this ductile shear zone is transformed into brittle fault, controlling deposition and magma formation in different periods.
2000, 25(3): 232-236.
Abstract:
The regional geological mapping in Beishan, Guyang County, Inner Mongolia, indicates the presence of the ductile shear zones in the Neo-Archaean quartz diorite and the Meso-Proterozoic tonalities. The field investigation, strain measurement, indoor micro-structure and electronic probe show that this ductile shear zone occurs as two groups of conjugate combinatorial shear zones. The formation mechanism of this conjugate shear zone, a simple shear that occurred at the end of the Meso-Proterozoic in the falser environment, is related to the compression between the Siberia plate and the North China plate. The metamorphic facies of this conjugate shear zone is the greenschist facies.
The regional geological mapping in Beishan, Guyang County, Inner Mongolia, indicates the presence of the ductile shear zones in the Neo-Archaean quartz diorite and the Meso-Proterozoic tonalities. The field investigation, strain measurement, indoor micro-structure and electronic probe show that this ductile shear zone occurs as two groups of conjugate combinatorial shear zones. The formation mechanism of this conjugate shear zone, a simple shear that occurred at the end of the Meso-Proterozoic in the falser environment, is related to the compression between the Siberia plate and the North China plate. The metamorphic facies of this conjugate shear zone is the greenschist facies.
2000, 25(3): 237-241.
Abstract:
The thrust nappe structural features in the Mount Seerteng are presented in this paper on the basis of the information on the regional geological investigation (1∶50 000), the field work in target areas and the geophysical references on the depth of the earth. Moreover, the detailed analysis of the dynamic mechanism of the nappe structure in this region indicates that the Mount Seerteng is a massive nappe body, and that the major dynamic force for the presence of the large-scale thrust nappe in this region is the action of the local stress field — the elevation of the mantle current system circulating in the opposite directions.
The thrust nappe structural features in the Mount Seerteng are presented in this paper on the basis of the information on the regional geological investigation (1∶50 000), the field work in target areas and the geophysical references on the depth of the earth. Moreover, the detailed analysis of the dynamic mechanism of the nappe structure in this region indicates that the Mount Seerteng is a massive nappe body, and that the major dynamic force for the presence of the large-scale thrust nappe in this region is the action of the local stress field — the elevation of the mantle current system circulating in the opposite directions.
2000, 25(3): 242-246.
Abstract:
In the regional stratigraphic classification and correlation, the Lower Tertiary strata are absent in Guyang basin, Inner Mongolia. A suite of patchy-colour detrital rock system is identified in the Early Cretaceous Lisangou Formation determined by our predecessors. The present research into the stratigraphic features, sedimentary sequence, paleontologic assemblage, diagenesis and tectonic pattern of the said strata shows that this suite of strata overlying unconformably the Early Cretaceous Lisangou Formation is characterized by loose cementation, poor diagenesis, simple tectonic style (dominated by the fault-block movement) and Angiosperm-herb pollen assemblage. Furthermore, the distinctive differences are present between this suite of strata and the Early Cretaceous Lisangou Formation in terms of biological assembly, diagenesis and tectonic pattern. The analysis of the biologic assemblage of this suite of strata indicate the formation age of the strata at the Early Tertiary.
In the regional stratigraphic classification and correlation, the Lower Tertiary strata are absent in Guyang basin, Inner Mongolia. A suite of patchy-colour detrital rock system is identified in the Early Cretaceous Lisangou Formation determined by our predecessors. The present research into the stratigraphic features, sedimentary sequence, paleontologic assemblage, diagenesis and tectonic pattern of the said strata shows that this suite of strata overlying unconformably the Early Cretaceous Lisangou Formation is characterized by loose cementation, poor diagenesis, simple tectonic style (dominated by the fault-block movement) and Angiosperm-herb pollen assemblage. Furthermore, the distinctive differences are present between this suite of strata and the Early Cretaceous Lisangou Formation in terms of biological assembly, diagenesis and tectonic pattern. The analysis of the biologic assemblage of this suite of strata indicate the formation age of the strata at the Early Tertiary.
2000, 25(3): 247-252.
Abstract:
The regional geological mapping is used to analyze the fold structure of the Zhaertaishan Group in Guyang County, Inner Mongolia. In the geological evolution of the fold structure, this suite of strata experienced three stages of fold deformation: the intraformational fold in the early stage, the homoclinal reverse fold in the major stage, and the superimposed fold in the late stage. The intraformational fold that occurred in the Meso-Proterozoic and developed in the Agulugou Formation, was caused by the shear-slip between formations. The homoclinal reverse fold occurred in the Meso-Proterozoic. The superimposed fold in the late stage occurred in the Early Paleozoic. The latter two folds were both derived from the longitudinal folding mechanism. The restructuring of the fold in the major stage by the fold in the late stage resulted in the formation of a relatively complex superimposed structural network.
The regional geological mapping is used to analyze the fold structure of the Zhaertaishan Group in Guyang County, Inner Mongolia. In the geological evolution of the fold structure, this suite of strata experienced three stages of fold deformation: the intraformational fold in the early stage, the homoclinal reverse fold in the major stage, and the superimposed fold in the late stage. The intraformational fold that occurred in the Meso-Proterozoic and developed in the Agulugou Formation, was caused by the shear-slip between formations. The homoclinal reverse fold occurred in the Meso-Proterozoic. The superimposed fold in the late stage occurred in the Early Paleozoic. The latter two folds were both derived from the longitudinal folding mechanism. The restructuring of the fold in the major stage by the fold in the late stage resulted in the formation of a relatively complex superimposed structural network.
2000, 25(3): 253-259.
Abstract:
The petroleum migration is not only an important theoretical problem but also a puzzle in petroleum geology. In this paper, the organic geochemical analytical results of the crude oil and source rocks, especially the biomarker compositions, are used to classify the petroleum types for the correlation between the petroleum sources, with some examples of oil fields within the Zhanhua sag, northeast of Jiyang depression. In this case, the features can be summarized of the multi-phase petroleum migration and accumulation in the rift-subsidence basin. The present research results support the correlation between the formation of the -phase petroleum migration and accumulation. The Kenxi oilfield in the marginal fault zone is a product of the alternation of petroleum migration directions: the lateral migration through the carrier beds and the vertical migration through the faults. The formation of the Gudao-type Guqianshan oilfield is related to the third petroleum migration from the lower Tertiary pool. The lateral migration and filling within the rift-subsidence basin often result in the formation single-source petroleum accumulation, but the vertical filling at the fault zone often results in the formation of the mixed-source petroleum accumulation. Therefore, the multi-phase petroleum migration is related to the duration and episodes of the fracturing activity within the basin.
The petroleum migration is not only an important theoretical problem but also a puzzle in petroleum geology. In this paper, the organic geochemical analytical results of the crude oil and source rocks, especially the biomarker compositions, are used to classify the petroleum types for the correlation between the petroleum sources, with some examples of oil fields within the Zhanhua sag, northeast of Jiyang depression. In this case, the features can be summarized of the multi-phase petroleum migration and accumulation in the rift-subsidence basin. The present research results support the correlation between the formation of the -phase petroleum migration and accumulation. The Kenxi oilfield in the marginal fault zone is a product of the alternation of petroleum migration directions: the lateral migration through the carrier beds and the vertical migration through the faults. The formation of the Gudao-type Guqianshan oilfield is related to the third petroleum migration from the lower Tertiary pool. The lateral migration and filling within the rift-subsidence basin often result in the formation single-source petroleum accumulation, but the vertical filling at the fault zone often results in the formation of the mixed-source petroleum accumulation. Therefore, the multi-phase petroleum migration is related to the duration and episodes of the fracturing activity within the basin.
2000, 25(3): 260-266.
Abstract:
The structural slope-break zone, resulting in the abrupt change of the depositional slope, is initiated by the long-term activity of syndepositional structure. The researches into the Bohaiwan basin indicate that the structural slope-break zone in the fault subsidence lacustrine basin constrained the change in the accommodation space of the basins, controlling the development of the depositional sequence and the distribution of the depositional system tracts and the sand bodies. The half-graben basin may accommodate the following four kinds of structual slope-break zones: uplift-gentle-slope margins, gentle slope-depression margins, steep-slope-depression margins, and uplift-steep-slope margins. Furthermore, several syndepositional structural (fault) slope-break patterns are identified such as "comb-like structure" and "broom-like structure". These structures controlled the distribution patterns of the specific depositional systems tracts and the sand bodies in the basin. The structural slope-break zone is favorable for the formation of petroleum accumulation. The structual slope-break zone at the depression margin such as the "comb-like structure" has proved important for the prediction and exploration of the deep-seated subtle traps in the basin.
The structural slope-break zone, resulting in the abrupt change of the depositional slope, is initiated by the long-term activity of syndepositional structure. The researches into the Bohaiwan basin indicate that the structural slope-break zone in the fault subsidence lacustrine basin constrained the change in the accommodation space of the basins, controlling the development of the depositional sequence and the distribution of the depositional system tracts and the sand bodies. The half-graben basin may accommodate the following four kinds of structual slope-break zones: uplift-gentle-slope margins, gentle slope-depression margins, steep-slope-depression margins, and uplift-steep-slope margins. Furthermore, several syndepositional structural (fault) slope-break patterns are identified such as "comb-like structure" and "broom-like structure". These structures controlled the distribution patterns of the specific depositional systems tracts and the sand bodies in the basin. The structural slope-break zone is favorable for the formation of petroleum accumulation. The structual slope-break zone at the depression margin such as the "comb-like structure" has proved important for the prediction and exploration of the deep-seated subtle traps in the basin.
2000, 25(3): 273-277.
Abstract:
The contrast in geological conditions for the coalbed methane between North China and United States indicates that the telemagmatic thermal metamorphism is favorable for the increase of the coalbed methane volume and permeability characteristic of coal metamorphism in North China. Additionally, the mechanism of the telemagmatic thermal metamorphism is discussed in this paper. The majority of coals in North China were ranked in the low level before the intrusion of Yanshanian magma. Therefore, at the high temperature caused by the rapid increase of the temperature, the coalbed methane occurred the second time. That is to say the coalbed was of great potential to the "superimposed hydrocarbon generation" or "superimposed coalbed-methane generation". The porosity and fissure system turned more developed. Moreover, the late generation of the coalbed methane derived from the telemagmatic thermal metamorphism favored the reservation of the coalbed methane. The coal-rank zonings superimposed by the telemagmatic thermal metamorphism, including high-rank and middle-rank coals, increase distinctively the methane content and the permeability. Therefore, special attention should be paid to the location of the coalbed-methane prospecting target in the telemagmatic thermal metamorphic coals.
The contrast in geological conditions for the coalbed methane between North China and United States indicates that the telemagmatic thermal metamorphism is favorable for the increase of the coalbed methane volume and permeability characteristic of coal metamorphism in North China. Additionally, the mechanism of the telemagmatic thermal metamorphism is discussed in this paper. The majority of coals in North China were ranked in the low level before the intrusion of Yanshanian magma. Therefore, at the high temperature caused by the rapid increase of the temperature, the coalbed methane occurred the second time. That is to say the coalbed was of great potential to the "superimposed hydrocarbon generation" or "superimposed coalbed-methane generation". The porosity and fissure system turned more developed. Moreover, the late generation of the coalbed methane derived from the telemagmatic thermal metamorphism favored the reservation of the coalbed methane. The coal-rank zonings superimposed by the telemagmatic thermal metamorphism, including high-rank and middle-rank coals, increase distinctively the methane content and the permeability. Therefore, special attention should be paid to the location of the coalbed-methane prospecting target in the telemagmatic thermal metamorphic coals.
2000, 25(3): 278-282.
Abstract:
In this study, the coal sample series are analyzed with both natural and artificial maturity series. Then the pyrolytic simulation method is employed to address the lagging and reaction kinetic mechanism of the hydrocarbon regeneration from the organic matters in coals. This analysis indicates that the initial maturity of the hydrocarbon regeneration increased and the peak maturity of the hydrocarbon regeneration shifted backward in a regular pattern with the "deadline" of this generation standing at about 4.0% (Ro). The difference between the peak and initial maturities of the hydrocarbon regeneration grows in a parabola pattern with the increasing initial maturity. In addition, the absolute and the relative laggings of the hydrocarbon regeneration evolve stage by stage. Therefore, the lagging range of the hydrocarbon regeneration might be forecasted. The stage-like variation of the half-peak width curve of the hydrocarbon regeneration with the initial maturity inferred the location of the initial maturity of the hydrocarbon regeneration in the hydrocarbon source rocks, near the hydrocarbon generation peak, which may yield a relatively great mount of hydrocarbon. At the same time, the mean activation energy of the coal samples with original maturity has evolved through four stages, highly matching the pyrolytic hydrocarbon generation and the stage evolution features of the lagging of the hydrocarbon regeneration. This perfect matching indicates the strict constraint of the geochemical mechanism of the reaction kinetics on the hydrocarbon regeneration.
In this study, the coal sample series are analyzed with both natural and artificial maturity series. Then the pyrolytic simulation method is employed to address the lagging and reaction kinetic mechanism of the hydrocarbon regeneration from the organic matters in coals. This analysis indicates that the initial maturity of the hydrocarbon regeneration increased and the peak maturity of the hydrocarbon regeneration shifted backward in a regular pattern with the "deadline" of this generation standing at about 4.0% (Ro). The difference between the peak and initial maturities of the hydrocarbon regeneration grows in a parabola pattern with the increasing initial maturity. In addition, the absolute and the relative laggings of the hydrocarbon regeneration evolve stage by stage. Therefore, the lagging range of the hydrocarbon regeneration might be forecasted. The stage-like variation of the half-peak width curve of the hydrocarbon regeneration with the initial maturity inferred the location of the initial maturity of the hydrocarbon regeneration in the hydrocarbon source rocks, near the hydrocarbon generation peak, which may yield a relatively great mount of hydrocarbon. At the same time, the mean activation energy of the coal samples with original maturity has evolved through four stages, highly matching the pyrolytic hydrocarbon generation and the stage evolution features of the lagging of the hydrocarbon regeneration. This perfect matching indicates the strict constraint of the geochemical mechanism of the reaction kinetics on the hydrocarbon regeneration.
2000, 25(3): 283-289.
Abstract:
An asymmetric and conjugate low-angle shear fracture system is identified in the multi-phase complex fracture systems within the rock mass of the Three Gorges dam region, with the help of the rock frictional rheology theory and the structural analytical method. The geometry and kinetic indicators show that this conjugate shear fracture system affected by the sliding-resistance stability in the deep and shallow layers of the dam occurred at a relatively early age, and then was sheared and modified by the fracture systems in the later period, constrained by the heterogeneity of the rock mass. In this sense, this conjugate shear fracture system is a product of the asymmetrical coaxial deformation restrained by the high fluid pressure.
An asymmetric and conjugate low-angle shear fracture system is identified in the multi-phase complex fracture systems within the rock mass of the Three Gorges dam region, with the help of the rock frictional rheology theory and the structural analytical method. The geometry and kinetic indicators show that this conjugate shear fracture system affected by the sliding-resistance stability in the deep and shallow layers of the dam occurred at a relatively early age, and then was sheared and modified by the fracture systems in the later period, constrained by the heterogeneity of the rock mass. In this sense, this conjugate shear fracture system is a product of the asymmetrical coaxial deformation restrained by the high fluid pressure.
ADVANCES IN LOWER AND MIDDLE TRIASSIC STRATIGRAPHIC RESEARCH IN EAST OF EASTERN KUNLUN OROGENIC BELT
2000, 25(3): 290-294.
Abstract:
The Lower and Middle Triassic strata, east of Eastern Kunlun orogenic belt, contains the Lower Triassic Hongshuichuan Group and the Middle Triassic Naocangjiangou Formation. The studies of body and trace fossils, as well as those of the regional lithology correlation, show that the Lower Triassic Hongshuichuan Group included in the Lower Triassic Indian stage and Olenekian stage, are divided into three lithological units: the sandstone and conglomerate unit at the bottom, the limestone with sandstone unit in the middle, and the sandstone and slate unit at the top. The Naocangjiangou Formation ranging from the early Middle Traissic to Middle Anisian includes two members: the sandstone and conglomerate member at the bottom and the sandstone and slate member at the top. The analysis of constant elements in the sandstone indicates that the majority of sandstones are composed of greywacke, belonging to the turbidite in a flysch basin. The eigenvalues of the rare-earth elements in the sandstone are close to the parameters of the rare-earth elements located in the active continental margin and in the continental arc.
The Lower and Middle Triassic strata, east of Eastern Kunlun orogenic belt, contains the Lower Triassic Hongshuichuan Group and the Middle Triassic Naocangjiangou Formation. The studies of body and trace fossils, as well as those of the regional lithology correlation, show that the Lower Triassic Hongshuichuan Group included in the Lower Triassic Indian stage and Olenekian stage, are divided into three lithological units: the sandstone and conglomerate unit at the bottom, the limestone with sandstone unit in the middle, and the sandstone and slate unit at the top. The Naocangjiangou Formation ranging from the early Middle Traissic to Middle Anisian includes two members: the sandstone and conglomerate member at the bottom and the sandstone and slate member at the top. The analysis of constant elements in the sandstone indicates that the majority of sandstones are composed of greywacke, belonging to the turbidite in a flysch basin. The eigenvalues of the rare-earth elements in the sandstone are close to the parameters of the rare-earth elements located in the active continental margin and in the continental arc.
2000, 25(3): 295-301.
Abstract:
The detailed investigation into the amphibole two-pyroxene granulite in the north of Dabie metamorphic terrain in terms of petrography, mineral chemistry, petrochemistry, and estimated p-t conditions for metamorphism indicates that this rock is a product of the garnet pyroxenite that experienced the granulite-facies retrograde metamorphism during its uplift. The peak metamorphism occurred at least in the high-pressure eclogite facies at a lower temperature gradient. The retrograde metamorphism p-t path of the garnet pyroxenite was characterized by the near isothermal decompression in the early stage, the near isobaric temperature rise in the middle stage and the temperature fall and decompression in the late stage. These features suggest that the p-t conditions of peak metamorphism in the northern Dabie terrain are higher than that of granulite facies.
The detailed investigation into the amphibole two-pyroxene granulite in the north of Dabie metamorphic terrain in terms of petrography, mineral chemistry, petrochemistry, and estimated p-t conditions for metamorphism indicates that this rock is a product of the garnet pyroxenite that experienced the granulite-facies retrograde metamorphism during its uplift. The peak metamorphism occurred at least in the high-pressure eclogite facies at a lower temperature gradient. The retrograde metamorphism p-t path of the garnet pyroxenite was characterized by the near isothermal decompression in the early stage, the near isobaric temperature rise in the middle stage and the temperature fall and decompression in the late stage. These features suggest that the p-t conditions of peak metamorphism in the northern Dabie terrain are higher than that of granulite facies.
2000, 25(3): 302-305.
Abstract:
The opal crystalline state and colour patch have always been a hot issue in the gemmological community. However, very few literatures are focused on origins of the "silky" and "honeycomb-like cellular" colour patches, an important feature for the differentiation between natural and synthetic opals. For this reason, the authors tested and analyzed many opal samples using conventional gemmological test, SEM, and XRD. The research shows that the opal is in a continuous gradual changing state ranging from the noncrystalline to the crystallite to the sub-microscopic cryptocrystalline and finally to the cryptocrystalline. In addition, no distinct boundary is present between each two states. Furthermore, the opal may exist as an aggregate in all these different states. In this paper, the authors propose a gemological criterion to differentiate between the opal and the chalcedony, and also show different mechanisms for the formation of these two different colour patches. The "silky" colour patch occurs when the light is dispersed from the microscopic fissures inside the natural opal, but the "honeycomb-like cellular" colour patch is determined by the distribution of the SiO2 spheres and the light transmittance characteristic of the spheres themselves within the synthetic opal. The understanding of the origins of these two colour patches has provided us with the theoretical basis for the differentiation between natural and synthetic opals.
The opal crystalline state and colour patch have always been a hot issue in the gemmological community. However, very few literatures are focused on origins of the "silky" and "honeycomb-like cellular" colour patches, an important feature for the differentiation between natural and synthetic opals. For this reason, the authors tested and analyzed many opal samples using conventional gemmological test, SEM, and XRD. The research shows that the opal is in a continuous gradual changing state ranging from the noncrystalline to the crystallite to the sub-microscopic cryptocrystalline and finally to the cryptocrystalline. In addition, no distinct boundary is present between each two states. Furthermore, the opal may exist as an aggregate in all these different states. In this paper, the authors propose a gemological criterion to differentiate between the opal and the chalcedony, and also show different mechanisms for the formation of these two different colour patches. The "silky" colour patch occurs when the light is dispersed from the microscopic fissures inside the natural opal, but the "honeycomb-like cellular" colour patch is determined by the distribution of the SiO2 spheres and the light transmittance characteristic of the spheres themselves within the synthetic opal. The understanding of the origins of these two colour patches has provided us with the theoretical basis for the differentiation between natural and synthetic opals.
2000, 25(3): 306-310.
Abstract:
The intensity of 3-D vector cut is an important indicator for the quality test of a 3-D digital basin model established. After the reiteration of vector cut principle of the B-Rep model-based 3-D digital basin, this paper deals with the technical approaches and methods for the actualization of the vector shearing function on a microcomputer. On the basis of vector shearing of four graphical primitives: line, polygon, surface and text, the author established a relatively perfect vector cut model for 3-D digital tectonic-stratigraphic basin, and, furthermore, wrote the corresponding software. The vector cut analysis of the Zhusan depression by means of this technical approach and software system has brought about an expected result.
The intensity of 3-D vector cut is an important indicator for the quality test of a 3-D digital basin model established. After the reiteration of vector cut principle of the B-Rep model-based 3-D digital basin, this paper deals with the technical approaches and methods for the actualization of the vector shearing function on a microcomputer. On the basis of vector shearing of four graphical primitives: line, polygon, surface and text, the author established a relatively perfect vector cut model for 3-D digital tectonic-stratigraphic basin, and, furthermore, wrote the corresponding software. The vector cut analysis of the Zhusan depression by means of this technical approach and software system has brought about an expected result.
2000, 25(3): 311-318.
Abstract:
Multifractal model is used to measure the multifractal distribution by means of not only the conventional low-order moment statistics but also the high-order moment statistics. Therefore, this model can be used to measure the statistical properties of the anomalous values as well as the background geochemical values. The background geochemical values usually follow normal or lognormal distributions, but the anomalous values may follow fractal (Preato) distributions. This paper introduces some recent developments of multifractal modeling and their applications to geochemistry, in particular to the spatial distribution and concentration pattern of trace elements. The results show that the ordinary statistical methods are effective only for the understanding of local properties of the values surrounding the multifractal mean value. In order to characterize effectively the distribution and concentration pattern of the anomalous values, this paper proposes the high-order moment statistical method and multifractal method. Furthermore, two methods have been given in this paper for the analyses of geochemical elements and anomalous values: concentration-area (C—A) fractal method and high-order correlation coefficient. The former method is used for separating anomalies from their background values and the latter is for enhancing the correlation coefficient between anomalous values of multiple elements. A case study is used to illustrate the application of these methods to the detection of Au/Cu-associated alteration zones in the Mitchell-Sulphurests mineral district, northwest of B.C. Province, Canada.
Multifractal model is used to measure the multifractal distribution by means of not only the conventional low-order moment statistics but also the high-order moment statistics. Therefore, this model can be used to measure the statistical properties of the anomalous values as well as the background geochemical values. The background geochemical values usually follow normal or lognormal distributions, but the anomalous values may follow fractal (Preato) distributions. This paper introduces some recent developments of multifractal modeling and their applications to geochemistry, in particular to the spatial distribution and concentration pattern of trace elements. The results show that the ordinary statistical methods are effective only for the understanding of local properties of the values surrounding the multifractal mean value. In order to characterize effectively the distribution and concentration pattern of the anomalous values, this paper proposes the high-order moment statistical method and multifractal method. Furthermore, two methods have been given in this paper for the analyses of geochemical elements and anomalous values: concentration-area (C—A) fractal method and high-order correlation coefficient. The former method is used for separating anomalies from their background values and the latter is for enhancing the correlation coefficient between anomalous values of multiple elements. A case study is used to illustrate the application of these methods to the detection of Au/Cu-associated alteration zones in the Mitchell-Sulphurests mineral district, northwest of B.C. Province, Canada.
2000, 25(3): 319-323.
Abstract:
The fracture process of transparent samples are used in this paper to simulate that of a homogeneous rock mass. In order to discover relationships between the micro-fracture nucleation and its surrounding stress field, a real-time holographic optical setup is used to record the distribution and variations of the samples' stress fields and the transient wave-form automatic recorder is used to record the location and intensity of the micro-fractures. The initial research has brought about some phenomena worthy of notice. This method has provided us with a new approach to make a seismic experimental research.
The fracture process of transparent samples are used in this paper to simulate that of a homogeneous rock mass. In order to discover relationships between the micro-fracture nucleation and its surrounding stress field, a real-time holographic optical setup is used to record the distribution and variations of the samples' stress fields and the transient wave-form automatic recorder is used to record the location and intensity of the micro-fractures. The initial research has brought about some phenomena worthy of notice. This method has provided us with a new approach to make a seismic experimental research.
2000, 25(3): 324-328.
Abstract:
In this paper, two technical methods: the diamond coating and the addition of rare earth elements to matrix materials, are proposed, in line with the results derived from the experimental research, to improve the thermal stability of diamonds, the cohesion of matrix materials to the diamonds and their corresponding performance. These two technical methods can serve as favorable conditions for the substitution of Fe for Co in the matrix material.
In this paper, two technical methods: the diamond coating and the addition of rare earth elements to matrix materials, are proposed, in line with the results derived from the experimental research, to improve the thermal stability of diamonds, the cohesion of matrix materials to the diamonds and their corresponding performance. These two technical methods can serve as favorable conditions for the substitution of Fe for Co in the matrix material.
2000, 25(3): 329-332.
Abstract:
This paper presents a new type of composite button composed of diamond and cubic boron nitride-enhanced tungsten carbide. The working properties such as hardness, bending strength, and abrasion ratio of this type of composite button increases by a large margin because of the integration of the boron-sintering promotion and enhancement, the Ni-P activation sintering, and the addition of cubic boron nitride. In addition, a transitional zone between diamond particles and matrix alloy can effectively prevent the carbon atoms of the diamond surface from diffusion, a key element to protect diamond from deformation and damage at a high temperature. Furthermore, this transitional zone increases greatly the bonding strength between diamond and matrix alloy.
This paper presents a new type of composite button composed of diamond and cubic boron nitride-enhanced tungsten carbide. The working properties such as hardness, bending strength, and abrasion ratio of this type of composite button increases by a large margin because of the integration of the boron-sintering promotion and enhancement, the Ni-P activation sintering, and the addition of cubic boron nitride. In addition, a transitional zone between diamond particles and matrix alloy can effectively prevent the carbon atoms of the diamond surface from diffusion, a key element to protect diamond from deformation and damage at a high temperature. Furthermore, this transitional zone increases greatly the bonding strength between diamond and matrix alloy.
