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Study on the Ore-forming condition and occurrence of uranium minerals in sandstone-type uranium deposits from Ordos basin, Northwest China
A720
Goldschmidt Conference Abstracts 2006
40
Ar/39Ar Dating on Mylonites in the ductile shear zones from South Tan-Lu fault belt in Anhui Province, East China
Study on the Ore-forming condition and occurrence of uranium minerals in sandstone-type uranium deposits from Ordos basin, Northwest China
X.Y. YANG CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University Science and Technology of China, Hefei 230026, China (xyyang@ ustc.edu.cn) The area for this study is in the joint part of Tan-Lu fault belt with the East Qinling–Dabie orogenic belt in east part of China (Mattauer et al., 1985). Tan-Lu fault belt is an important deep fault belt in east China and Asian continent, and its southern part is the key part for geology, where the mylonites were developed in the ductile shear zones since its shifting movement, and the plastic deformation are commonly occurring in the mylonites. In this study, the 40Ar/39Ar age of several kinds of deformed minerals have been obtained to illustrate the evolution of the ductile shear zones and formation of mylonites in this region.
Methods The biotite and plagioclase samples separated from the mylonites were determined by40Ar/39Ar fast neutron activation technique in the Institute of Geology and Geophysics, CAS. Some deformed minerals such as biotite and feldspar can record the chronological information since the period of ductile shearing event, these ages from the deformed minerals may represent the important period of the history of deformation caused by the shifting movement of Tan-Lu fault belt.
Results Finally, five ages from single deformed minerals were obtained with the plateau ages of 98, 109, 104, 106 and 113 Ma, respectively. These ages represent the cooling time accompanying formation of mylonites, when the large scale of shifting movement of TanLu fault belt occurred after the collision of Yangtze block and North China block since Triassic, which accords with the former studies in Dabie–Sulu region.
Acknowledgment This study is supported by the National Science Foundation of China (40473021).
Reference Mattauer, M., Matte, Ph., Malavielle, J., Tappomier, P., Aluski, Xu, Z., Liu, Y., Tang, Y., 1985. Tectonics of the Qinling belt, building up and evolution of East Asia. Nature 317, 496–500. doi:10.1016/j.gca.2006.06.1292
X.Y. YANG1, M.X. LING1, W. SUN2, C.Y. LIU2 1
CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University Science and Technology of China, Hefei 230026, China (xyyang@ ustc.edu.cn) 2 Department of Geology, Northwest University, Xi’an 710069, China
Introduction The Ordos basin is the second largest sedimentary basins in China. The present Ordos basin is attributed to be a remnant craton basin in the Mesozoic (Darby and Ritts, 2002). With the development of oil and natural gas exploration, the breakthrough of sandstone-type uranium deposit in the northern part of the basin has been achieved in this basin.
Results Sandstone-type uranium deposit is one of uranium deposits with industrial value (Granger et al., 1961). This study focuses on forming condition and occurrence of sandstone-type uranium deposits by the jointed research with fluid inclusion analysis and high-resolution SEM and EPMA. Fluid inclusion shows that the two major mineralization temperature ranges of 140–180 °C and 100–120 °C, respectively. The sanity of the fluid inclusions is mainly ranging from 4 to 10 wt% (NaCl) with multiple climaxes in different drilling holes. Most of H and O isotopic data fall into the region of formation water, parts belong to metamorphic water. The SEM and EPMA results show that most of the uranium minerals are in micro-grained distributed in potassic feldspar, microcline, quartz, muscovite and cement in the form of very tiny grains (<1 lm) with different contents of UO2 ranging from 0 to several percentages.
Acknowledgment This study is supported by Chinese National Key Research and Development Program (2003CB214606).
References Darby, B.J., Ritts, B.D., 2002. Mesozoic contractional deformation in the middle of the Asian tectonic collage: the intraplate Western Ordos fold–thrust belt, China. Earth Planet. Sci. Lett. 205, 13–24. Granger, H.C., Santos, E.S., Dean, B.G., Moore, F.B., 1961. Sandstonetype uranium deposits at Ambrosia Lake, New Mexico—an interim report. Econ. Geol. 56, 1179–1209. doi:10.1016/j.gca.2006.06.1293
Goldschmidt Conference Abstracts 2006
40
Ar/39Ar Dating on Mylonites in the ductile shear zones from South Tan-Lu fault belt in Anhui Province, East China
Study on the Ore-forming condition and occurrence of uranium minerals in sandstone-type uranium deposits from Ordos basin, Northwest China
X.Y. YANG CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University Science and Technology of China, Hefei 230026, China (xyyang@ ustc.edu.cn) The area for this study is in the joint part of Tan-Lu fault belt with the East Qinling–Dabie orogenic belt in east part of China (Mattauer et al., 1985). Tan-Lu fault belt is an important deep fault belt in east China and Asian continent, and its southern part is the key part for geology, where the mylonites were developed in the ductile shear zones since its shifting movement, and the plastic deformation are commonly occurring in the mylonites. In this study, the 40Ar/39Ar age of several kinds of deformed minerals have been obtained to illustrate the evolution of the ductile shear zones and formation of mylonites in this region.
Methods The biotite and plagioclase samples separated from the mylonites were determined by40Ar/39Ar fast neutron activation technique in the Institute of Geology and Geophysics, CAS. Some deformed minerals such as biotite and feldspar can record the chronological information since the period of ductile shearing event, these ages from the deformed minerals may represent the important period of the history of deformation caused by the shifting movement of Tan-Lu fault belt.
Results Finally, five ages from single deformed minerals were obtained with the plateau ages of 98, 109, 104, 106 and 113 Ma, respectively. These ages represent the cooling time accompanying formation of mylonites, when the large scale of shifting movement of TanLu fault belt occurred after the collision of Yangtze block and North China block since Triassic, which accords with the former studies in Dabie–Sulu region.
Acknowledgment This study is supported by the National Science Foundation of China (40473021).
Reference Mattauer, M., Matte, Ph., Malavielle, J., Tappomier, P., Aluski, Xu, Z., Liu, Y., Tang, Y., 1985. Tectonics of the Qinling belt, building up and evolution of East Asia. Nature 317, 496–500. doi:10.1016/j.gca.2006.06.1292
X.Y. YANG1, M.X. LING1, W. SUN2, C.Y. LIU2 1
CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University Science and Technology of China, Hefei 230026, China (xyyang@ ustc.edu.cn) 2 Department of Geology, Northwest University, Xi’an 710069, China
Introduction The Ordos basin is the second largest sedimentary basins in China. The present Ordos basin is attributed to be a remnant craton basin in the Mesozoic (Darby and Ritts, 2002). With the development of oil and natural gas exploration, the breakthrough of sandstone-type uranium deposit in the northern part of the basin has been achieved in this basin.
Results Sandstone-type uranium deposit is one of uranium deposits with industrial value (Granger et al., 1961). This study focuses on forming condition and occurrence of sandstone-type uranium deposits by the jointed research with fluid inclusion analysis and high-resolution SEM and EPMA. Fluid inclusion shows that the two major mineralization temperature ranges of 140–180 °C and 100–120 °C, respectively. The sanity of the fluid inclusions is mainly ranging from 4 to 10 wt% (NaCl) with multiple climaxes in different drilling holes. Most of H and O isotopic data fall into the region of formation water, parts belong to metamorphic water. The SEM and EPMA results show that most of the uranium minerals are in micro-grained distributed in potassic feldspar, microcline, quartz, muscovite and cement in the form of very tiny grains (<1 lm) with different contents of UO2 ranging from 0 to several percentages.
Acknowledgment This study is supported by Chinese National Key Research and Development Program (2003CB214606).
References Darby, B.J., Ritts, B.D., 2002. Mesozoic contractional deformation in the middle of the Asian tectonic collage: the intraplate Western Ordos fold–thrust belt, China. Earth Planet. Sci. Lett. 205, 13–24. Granger, H.C., Santos, E.S., Dean, B.G., Moore, F.B., 1961. Sandstonetype uranium deposits at Ambrosia Lake, New Mexico—an interim report. Econ. Geol. 56, 1179–1209. doi:10.1016/j.gca.2006.06.1293