Our aim is to clarify mud volcanoes from the new mud diapirs resulting from the seismic attributes analysis applied to the low resolution Burmah oil “1973-1974” seismic data. The latter was carried out on the Larach...Our aim is to clarify mud volcanoes from the new mud diapirs resulting from the seismic attributes analysis applied to the low resolution Burmah oil “1973-1974” seismic data. The latter was carried out on the Larache and Tanger-Larache offshores from the NE-SW Atlantic margin. The high resolution seismic data was essential for this evaluation. In this case, we applied seismic signature analysis to four seismic profiles from the map of the seismic data set, which includes all new mud diapirs. This helped us to classify different types of mud diapirs within the seismic profiles. And as a result, six deep mud diapirs from the Prerifaine Nappe of Morocco, a shallow mud diapir, and four seafloor-piercing mud diapirs have been observed. Furthermore, the seafloor-piercing mud diapirs show a mushroom-shaped and conical-shaped cone. As they break through the seafloor, these kinds of cones characterize mud volcanoes. In this case, we may conclude that the resultant seafloor-piercing mud diapirs are likely to be mud volcanoes. However, more geological sampling and seafloor observation are still required.展开更多
The Pb-Zn metallogenic district in NW Guizhou Province is an important part of the Yun-nan-Sichuan-Guizhou Pb-Zn metallogenic province, and also is one of the most important Pb-Zn producers in China. The hosting rocks...The Pb-Zn metallogenic district in NW Guizhou Province is an important part of the Yun-nan-Sichuan-Guizhou Pb-Zn metallogenic province, and also is one of the most important Pb-Zn producers in China. The hosting rocks of the Pb-Zn deposits are Devonian to Permian carbonate rocks, and the basement rocks are meta-sedimentary and igneous rocks of the Proterozoic Kunyang and Huili groups. The ore minerals are composed of sphalerite, galena and pyrite, and the gangue minerals are include calcite and dolomite. Geology and C-O isotope of these deposits were studied in this paper. The results show that δ13C and δ18O values of hydrothermal calcite, altered wall rocks-dolostone, sedimentary calcite and hosting carbonate rocks range from -5.3‰ to -0.6 ‰ (mean -3.4‰) and +11.3‰ to +20.9 ‰ (mean +17.2‰), -3.0‰ to +0.9 ‰ (mean -1.3‰) and +17.0‰ to +20.8‰ (mean +19.7‰), +0.6‰ to +2.5 ‰ (mean +1.4‰) and +23.4‰ to +26.5 ‰ (mean +24.6‰), and -1.8‰ to +3.9‰ (mean +0.7‰) and +21.0‰ to +26.8‰ (mean +22.9‰), respectively, implying that CO2 in the ore-forming fluids was mainly a result of dissolution of Devonian and Carboniferous carbonate rocks. However, it is difficult to evaluate the contribution of sediment de-hydroxylation. Based on the integrated analysis of geology, C and O isotopes, it is believed that the ore-forming fluids of these carbonate-hosted Pb-Zn deposits in this area were derived from multiple sources, including hosting carbonate rocks, Devonian to Permian sedimentary rocks and basement rocks (the Kun-yang and Huili groups). Therefore, the fluids mixing is the main precipitation mechanism of the Pb-Zn deposit in this province.展开更多
基金《国土资源部大陆动力学重点实验室》(Key Laboratory of Continental Dynamics,MLRInstitutes of Geology,Chinese Academy of Geological Sciences,Beijing,China)和国家科技专项《汶川地震断裂带科学钻探》(WFSD)项目研究成果
文摘Our aim is to clarify mud volcanoes from the new mud diapirs resulting from the seismic attributes analysis applied to the low resolution Burmah oil “1973-1974” seismic data. The latter was carried out on the Larache and Tanger-Larache offshores from the NE-SW Atlantic margin. The high resolution seismic data was essential for this evaluation. In this case, we applied seismic signature analysis to four seismic profiles from the map of the seismic data set, which includes all new mud diapirs. This helped us to classify different types of mud diapirs within the seismic profiles. And as a result, six deep mud diapirs from the Prerifaine Nappe of Morocco, a shallow mud diapir, and four seafloor-piercing mud diapirs have been observed. Furthermore, the seafloor-piercing mud diapirs show a mushroom-shaped and conical-shaped cone. As they break through the seafloor, these kinds of cones characterize mud volcanoes. In this case, we may conclude that the resultant seafloor-piercing mud diapirs are likely to be mud volcanoes. However, more geological sampling and seafloor observation are still required.
基金financially supported jointly by the National Natural Science Foundation of China (Grant Nos. 41102055and 41102053)the National Basic Research Program of China (Grant No. 2007CB411402)
文摘The Pb-Zn metallogenic district in NW Guizhou Province is an important part of the Yun-nan-Sichuan-Guizhou Pb-Zn metallogenic province, and also is one of the most important Pb-Zn producers in China. The hosting rocks of the Pb-Zn deposits are Devonian to Permian carbonate rocks, and the basement rocks are meta-sedimentary and igneous rocks of the Proterozoic Kunyang and Huili groups. The ore minerals are composed of sphalerite, galena and pyrite, and the gangue minerals are include calcite and dolomite. Geology and C-O isotope of these deposits were studied in this paper. The results show that δ13C and δ18O values of hydrothermal calcite, altered wall rocks-dolostone, sedimentary calcite and hosting carbonate rocks range from -5.3‰ to -0.6 ‰ (mean -3.4‰) and +11.3‰ to +20.9 ‰ (mean +17.2‰), -3.0‰ to +0.9 ‰ (mean -1.3‰) and +17.0‰ to +20.8‰ (mean +19.7‰), +0.6‰ to +2.5 ‰ (mean +1.4‰) and +23.4‰ to +26.5 ‰ (mean +24.6‰), and -1.8‰ to +3.9‰ (mean +0.7‰) and +21.0‰ to +26.8‰ (mean +22.9‰), respectively, implying that CO2 in the ore-forming fluids was mainly a result of dissolution of Devonian and Carboniferous carbonate rocks. However, it is difficult to evaluate the contribution of sediment de-hydroxylation. Based on the integrated analysis of geology, C and O isotopes, it is believed that the ore-forming fluids of these carbonate-hosted Pb-Zn deposits in this area were derived from multiple sources, including hosting carbonate rocks, Devonian to Permian sedimentary rocks and basement rocks (the Kun-yang and Huili groups). Therefore, the fluids mixing is the main precipitation mechanism of the Pb-Zn deposit in this province.
