2000 Vol. 25, No. 4
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2000, 25(4): 333-339.
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Abstract:
Mineralization system, a natural system with ore forming function often within a certain geological time space zone, includes the geological factors controlling the ore formation and preservation, the ore forming processes and their products, namely the ore deposit series and anomaly series. Based on the combination of the principal trend of metallogenic research with the author's personal study (both practice experience and academic thinking) of mineral deposits, the author considers that the study of the metallogenic system will be an important research field in metallogeny for a certain long period. From the system and history points of view, the author suggests that the metallogenic system and its evolution is one of keys to the metallogenic research. The analysis of the geological and metallogenic characteristics in China shows that the study of the evolution of the metallogenic system is of great importance to the understanding of the metallogenic patterns in China. Furthermore, a metallogenic system model is constructed, and the universal significance of boundary ore formation, transformational ore formation and coupling ore formation is stressed in this paper. Finally, the author proposes that the ore forming products include ore deposit series and anomaly series, and that attention should be paid to the study of the post mineralization changes and preservation. All the mentioned above topics are of great significance both in theory and practice.
Mineralization system, a natural system with ore forming function often within a certain geological time space zone, includes the geological factors controlling the ore formation and preservation, the ore forming processes and their products, namely the ore deposit series and anomaly series. Based on the combination of the principal trend of metallogenic research with the author's personal study (both practice experience and academic thinking) of mineral deposits, the author considers that the study of the metallogenic system will be an important research field in metallogeny for a certain long period. From the system and history points of view, the author suggests that the metallogenic system and its evolution is one of keys to the metallogenic research. The analysis of the geological and metallogenic characteristics in China shows that the study of the evolution of the metallogenic system is of great importance to the understanding of the metallogenic patterns in China. Furthermore, a metallogenic system model is constructed, and the universal significance of boundary ore formation, transformational ore formation and coupling ore formation is stressed in this paper. Finally, the author proposes that the ore forming products include ore deposit series and anomaly series, and that attention should be paid to the study of the post mineralization changes and preservation. All the mentioned above topics are of great significance both in theory and practice.
2000, 25(4): 340-345.
Abstract:
The ore formation is a result of complex geological processes. The majority of ore deposits is subject to changes in various forms and degrees after their formation. The ore deposit geology is to study the ore forming process (genesis) as well as the post ore changes and modifications, so as to increase the probability of ore prediction. The main post ore changes are classified as following six aspects: (1) the controlling parameters, (2) the changing and modification process, (3) the product of post ore modification, (4) the different modification track of various ore deposit types, (5) the ore deposit modifications in different geological environments and periods, and (6) the conditions for ore deposit preservation. The basic methods for post ore changes include the geological mapping, geochemical analysis and simulation experiments. In order to establish the post ore change models of certain ore deposit types, we should not only study the single ore deposit, but also the ore deposit series in a certain metallogenic belt. The research into the post ore changes is not only favorable for the forecasting and exploration of mineral resources, but also beneficial for the improvement of the ecological environments of mining area.
The ore formation is a result of complex geological processes. The majority of ore deposits is subject to changes in various forms and degrees after their formation. The ore deposit geology is to study the ore forming process (genesis) as well as the post ore changes and modifications, so as to increase the probability of ore prediction. The main post ore changes are classified as following six aspects: (1) the controlling parameters, (2) the changing and modification process, (3) the product of post ore modification, (4) the different modification track of various ore deposit types, (5) the ore deposit modifications in different geological environments and periods, and (6) the conditions for ore deposit preservation. The basic methods for post ore changes include the geological mapping, geochemical analysis and simulation experiments. In order to establish the post ore change models of certain ore deposit types, we should not only study the single ore deposit, but also the ore deposit series in a certain metallogenic belt. The research into the post ore changes is not only favorable for the forecasting and exploration of mineral resources, but also beneficial for the improvement of the ecological environments of mining area.
2000, 25(4): 346-351.
Abstract:
In the Paleoproterozoic Lieryu Formation and Dashiqiao Formation, eastern Liaoning Province, China, are distributed the magnesium rich carbonate rock formations, where occur large to super large sized deposits of borax, magnesite, talc, and serpentine. The formation of these magnesian non metallic deposits related to the evaporites of the Paleoproterozoic experienced the regional metamorphism and the hydrothermal metasomatism during the Lüliang orogeny, and also the mineralization process of tectono magmatism during the Indosinian Yanshanian. In particular, the magnesian carbonate rock formations, minerogenetic structures and ore forming fluids played a key role in the formation of the magnesian non metallic deposits. Therefore, it can be concluded that these mineral deposits are end products of the integration of the coupling of the Paleoproterozoic ore source field, fluid field, thermal field (energy field) and stress field on certain time space conditions with the superimposed reformation of tectono magmatism in the later stage.
In the Paleoproterozoic Lieryu Formation and Dashiqiao Formation, eastern Liaoning Province, China, are distributed the magnesium rich carbonate rock formations, where occur large to super large sized deposits of borax, magnesite, talc, and serpentine. The formation of these magnesian non metallic deposits related to the evaporites of the Paleoproterozoic experienced the regional metamorphism and the hydrothermal metasomatism during the Lüliang orogeny, and also the mineralization process of tectono magmatism during the Indosinian Yanshanian. In particular, the magnesian carbonate rock formations, minerogenetic structures and ore forming fluids played a key role in the formation of the magnesian non metallic deposits. Therefore, it can be concluded that these mineral deposits are end products of the integration of the coupling of the Paleoproterozoic ore source field, fluid field, thermal field (energy field) and stress field on certain time space conditions with the superimposed reformation of tectono magmatism in the later stage.
2000, 25(4): 352-355.
Abstract:
In Dayaoshan Xidamingshan area, both the main gold silver mining region and the important mineral prospecting region in Guangxi, the gold silver deposits are mainly situated in the Cambrian strata. The Au-Ag mineralization was closely related to the tectonic activity and magmatism in the Caledonian and Yanshanian movements, resulting in the Au-Ag-Cu metallogenic series related to the syntectic/compressive granite. In this way, the magmatic and hydrothermal ore forming system was established on the extrusive structure in this area.
In Dayaoshan Xidamingshan area, both the main gold silver mining region and the important mineral prospecting region in Guangxi, the gold silver deposits are mainly situated in the Cambrian strata. The Au-Ag mineralization was closely related to the tectonic activity and magmatism in the Caledonian and Yanshanian movements, resulting in the Au-Ag-Cu metallogenic series related to the syntectic/compressive granite. In this way, the magmatic and hydrothermal ore forming system was established on the extrusive structure in this area.
2000, 25(4): 356-361.
Abstract:
In the Xiuyan gold deposit located at the contact zone between the Indo Chinese granitic batholith and the Lower Proterozoic metamorphic xenolith in Liaohe Group, the mineralization types are composed mainly of the quartz vein type and minorly of the altered rock type. This study reveals that a granitic magma system closely associated with the mineralization in terms of space, time and materials, accounts for the gold mineralization. The analysis of the fluid inclusion indicates that there are several sorts of inclusions in vein quartz, that the ratios of gas to (liquid + gas) ranges very widely, that the homogenization temperature (th) is high with the highest temperature rising to 500 ℃, that the th distribution reflects the multi peak model, and that the inclusions rich in CO 2 and organism are easily discovered, typical magma source and mantle source. The mineralization types are controlled both by the tectonic stress field and by the fracture mechanic property.
In the Xiuyan gold deposit located at the contact zone between the Indo Chinese granitic batholith and the Lower Proterozoic metamorphic xenolith in Liaohe Group, the mineralization types are composed mainly of the quartz vein type and minorly of the altered rock type. This study reveals that a granitic magma system closely associated with the mineralization in terms of space, time and materials, accounts for the gold mineralization. The analysis of the fluid inclusion indicates that there are several sorts of inclusions in vein quartz, that the ratios of gas to (liquid + gas) ranges very widely, that the homogenization temperature (th) is high with the highest temperature rising to 500 ℃, that the th distribution reflects the multi peak model, and that the inclusions rich in CO 2 and organism are easily discovered, typical magma source and mantle source. The mineralization types are controlled both by the tectonic stress field and by the fracture mechanic property.
2000, 25(4): 362-368.
Abstract:
This paper addresses the geological evolution and tectonic zonation of the northern margin of North China platform where are successively distributed from the south to the north the Wulashan Seertengshan Daqingshan intracontinental upwarping zone, the Dongshengmiao Chaertaishan intracontinental rift, the Langshan Shihahe pericontinental upwarping zone, the Huogeqi Bayan Obo pericontinental rift, the Bainaimiao Baiyindusi rift and upwarping zone, the Wenduermiao Ailigemiao rift. This paper analyzes the pericontinental basement formation and rift sedimentary formation, classifies the rift sedimentation during the splitting and subsiding periods. In addition, this paper deals with the metallogenic system. The identity and the successiveness of the metallogenic material sources are used for the classification of the metallogenic system as four subsystems as shown below: (1) The metallogenic system of metamorphic gold deposit established on the basis of material sources of greenstone formation and composed of various ore deposit type assemblages. This system occurs mainly in the metamorphic area of the upwarping zone in the palaeo continents. (2) The SEDEX metallogenic system in the marine volcanic spilite. This system, mainly composed of Cu Pb Zn polymetallic deposits and mainly occurring in the volcanic rock formation shaped during the rift splitting period, is related to the hydrothermal erupting in the same period of magmas produced in the volcanic activity. (3) The metallogenic system of the spout telescoped deposit in the alkaline rock and carbonatite. This system occurred early in the alkaline volcanic carbonatite of the Bayan Obo rift, with the spout sediments of high temperature silica potassium hydrothermal solution, resulting in the rare element REE iron telescoped deposits. The main ore deposit and the east ore deposit underwent strong weathering and denudation, and alluvial enrichment occured since Cenozoic era.
This paper addresses the geological evolution and tectonic zonation of the northern margin of North China platform where are successively distributed from the south to the north the Wulashan Seertengshan Daqingshan intracontinental upwarping zone, the Dongshengmiao Chaertaishan intracontinental rift, the Langshan Shihahe pericontinental upwarping zone, the Huogeqi Bayan Obo pericontinental rift, the Bainaimiao Baiyindusi rift and upwarping zone, the Wenduermiao Ailigemiao rift. This paper analyzes the pericontinental basement formation and rift sedimentary formation, classifies the rift sedimentation during the splitting and subsiding periods. In addition, this paper deals with the metallogenic system. The identity and the successiveness of the metallogenic material sources are used for the classification of the metallogenic system as four subsystems as shown below: (1) The metallogenic system of metamorphic gold deposit established on the basis of material sources of greenstone formation and composed of various ore deposit type assemblages. This system occurs mainly in the metamorphic area of the upwarping zone in the palaeo continents. (2) The SEDEX metallogenic system in the marine volcanic spilite. This system, mainly composed of Cu Pb Zn polymetallic deposits and mainly occurring in the volcanic rock formation shaped during the rift splitting period, is related to the hydrothermal erupting in the same period of magmas produced in the volcanic activity. (3) The metallogenic system of the spout telescoped deposit in the alkaline rock and carbonatite. This system occurred early in the alkaline volcanic carbonatite of the Bayan Obo rift, with the spout sediments of high temperature silica potassium hydrothermal solution, resulting in the rare element REE iron telescoped deposits. The main ore deposit and the east ore deposit underwent strong weathering and denudation, and alluvial enrichment occured since Cenozoic era.
2000, 25(4): 369-374.
Abstract:
The highly strained structural belts in some units of palaeo plate tectonics, products of subduction and collision of various scale plates in East Junggar, controlled the distribution of the majority of the endogenetic gold deposits and occurrences, turning into the most important gold metallogenic system in East Junggar. The epicontinental volcanic magma arcs and residual sea basins that occurred at the stages of the oceanic crust subduction and oceanic basin closure, and the epicontinental volcaniclastic sedimentary facies, the carbonaceous sedimentary facies and the melange ophiolite blocks that occurred on the subduction zone are all included in the geological bodies with higher Au abundance, constituting the potential source beds (bodies) in the mineralization system in the highly strained structural belt. The thermal energy produced by the tectonic movement and derived from the deep structure is a kind of energy resource resulting both from the violent deformation and metamorphism and from the Au activation in this mineralization system. The ore forming fluids, driven by the stress difference within the tectonic zone, migrated from the violent compression zones to the extension zones with relative lower pressure and stress, resulting in the concentration of the gold deposits (occurrences) near the transitional zones between these two structural belts. The gold bodies and veins thus occurred in the secondary faults and fissures derived from these structural belts.
The highly strained structural belts in some units of palaeo plate tectonics, products of subduction and collision of various scale plates in East Junggar, controlled the distribution of the majority of the endogenetic gold deposits and occurrences, turning into the most important gold metallogenic system in East Junggar. The epicontinental volcanic magma arcs and residual sea basins that occurred at the stages of the oceanic crust subduction and oceanic basin closure, and the epicontinental volcaniclastic sedimentary facies, the carbonaceous sedimentary facies and the melange ophiolite blocks that occurred on the subduction zone are all included in the geological bodies with higher Au abundance, constituting the potential source beds (bodies) in the mineralization system in the highly strained structural belt. The thermal energy produced by the tectonic movement and derived from the deep structure is a kind of energy resource resulting both from the violent deformation and metamorphism and from the Au activation in this mineralization system. The ore forming fluids, driven by the stress difference within the tectonic zone, migrated from the violent compression zones to the extension zones with relative lower pressure and stress, resulting in the concentration of the gold deposits (occurrences) near the transitional zones between these two structural belts. The gold bodies and veins thus occurred in the secondary faults and fissures derived from these structural belts.
2000, 25(4): 375-379.
Abstract:
During the mineralization of the low temperature hydrothermal deposits, organisms and organic matters play an important metallogenic role deducted as two major categories: direct and indirect metallogenic roles. The direct metallogenic role of organisms and organic matters means the formation of source beds in the contemporaneous sedimentary stage, the formation of ore bearing fluids in the activation migration of mineralizing materials, and the formation of mineral deposits derived from the accumulation of mineralizing elements during the precipitation of mineralizing materials. The indirect metallogenic role refers to the fact that the maturation evolution of organic matters and relative organic products may reveal the mineralization process, reflecting the low temperature hydrothermal metallogenic mechanism and condition.
During the mineralization of the low temperature hydrothermal deposits, organisms and organic matters play an important metallogenic role deducted as two major categories: direct and indirect metallogenic roles. The direct metallogenic role of organisms and organic matters means the formation of source beds in the contemporaneous sedimentary stage, the formation of ore bearing fluids in the activation migration of mineralizing materials, and the formation of mineral deposits derived from the accumulation of mineralizing elements during the precipitation of mineralizing materials. The indirect metallogenic role refers to the fact that the maturation evolution of organic matters and relative organic products may reveal the mineralization process, reflecting the low temperature hydrothermal metallogenic mechanism and condition.
2000, 25(4): 380-383.
Abstract:
Up to now, the known diamond bearing rocks, pro alkaline and ultra mafic, include kimberlite, lamproite, eclogite, ophiolite suite, alkaline ultrabasic complex, alkaline ultrabasic lamprophyre, peridotite series (including harzburgite and dunite). However, the primary diamond deposits worthy of exploration in terms of economic value occur only in the kimberlite and lamproite. In addition, only a small amount of micro grain diamond occurs in other types of rocks. Although both kimberlite and lamproite originated from the deep mantle, relatively conspicuous differences arise in chemical compositions, rock forming minerals, tectonic settings, and isotope data, resulting in two metallogenic series of primary diamond deposits: kimberlite type and lamproite type primary diamond metallogenic series. The kimberlite type primary diamond metallogenic series is divided into three sub series of mineralization in terms of chemical compositions: rich Cr, Ti and Mg kimberlite type diamond metallogenic sub series, poor Cr, Ti and Mg kimberlite type diamond metallogenic sub series, and the kimberlite sub series with complex chemical compositions (of transitional type) between the first two sub series. However, the lamproite type primary diamond metallogenic series is classified in terms of major mineral components as olivine lamproite primary diamond metallogenic sub series, leucite lamproite primary diamond metallogenic sub series and the transitional subseries lying between the first two subseries. In the meantime, both the kimberlite type metallogenic series and the lamproite metallogenic series can be classified as three metallogenic subseries (from early to late) respectively in terms of their corresponding field geological occurrences: kimberlite/lamproite type volcanic sedimentary tuff primary diamond metallogenic sub series, kimberlite/lamproite type volcanic tuff and breccia primary diamond metallogenic sub series, and kimberlite/lamproite type volcanic subvolcanic intrusion facies primary diamond metallogenic sub series.
Up to now, the known diamond bearing rocks, pro alkaline and ultra mafic, include kimberlite, lamproite, eclogite, ophiolite suite, alkaline ultrabasic complex, alkaline ultrabasic lamprophyre, peridotite series (including harzburgite and dunite). However, the primary diamond deposits worthy of exploration in terms of economic value occur only in the kimberlite and lamproite. In addition, only a small amount of micro grain diamond occurs in other types of rocks. Although both kimberlite and lamproite originated from the deep mantle, relatively conspicuous differences arise in chemical compositions, rock forming minerals, tectonic settings, and isotope data, resulting in two metallogenic series of primary diamond deposits: kimberlite type and lamproite type primary diamond metallogenic series. The kimberlite type primary diamond metallogenic series is divided into three sub series of mineralization in terms of chemical compositions: rich Cr, Ti and Mg kimberlite type diamond metallogenic sub series, poor Cr, Ti and Mg kimberlite type diamond metallogenic sub series, and the kimberlite sub series with complex chemical compositions (of transitional type) between the first two sub series. However, the lamproite type primary diamond metallogenic series is classified in terms of major mineral components as olivine lamproite primary diamond metallogenic sub series, leucite lamproite primary diamond metallogenic sub series and the transitional subseries lying between the first two subseries. In the meantime, both the kimberlite type metallogenic series and the lamproite metallogenic series can be classified as three metallogenic subseries (from early to late) respectively in terms of their corresponding field geological occurrences: kimberlite/lamproite type volcanic sedimentary tuff primary diamond metallogenic sub series, kimberlite/lamproite type volcanic tuff and breccia primary diamond metallogenic sub series, and kimberlite/lamproite type volcanic subvolcanic intrusion facies primary diamond metallogenic sub series.
2000, 25(4): 384-389.
Abstract:
The comprehensive analysis of the factors controlling the formation of the gold deposits in Northwest Jiaodong Peninsula, and the comparison with the basic ore forming conditions of the concealed area in North Laizhou, Shandong Province, both pave the way for the construction of a possible ore forming model and clarify the key problems to gold exploration in the concealed area. In addition, the methods for the geophysical exploration, geochemical exploration and remote sensing are applied to the solutions to the aforementioned key problems. Finally, the combination of the theoretical ore forming analysis with the practical mineral exploration is briefly illustrated in this paper with an example of practical mineral exploration.
The comprehensive analysis of the factors controlling the formation of the gold deposits in Northwest Jiaodong Peninsula, and the comparison with the basic ore forming conditions of the concealed area in North Laizhou, Shandong Province, both pave the way for the construction of a possible ore forming model and clarify the key problems to gold exploration in the concealed area. In addition, the methods for the geophysical exploration, geochemical exploration and remote sensing are applied to the solutions to the aforementioned key problems. Finally, the combination of the theoretical ore forming analysis with the practical mineral exploration is briefly illustrated in this paper with an example of practical mineral exploration.
2000, 25(4): 390-396.
Abstract:
The systematic study of the depression belt in southwestern Fujian Province, one of the most significant tectonic and metallogenic unit in southeastern China, shows that the transformation from Tethyan Himalayan tectonic domain into circum Pacific tectonic domain in southeastern China from the Late Indo Chinese to the Early Yanshanian induced obvious changes in geophysics, tectono magmatic distribution, lithofacies and paleo geography, tectonic system and regional mineralization. Tectonic system analysis indicates that the tectonic regime in this area resulted from the amalgamation, transformation and superimposition between the two tectonic domains. The geodynamic mechanism of the transformation is mainly attributed to the latitudinal and longitudinal heterogeneities of lithosphere and to the interaction between crust and mantle. The analysis of the mineralization and that of the mineralization age show that the transformation of the tectonic regime was accompanied by one significant phase of the multi metal mineralization that should have occurred during the Late Indo Chinese to the Early Yanshanian in southeastern China.
The systematic study of the depression belt in southwestern Fujian Province, one of the most significant tectonic and metallogenic unit in southeastern China, shows that the transformation from Tethyan Himalayan tectonic domain into circum Pacific tectonic domain in southeastern China from the Late Indo Chinese to the Early Yanshanian induced obvious changes in geophysics, tectono magmatic distribution, lithofacies and paleo geography, tectonic system and regional mineralization. Tectonic system analysis indicates that the tectonic regime in this area resulted from the amalgamation, transformation and superimposition between the two tectonic domains. The geodynamic mechanism of the transformation is mainly attributed to the latitudinal and longitudinal heterogeneities of lithosphere and to the interaction between crust and mantle. The analysis of the mineralization and that of the mineralization age show that the transformation of the tectonic regime was accompanied by one significant phase of the multi metal mineralization that should have occurred during the Late Indo Chinese to the Early Yanshanian in southeastern China.
2000, 25(4): 397-403.
Abstract:
The comprehensive analysis of advances in the research into the ore forming dynamics concludes in this paper that the research into the ore forming dynamics of the tectonic regime transformation and multi layer circulation is on the cutting edge of the earth sciences in the 21st century. Then the paper presents the theme, key issues, methodology, and important significance of this research. In addition, this paper also proposes that the research into the ore forming dynamics of the tectonic regime transformation and the multi layer fluid circulation centers around the heterogeneities in the structural evolution, fluid activity, regional geochemistry and geophysics. The experiments on the deformation fluid high temperature and high pressure, the method for numerical simulation to reappear the ore forming process and mechanism, to analyze the ore forming dynamics of the tectonic regime transformation and multi layer fluid circulation, to reveal tempo spatial evolutionary patterns of the ore forming interfaces, and finally to construct the quantitative model of the exchange between material and energy feedback coupling mineralization in the mineralization system. This research, an important basis of the deeper understanding of the mineralization origin, and an effective approach to the scientific mineral prospecting, is of great significance to the research into the earth system science and continental dynamics.
The comprehensive analysis of advances in the research into the ore forming dynamics concludes in this paper that the research into the ore forming dynamics of the tectonic regime transformation and multi layer circulation is on the cutting edge of the earth sciences in the 21st century. Then the paper presents the theme, key issues, methodology, and important significance of this research. In addition, this paper also proposes that the research into the ore forming dynamics of the tectonic regime transformation and the multi layer fluid circulation centers around the heterogeneities in the structural evolution, fluid activity, regional geochemistry and geophysics. The experiments on the deformation fluid high temperature and high pressure, the method for numerical simulation to reappear the ore forming process and mechanism, to analyze the ore forming dynamics of the tectonic regime transformation and multi layer fluid circulation, to reveal tempo spatial evolutionary patterns of the ore forming interfaces, and finally to construct the quantitative model of the exchange between material and energy feedback coupling mineralization in the mineralization system. This research, an important basis of the deeper understanding of the mineralization origin, and an effective approach to the scientific mineral prospecting, is of great significance to the research into the earth system science and continental dynamics.
2000, 25(4): 404-409.
Abstract:
The Dongshengmiao Zn Pb Cu sulfide ore deposit hosted by the only ore bearing 2nd formation of the Mesoproterozoic Langshan Group and the Jiashengpan Zn Pb sulfide ore deposit hosted by the 2nd member of the Agulugou Formation of the Mesoproterozoic Zhaertai Group are both obviously strata bound and equivalent in their occurrence horizons. It is believed that the synchronous faulting occurred in the only ore bearing 2nd formation of Langshan Group and in the 2nd member of the Agulugou Formation, supported by the following evidences: (1) The sudden changes in lithofacies occurred in the ore bearing strata; (2) The thickness of the ore bearing strata suddenly varied along the strike and dipped with intraformational conglomerates, and olistolithes; (3) The Zn Pb Cu orebodies suddenly thickened and thinned or even wedged out; (4) In some Zn Pb, Zn Pb Cu and Zn Cu orebodies occurred the brecciated structure ores containing some blocks and fragments of dolomite marble, carbonaceous phyllite, quartzite, tuffs, granulites, metavolcanite, biotite schist and even Zn Pb or Py ores; (5) Some basic volcanic rocks and ruffs occurred in the linear distribution. The synchronous fault, favorable for the formation of the Dongshengmiao and Jiashengpan ore deposits, served as the path for both the volcanic eruption and the mineralized fluid exhaling into the ore bearing basins during the Mesoproterozoic. The variations in scale and history of the synchronous fault with different secondary depositional basins suggested the unevenness of the extensional processes resulting in the difference in the mineralization intensity and orebody distribution. The Dongshengmiao ore deposit had a longer history of synchronous fault than the Jiashengpan ore deposit. In this sense, the Dongshengmiao ore deposit is defined as the super large deposit, but the Jiashengpan ore deposit as the large one.
The Dongshengmiao Zn Pb Cu sulfide ore deposit hosted by the only ore bearing 2nd formation of the Mesoproterozoic Langshan Group and the Jiashengpan Zn Pb sulfide ore deposit hosted by the 2nd member of the Agulugou Formation of the Mesoproterozoic Zhaertai Group are both obviously strata bound and equivalent in their occurrence horizons. It is believed that the synchronous faulting occurred in the only ore bearing 2nd formation of Langshan Group and in the 2nd member of the Agulugou Formation, supported by the following evidences: (1) The sudden changes in lithofacies occurred in the ore bearing strata; (2) The thickness of the ore bearing strata suddenly varied along the strike and dipped with intraformational conglomerates, and olistolithes; (3) The Zn Pb Cu orebodies suddenly thickened and thinned or even wedged out; (4) In some Zn Pb, Zn Pb Cu and Zn Cu orebodies occurred the brecciated structure ores containing some blocks and fragments of dolomite marble, carbonaceous phyllite, quartzite, tuffs, granulites, metavolcanite, biotite schist and even Zn Pb or Py ores; (5) Some basic volcanic rocks and ruffs occurred in the linear distribution. The synchronous fault, favorable for the formation of the Dongshengmiao and Jiashengpan ore deposits, served as the path for both the volcanic eruption and the mineralized fluid exhaling into the ore bearing basins during the Mesoproterozoic. The variations in scale and history of the synchronous fault with different secondary depositional basins suggested the unevenness of the extensional processes resulting in the difference in the mineralization intensity and orebody distribution. The Dongshengmiao ore deposit had a longer history of synchronous fault than the Jiashengpan ore deposit. In this sense, the Dongshengmiao ore deposit is defined as the super large deposit, but the Jiashengpan ore deposit as the large one.
2000, 25(4): 410-415.
Abstract:
The analysis of orefield structure is not only an important method for the research into the genesis of mineral deposits, the mineralization patterns, and the prospecting forecasting, but also a relatively weak part of the research into the Suichang silver gold field. In this paper, by combining the system analysis of geology mechanics with the theories and methods for plate tectonics, the authors firstly present a brief description of the geological features of the orefield, and suggest two mineralization stages in the orefield: Luliang stage and Yanshan stage. Then, the authors present a specific description of the orebodies distribution patterns in the orefield, and classify the ore controlling tectonic systems as steeply tilted folding surface system, grating overprinting and remaking system and parallel fault damaged orebody system. Finally, by identifying the plate environments of the orefield in different mineralization stages, the authors determine the regional stress fields controlling the orefield and analyze the plate driven mechanism for ore controlling tectonic systems in different stages.
The analysis of orefield structure is not only an important method for the research into the genesis of mineral deposits, the mineralization patterns, and the prospecting forecasting, but also a relatively weak part of the research into the Suichang silver gold field. In this paper, by combining the system analysis of geology mechanics with the theories and methods for plate tectonics, the authors firstly present a brief description of the geological features of the orefield, and suggest two mineralization stages in the orefield: Luliang stage and Yanshan stage. Then, the authors present a specific description of the orebodies distribution patterns in the orefield, and classify the ore controlling tectonic systems as steeply tilted folding surface system, grating overprinting and remaking system and parallel fault damaged orebody system. Finally, by identifying the plate environments of the orefield in different mineralization stages, the authors determine the regional stress fields controlling the orefield and analyze the plate driven mechanism for ore controlling tectonic systems in different stages.
2000, 25(4): 416-420.
Abstract:
The statistical results of the multiple gradational faults and fractures in Jiaodong region demonstrate that the fault/fracture system conform to the fractal distribution within the scales from 10-6 to 104. The fractal dimensions of the fractures can be served as an index to distinguish between the altered structure belts and wall rocks. In this paper, the fractal distributions of fractures in Jiaojia gold deposit indicate that the deeper part of the orebody may be simpler and thicker than the shallow one. In this sense, greater prospecting potentials are present in the deep part of the gold deposit.
The statistical results of the multiple gradational faults and fractures in Jiaodong region demonstrate that the fault/fracture system conform to the fractal distribution within the scales from 10-6 to 104. The fractal dimensions of the fractures can be served as an index to distinguish between the altered structure belts and wall rocks. In this paper, the fractal distributions of fractures in Jiaojia gold deposit indicate that the deeper part of the orebody may be simpler and thicker than the shallow one. In this sense, greater prospecting potentials are present in the deep part of the gold deposit.
2000, 25(4): 421-427.
Abstract:
The information of geophysical field was, based on the results of 1∶1 000 00 aeromagnetic anomaly and 1∶2 000 00 Bouguer gravity anomaly in Jiaodong and its neighboring regions, Shandong, China, divided into two parts: deep-and shallow focus-field. The information of the two different fields was then combined with these of wave velocity anisotropy and deep-seated geology. The integrated result was adapted to the analysis of the three-dimension structure, the probe into deep seated mineralization and the dynamics of ore-forming system. This research indicated that the interaction and conversion of materials and energy in the ore-forming system were restricted by the heterogeneity of lithospheric structure, resulting in effects in different aspects, such as texture, tectonics and evolution. The occurrences and processes of deposit concentration region in Jiaodong were basically controlled by the transformation of tectonic regimes. The deposit concentration region is located in the down-warping area of the mantle upwelling zone, but gold deposits are located in gradient-variation and deformation places of Mohole. The major mineralization intensity is located at the junction between down-warping and upward region, while the minor one is located in the upward district of the upward region. The down-warping area of the mantle is related to the tectonic regime of compression, but the local deformation following the down-warping is connected with the tectonic regime of extension. The gold deposits, controlled by large deep seated faults and shear belts, are mainly distributed near the gradient belts of gravity anomaly and the brink of sub aeromagnetic anomaly regions, the junction between thinning positions of granites and metamorphic rocks. The Tancheng-Lujiang fault is a mature lithosphere fault of deep mantle cut, and also a fluid bearing mantle shear zone. Because of long term reduction of lithospheric thickness, the asthenosphere enriched with fluid components and metallogenic elements, occurred under the Tancheng-Lujiang fault where occurred the coupling of fluid-heat-chemistry-physics. The shear anatexis of the fault was responsible for the lithogenesis and mineralization, and also for the ore forming reactivation and migration. The mantle ore-fluid system was migrated to the upper horizon through this solution divergence and migration along the Tancheng-Lujiang fault in the middle-late Indo-Chinese epoch when the alteration and mineralization took place. The uniqueness of the tectonic position of the Aishan pluton shows that the Aishan pluton might be the center of the convection and intrusion displacement of the crustal mantle magma.
The information of geophysical field was, based on the results of 1∶1 000 00 aeromagnetic anomaly and 1∶2 000 00 Bouguer gravity anomaly in Jiaodong and its neighboring regions, Shandong, China, divided into two parts: deep-and shallow focus-field. The information of the two different fields was then combined with these of wave velocity anisotropy and deep-seated geology. The integrated result was adapted to the analysis of the three-dimension structure, the probe into deep seated mineralization and the dynamics of ore-forming system. This research indicated that the interaction and conversion of materials and energy in the ore-forming system were restricted by the heterogeneity of lithospheric structure, resulting in effects in different aspects, such as texture, tectonics and evolution. The occurrences and processes of deposit concentration region in Jiaodong were basically controlled by the transformation of tectonic regimes. The deposit concentration region is located in the down-warping area of the mantle upwelling zone, but gold deposits are located in gradient-variation and deformation places of Mohole. The major mineralization intensity is located at the junction between down-warping and upward region, while the minor one is located in the upward district of the upward region. The down-warping area of the mantle is related to the tectonic regime of compression, but the local deformation following the down-warping is connected with the tectonic regime of extension. The gold deposits, controlled by large deep seated faults and shear belts, are mainly distributed near the gradient belts of gravity anomaly and the brink of sub aeromagnetic anomaly regions, the junction between thinning positions of granites and metamorphic rocks. The Tancheng-Lujiang fault is a mature lithosphere fault of deep mantle cut, and also a fluid bearing mantle shear zone. Because of long term reduction of lithospheric thickness, the asthenosphere enriched with fluid components and metallogenic elements, occurred under the Tancheng-Lujiang fault where occurred the coupling of fluid-heat-chemistry-physics. The shear anatexis of the fault was responsible for the lithogenesis and mineralization, and also for the ore forming reactivation and migration. The mantle ore-fluid system was migrated to the upper horizon through this solution divergence and migration along the Tancheng-Lujiang fault in the middle-late Indo-Chinese epoch when the alteration and mineralization took place. The uniqueness of the tectonic position of the Aishan pluton shows that the Aishan pluton might be the center of the convection and intrusion displacement of the crustal mantle magma.
2000, 25(4): 428-432.
Abstract:
In a metallogenic system, tectonism and fluid process occurred at the same time and therefore, they are coupled with each other. The action of ore-forming fluids is bound up with formation and evolution of ore-controlling structures. Structural-fluid temporal-spatial evolution track is, in essence, the mobilization, migration, aggregation and location process of ore-forming materials, i.e. the coupled process of structural fluid mineralization. In this paper, the geological analysis for the gold-deposit concentration region of Jiaodong, Shandong Province, China, is conducted with the Gresens' equation, Grant's isocon diagram and O'hara microelement calculation method, to reveal the interactions among the shear tectonic deformation, the wall-rock alteration, mass transfer and gold mineralization. The research results show that the shear deformation and hydrothermal alteration not only include the deformational condition, feature and mechanism of the shear zone, but also are related to the formation, component, flow or circulation model and flux of the fluids in the zone, resulting in the reallocation of elements and the migration of the chemical materials. During the shear-alteration process in the Jiaodong gold concentration area, all kinds of components were transferred in different amounts, the fluid-rock ratio was relatively high and the volume strain was of dilation type. The major reason for this mineralization is the mobilization, migration and enrichment of ore-forming elements induced by the shear compressive-extensional tectonism. The low-grade ores dominated by the inclusion gold were formed in the early ore-forming stage, while the high grade ores containing fissure gold and polymetallic veinlets were formed in the late ore-forming stage.
In a metallogenic system, tectonism and fluid process occurred at the same time and therefore, they are coupled with each other. The action of ore-forming fluids is bound up with formation and evolution of ore-controlling structures. Structural-fluid temporal-spatial evolution track is, in essence, the mobilization, migration, aggregation and location process of ore-forming materials, i.e. the coupled process of structural fluid mineralization. In this paper, the geological analysis for the gold-deposit concentration region of Jiaodong, Shandong Province, China, is conducted with the Gresens' equation, Grant's isocon diagram and O'hara microelement calculation method, to reveal the interactions among the shear tectonic deformation, the wall-rock alteration, mass transfer and gold mineralization. The research results show that the shear deformation and hydrothermal alteration not only include the deformational condition, feature and mechanism of the shear zone, but also are related to the formation, component, flow or circulation model and flux of the fluids in the zone, resulting in the reallocation of elements and the migration of the chemical materials. During the shear-alteration process in the Jiaodong gold concentration area, all kinds of components were transferred in different amounts, the fluid-rock ratio was relatively high and the volume strain was of dilation type. The major reason for this mineralization is the mobilization, migration and enrichment of ore-forming elements induced by the shear compressive-extensional tectonism. The low-grade ores dominated by the inclusion gold were formed in the early ore-forming stage, while the high grade ores containing fissure gold and polymetallic veinlets were formed in the late ore-forming stage.
2000, 25(4): 433-437.
Abstract:
A comprehensive contrast in the metallogenic geological background and metallogenic fluid feature, especially fluid metallogeny has been performed between the Tianmashan and the Datuanshan ore deposits, Tongling, Anhui. The major reasons for the formation of the stratabound skarn Au S ore deposit in Tianmashan and for that of the stratabound skarn Cu ore deposit in Datuanshan are analysed in accordance with this contrast. The magmatic pluton in Tianmashan is rich in Au and poor in Cu, but that in Datuanshan is rich in Cu and Au. The wallrock strata in Tianmashan contain Au bearing pyrite layers with some organic substance but those in Datuanshan contain no such layers. Moreover, the metallogenic fluid in Tianmashan is dominated by magmatic fluid in the major metallogenic stage, but that with high content of Cu in Datuanshan by groundwater fluid. These three contrasts account for the formation of the stratabound skarn Au S ore deposit in Tianmashan and that of the stratabound skarn Cu ore deposit in Datuanshan. In addition, the differences between compositional evolution and physico chemical condition variation of the metallogenic fluid resulting in gradual dispersing of Cu or Au in the late stage of the fluid metallogeny is also an important cause for the generation of the stratabound skarn Au S ore deposit in Tianmashan and that of the stratabound skarn Cu ore deposit in Datuanshan.
A comprehensive contrast in the metallogenic geological background and metallogenic fluid feature, especially fluid metallogeny has been performed between the Tianmashan and the Datuanshan ore deposits, Tongling, Anhui. The major reasons for the formation of the stratabound skarn Au S ore deposit in Tianmashan and for that of the stratabound skarn Cu ore deposit in Datuanshan are analysed in accordance with this contrast. The magmatic pluton in Tianmashan is rich in Au and poor in Cu, but that in Datuanshan is rich in Cu and Au. The wallrock strata in Tianmashan contain Au bearing pyrite layers with some organic substance but those in Datuanshan contain no such layers. Moreover, the metallogenic fluid in Tianmashan is dominated by magmatic fluid in the major metallogenic stage, but that with high content of Cu in Datuanshan by groundwater fluid. These three contrasts account for the formation of the stratabound skarn Au S ore deposit in Tianmashan and that of the stratabound skarn Cu ore deposit in Datuanshan. In addition, the differences between compositional evolution and physico chemical condition variation of the metallogenic fluid resulting in gradual dispersing of Cu or Au in the late stage of the fluid metallogeny is also an important cause for the generation of the stratabound skarn Au S ore deposit in Tianmashan and that of the stratabound skarn Cu ore deposit in Datuanshan.
2000, 25(4): 438-442.
Abstract:
The ore forming fluid, a medium that absorbs, transports and precipitates mineral materials, is an important topic for the research into the contemporary basin and mineralization. The testing analysis is made of the temperature, salinity and chemical composition of the mineral fluid inclusions in the deposit, on the basis of the field geological research into mineral deposits, the indoor microscopic research and geochemical research. The testing analytical results show that Fankou ore bearing fluid, the intermediate low temperature hydrothermal liquid low in salinity and weak in acidity, belongs to K+-Ca2+-Cl- types of deep circulating ore bearing fluid rich in CO2. This ore bearing fluid, a specific deep circulating fluid, differs not only from the basin compaction fluid but also from the ore forming fluid in the porphyrite type deposit.
The ore forming fluid, a medium that absorbs, transports and precipitates mineral materials, is an important topic for the research into the contemporary basin and mineralization. The testing analysis is made of the temperature, salinity and chemical composition of the mineral fluid inclusions in the deposit, on the basis of the field geological research into mineral deposits, the indoor microscopic research and geochemical research. The testing analytical results show that Fankou ore bearing fluid, the intermediate low temperature hydrothermal liquid low in salinity and weak in acidity, belongs to K+-Ca2+-Cl- types of deep circulating ore bearing fluid rich in CO2. This ore bearing fluid, a specific deep circulating fluid, differs not only from the basin compaction fluid but also from the ore forming fluid in the porphyrite type deposit.
