The Tongling area is one of the 7 ore-cluster areas in the Middle-Lower Yangtze metallogenic belt, East China, and has tectonically undergone a long-term geologic history from the late Paleozoic continental rifting, t...The Tongling area is one of the 7 ore-cluster areas in the Middle-Lower Yangtze metallogenic belt, East China, and has tectonically undergone a long-term geologic history from the late Paleozoic continental rifting, through the Middle Triassic continent-continent collision to the Jurassic-Cretaceous intracontinental tectono-magmatic activation. The Carboniferous sedimentary-exhalative processes in the area produced widespread massive sulfides with ages of 303-321 Ma, which partly formed massive pyrite-Cu deposits, but mostly provided significant sulfur and metals to the skarn Cu mineralization associated with the Yanshanian felsic intrusions.To understand the Carboniferous submarine hydrothermal system, an area of about 1046 km^2 was chosen to carry out the geological fluid mapping. Associated with massive sulfide formation, footwall sequences 948 m to 1146 m thick, composed of the Lower Silurian-Upper Devonian sandstone, siltstone and thin-layered shale, were widely altered. This hydrothermal alteration is interpreted to reflect largescale hydrothermal fluid flow associated with the late Paleozoic crustal rifting and subsidence. Three hydrothermal alteration types, i.e., deep-level semiconformable siliclfication （S1）, fracture-controlled quartz-sericite-pyrite alteration （S2-3）, and upper-level sub-discordant quartz-sericite-chlorite alteration （D3）, were developed to form distinct zones in the mapped area. About 50-m thick semiconformable silicification zones are located at -1-km depth below massive sulfides and developed between an impermeable shale caprock （S1） and the underlying Ordovician unaltered limestone. Comparisons with modern geothermal systems suggest that the alteration zones record a sub-seafioor aquifer with the most productive hydrothermal fluid flow. Fracture-controlled quartz-sericite-pyrite alteration formed transgressive zones, which downward crosscut the semiconformable alteration zones, and upwards grade into sub-discordant alteration zones that enveloped no economic string展开更多
Micromotion is the daily tiny vibration of the earth</span><span style="font-family:Verdana;">’</span><span style="font-family:Verdana;">s surface. Micromotional exploratio...Micromotion is the daily tiny vibration of the earth</span><span style="font-family:Verdana;">’</span><span style="font-family:Verdana;">s surface. Micromotional exploration can use the surface wave information of micro motion to study the shallow structure of underground media. In this study, we collected microtremor data at 68 stations in the Middle-Lower Yangtze Metallogenic Belt (MLYMB) and determined the resonant frequency and obtained the distribution of sedimentary thickness in this area by using H/V spectral ratio. According to the results of H/V, the sedimentary layer in the basin is thick, and the predominant frequency of the basin is 0.05</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">0.1</span><span style="font-family:""> </span><span style="font-family:Verdana;">Hz. There are no obvious lateral changes in the impedance interface between bedrock and sedimentary layer in this area. The basement of Tongling, Anqing and Luzhou mining areas and their adjacent areas is Kongling-Dongling type basement, which is composed of a set of metamorphic core complex. The predominant frequency is 0.05</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">0.1</span><span style="font-family:""> </span><span style="font-family:Verdana;">Hz. The sedimentary thickness gradually thinned from 3800</span><span style="font-family:""> </span><span style="font-family:Verdana;">m in the west to 2100</span><span style="font-family:""> </span><span style="font-family:Verdana;">m in the East. Moreover, this article used SPAC (spatial autocorrelation) method to obtain the S-wave velocity structure of the mining area near Luzong. The SPAC method reveals that the depth of the interface between the loose sediments and the volcanic rocks is about 600 m in the study area near the Luzhou mining area in the Middle-Lower Yangtze Met展开更多
文摘The Tongling area is one of the 7 ore-cluster areas in the Middle-Lower Yangtze metallogenic belt, East China, and has tectonically undergone a long-term geologic history from the late Paleozoic continental rifting, through the Middle Triassic continent-continent collision to the Jurassic-Cretaceous intracontinental tectono-magmatic activation. The Carboniferous sedimentary-exhalative processes in the area produced widespread massive sulfides with ages of 303-321 Ma, which partly formed massive pyrite-Cu deposits, but mostly provided significant sulfur and metals to the skarn Cu mineralization associated with the Yanshanian felsic intrusions.To understand the Carboniferous submarine hydrothermal system, an area of about 1046 km^2 was chosen to carry out the geological fluid mapping. Associated with massive sulfide formation, footwall sequences 948 m to 1146 m thick, composed of the Lower Silurian-Upper Devonian sandstone, siltstone and thin-layered shale, were widely altered. This hydrothermal alteration is interpreted to reflect largescale hydrothermal fluid flow associated with the late Paleozoic crustal rifting and subsidence. Three hydrothermal alteration types, i.e., deep-level semiconformable siliclfication （S1）, fracture-controlled quartz-sericite-pyrite alteration （S2-3）, and upper-level sub-discordant quartz-sericite-chlorite alteration （D3）, were developed to form distinct zones in the mapped area. About 50-m thick semiconformable silicification zones are located at -1-km depth below massive sulfides and developed between an impermeable shale caprock （S1） and the underlying Ordovician unaltered limestone. Comparisons with modern geothermal systems suggest that the alteration zones record a sub-seafioor aquifer with the most productive hydrothermal fluid flow. Fracture-controlled quartz-sericite-pyrite alteration formed transgressive zones, which downward crosscut the semiconformable alteration zones, and upwards grade into sub-discordant alteration zones that enveloped no economic string
文摘Micromotion is the daily tiny vibration of the earth</span><span style="font-family:Verdana;">’</span><span style="font-family:Verdana;">s surface. Micromotional exploration can use the surface wave information of micro motion to study the shallow structure of underground media. In this study, we collected microtremor data at 68 stations in the Middle-Lower Yangtze Metallogenic Belt (MLYMB) and determined the resonant frequency and obtained the distribution of sedimentary thickness in this area by using H/V spectral ratio. According to the results of H/V, the sedimentary layer in the basin is thick, and the predominant frequency of the basin is 0.05</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">0.1</span><span style="font-family:""> </span><span style="font-family:Verdana;">Hz. There are no obvious lateral changes in the impedance interface between bedrock and sedimentary layer in this area. The basement of Tongling, Anqing and Luzhou mining areas and their adjacent areas is Kongling-Dongling type basement, which is composed of a set of metamorphic core complex. The predominant frequency is 0.05</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">0.1</span><span style="font-family:""> </span><span style="font-family:Verdana;">Hz. The sedimentary thickness gradually thinned from 3800</span><span style="font-family:""> </span><span style="font-family:Verdana;">m in the west to 2100</span><span style="font-family:""> </span><span style="font-family:Verdana;">m in the East. Moreover, this article used SPAC (spatial autocorrelation) method to obtain the S-wave velocity structure of the mining area near Luzong. The SPAC method reveals that the depth of the interface between the loose sediments and the volcanic rocks is about 600 m in the study area near the Luzhou mining area in the Middle-Lower Yangtze Met
