Tectonic dynamic system transition, one of the main factors in metallogenesis, controls metallogenic fluid movement and ore body location in orefields and on an ore deposit scale (mainly in the continental tectonic se...Tectonic dynamic system transition, one of the main factors in metallogenesis, controls metallogenic fluid movement and ore body location in orefields and on an ore deposit scale (mainly in the continental tectonic setting), and even the formation and distribution of large-scale deposit clusters. Tectonic dynamic system transition can be classified as the spacious difference of the tectonic dynamic system in various geological units and the temporal alteration of different tectonic dynamic systems. The former results in outburst of mineralization, while the latter leads to the metallogenic diversity. Both of them are the main contents of metallogenic effect of tectonic dynamic system transition, that is, the alteration of dynamic system, the occurrence of mineralization, and the difference of regional tectonic dynamic system and metallogenic diversity. Generally speaking, the coupling of spatial difference of tectonic dynamic system and its successive alternation controlled the tempo-spatial evolution regularity of mineralization on a larger scale. In addition, the analysis of mineralization factors and processes of typical ore deposits proved that the changes of tectonic stress field, the direct appearance of tectonic dynamic system transition, may lead to the accident of mineralization physical-chemical field and the corresponding accidental interfaces were always located at ore bodies.展开更多
The N-S trending Xiaojiang fault zone and the NW-SE trending Qujiang-Shiping fault zone are adjacent active fault systems and seismogenic zones associated with strong and major earthquakes in Yunnan, China. To underst...The N-S trending Xiaojiang fault zone and the NW-SE trending Qujiang-Shiping fault zone are adjacent active fault systems and seismogenic zones associated with strong and major earthquakes in Yunnan, China. To understand the interaction of the two fault systems, and its probable influence on earthquake occurrences, this paper conducts a synthetic study based on data of active tectonics, historical earthquakes, relocated small earthquakes, GPS station velocities and focal mechanism resolutions. The study makes several conclusions. （1） The active southward motion of the western side of the Xiaojiang fault zone （i.e. the side of the Sichuan-Yunnan block） has a persistent and intensive effect on the Qujiang-Shiping fault zone. The later fault zone has absorbed and transformed the southward motion of the western side of the former fault zone through dextral strike-slip/sheafing as well as transverse shortening/thrusting. （2） Along the Xiaojiang fault zone, the present sinistral strike-slip/sheafing rate decreases from 10 and 8 mm/a on the northern, central and central-southern segments to 4 mm/a on the southern segment. The decreased rate has been adjusted in the area along and surrounding the Qujiang-Shiping fault zone through reverse-dextral faulting and distributed sheafing and shortening. （3） The tectonic-dynamic relation between the Xiaojiang fault zone and the Qujiang-Shiping fault zone is also manifested by a close correlation of earthquake occurrences on the two fault zones. From 1500 to 1850 a sequence of strong and major earthquakes occurred along the Xiaojiang fault zone and its northern neighbor, the Zemuhe fault zone, which was characterized by gradually accelerating strain release, gradually shortening intervals between M≥7 events, and major releases occurring in the mid to later stages of the sequence. As a response to this sequence, after an 88-year delay, another sequence of 383 years （from 1588 to 1970） of strong and major earthquakes occurred on the Qujiang-Shiping fault zone, and had the same features in accelerating strain release and its temporal course. （4） Since there has been no M≥7 event for 177 years on the Xiaojiang fault zone, the potential risk of a strong or major earthquake occurring on this fault zone in the future should be noticed and studied further.展开更多
This paper presents a method of establishing a hydrothermal ore-forming reaction system. On the basis of the study of four typical hydrothermal deposits, the folowing conclusions concerning geochemical dynamic control...This paper presents a method of establishing a hydrothermal ore-forming reaction system. On the basis of the study of four typical hydrothermal deposits, the folowing conclusions concerning geochemical dynamic controlling during hydrothermal mineralization have been drawn: (1 ) The regional tectonic activities control the concentration and dispersion of elements in the ore-forming process in terms of their effects on the thermodynamic nature and conditions of the ore-forming reaction system. (2) During hydrothermal mineralization the activities of ore-bearing faults can be divided into two stages: the brittle splitting stage and the brirtle-tough tensing stage, which would create characteristically different geodynamic conditions for the geochemical thermodynamic ore-forming system. (3) The hydrothermal ore-forming reaction system is an open dynamic system. At the brittle splitting stage the system was so strongly supersaturated and unequilibrated as to speed up and enhance the crystallization and differentiation of ore-forming fluids. And at the brittle-tough tensing stage, the ore-forming system was in a weak supersaturated state; with decreasing temperature and pressure the crystallization of oreforming material would slow down, and it can be regarded as an equilibrated state. (4) In the later stages of hydrothermal evolution, gold would be concentrated in the residual ore-forming solution. The pulsating fracture activity in this stage led to the crush of pyrite ore and it was then filled with gold-enriched solution, forming high-grade "fissure" gold ore. This ore-forming process could be called the coupling mechanism of ore formation.展开更多
文摘Tectonic dynamic system transition, one of the main factors in metallogenesis, controls metallogenic fluid movement and ore body location in orefields and on an ore deposit scale (mainly in the continental tectonic setting), and even the formation and distribution of large-scale deposit clusters. Tectonic dynamic system transition can be classified as the spacious difference of the tectonic dynamic system in various geological units and the temporal alteration of different tectonic dynamic systems. The former results in outburst of mineralization, while the latter leads to the metallogenic diversity. Both of them are the main contents of metallogenic effect of tectonic dynamic system transition, that is, the alteration of dynamic system, the occurrence of mineralization, and the difference of regional tectonic dynamic system and metallogenic diversity. Generally speaking, the coupling of spatial difference of tectonic dynamic system and its successive alternation controlled the tempo-spatial evolution regularity of mineralization on a larger scale. In addition, the analysis of mineralization factors and processes of typical ore deposits proved that the changes of tectonic stress field, the direct appearance of tectonic dynamic system transition, may lead to the accident of mineralization physical-chemical field and the corresponding accidental interfaces were always located at ore bodies.
基金supported by the Special Funds for Research of Earthquake Science (Grant No. 200708035)the Special Project M7 of China Earthquake Administration
文摘The N-S trending Xiaojiang fault zone and the NW-SE trending Qujiang-Shiping fault zone are adjacent active fault systems and seismogenic zones associated with strong and major earthquakes in Yunnan, China. To understand the interaction of the two fault systems, and its probable influence on earthquake occurrences, this paper conducts a synthetic study based on data of active tectonics, historical earthquakes, relocated small earthquakes, GPS station velocities and focal mechanism resolutions. The study makes several conclusions. （1） The active southward motion of the western side of the Xiaojiang fault zone （i.e. the side of the Sichuan-Yunnan block） has a persistent and intensive effect on the Qujiang-Shiping fault zone. The later fault zone has absorbed and transformed the southward motion of the western side of the former fault zone through dextral strike-slip/sheafing as well as transverse shortening/thrusting. （2） Along the Xiaojiang fault zone, the present sinistral strike-slip/sheafing rate decreases from 10 and 8 mm/a on the northern, central and central-southern segments to 4 mm/a on the southern segment. The decreased rate has been adjusted in the area along and surrounding the Qujiang-Shiping fault zone through reverse-dextral faulting and distributed sheafing and shortening. （3） The tectonic-dynamic relation between the Xiaojiang fault zone and the Qujiang-Shiping fault zone is also manifested by a close correlation of earthquake occurrences on the two fault zones. From 1500 to 1850 a sequence of strong and major earthquakes occurred along the Xiaojiang fault zone and its northern neighbor, the Zemuhe fault zone, which was characterized by gradually accelerating strain release, gradually shortening intervals between M≥7 events, and major releases occurring in the mid to later stages of the sequence. As a response to this sequence, after an 88-year delay, another sequence of 383 years （from 1588 to 1970） of strong and major earthquakes occurred on the Qujiang-Shiping fault zone, and had the same features in accelerating strain release and its temporal course. （4） Since there has been no M≥7 event for 177 years on the Xiaojiang fault zone, the potential risk of a strong or major earthquake occurring on this fault zone in the future should be noticed and studied further.
文摘This paper presents a method of establishing a hydrothermal ore-forming reaction system. On the basis of the study of four typical hydrothermal deposits, the folowing conclusions concerning geochemical dynamic controlling during hydrothermal mineralization have been drawn: (1 ) The regional tectonic activities control the concentration and dispersion of elements in the ore-forming process in terms of their effects on the thermodynamic nature and conditions of the ore-forming reaction system. (2) During hydrothermal mineralization the activities of ore-bearing faults can be divided into two stages: the brittle splitting stage and the brirtle-tough tensing stage, which would create characteristically different geodynamic conditions for the geochemical thermodynamic ore-forming system. (3) The hydrothermal ore-forming reaction system is an open dynamic system. At the brittle splitting stage the system was so strongly supersaturated and unequilibrated as to speed up and enhance the crystallization and differentiation of ore-forming fluids. And at the brittle-tough tensing stage, the ore-forming system was in a weak supersaturated state; with decreasing temperature and pressure the crystallization of oreforming material would slow down, and it can be regarded as an equilibrated state. (4) In the later stages of hydrothermal evolution, gold would be concentrated in the residual ore-forming solution. The pulsating fracture activity in this stage led to the crush of pyrite ore and it was then filled with gold-enriched solution, forming high-grade "fissure" gold ore. This ore-forming process could be called the coupling mechanism of ore formation.
