Trachytic rock and its altered rock—fenite—in the Bayan Obo ore district, Inner Mongolia, China, were referred to as slate or feldspar rock before, and identified by the authors for the first time (in 1992). In the ...Trachytic rock and its altered rock—fenite—in the Bayan Obo ore district, Inner Mongolia, China, were referred to as slate or feldspar rock before, and identified by the authors for the first time (in 1992). In the paper the mineral assemblages, structures and textures and petrochemical compositions of the rocks, as well as the electron microprobe analysis of feldspars in the rocks are described. The Sm-Nd isochron age of the trachytic rock is 1096 ± 56 Ma, with INd=0.51100±4 (2 s?) and ?Nd(t)= ?4.4 ± 0.7. Alterations of the trachytic rock, including microclinization, riebeckitization, aegirinization and biotitization, and accompanied rare element and REE mineralizations are discussed. Based on the occurrence of the trachytic rock and associated fenitization it is deduced that the Bayan Obo Fe-Nb-REE ore deposit is genetically related to magmatic-hydrothermal activity of an alkali carbonatite complex.展开更多
The Maoniuping REE deposit, located about 22 km to the southwest of Mianning, Sichuan Province, is the second largest light REE deposit in China, subsequent to the Bayan Obo Fe-Nb-REE deposit in the Inner Mongolia Aut...The Maoniuping REE deposit, located about 22 km to the southwest of Mianning, Sichuan Province, is the second largest light REE deposit in China, subsequent to the Bayan Obo Fe-Nb-REE deposit in the Inner Mongolia Autonomous Region. Tectonically, it is located in the transitional zone between the Panxi rift and the Longmenshan-Jinpingshan orogenic zone. It is a carbonatite vein-type deposit hosted in alkaline complex rocks. The bastnaesite-barite, bastnaesite-calcite, and bastnaesite- microcline lodes are the main three types of REE ore lodes. Among these, the first lode is distributed most extensively and its REE mineralization is the strongest. The δ^34Sv.cDT values of the barites in the ore of the deposit vary in a narrow range of ＋5.0 to ＋5.1‰ in the bastnaesite-calcite lode and ＋3.3 to ＋5.9‰ in the bastnaesite-barite lode, showing the isotopic characteristics of magma-derived sulfur. The δ^13Cv-PDB values and the δ^Ov.SMOW values in the bastnaesite-calcite lode range from -3.9 to -6.9‰ and from ＋7.3 to ＋9.7 ‰, respectively, which fall into the range of ＂primary carbonatltes＂, showing that carbon and oxygen in the ores of the Maoniuping deposit were derived mainly from a deep source. The δ^13Cv.PDB values of fluid inclusions vary from -3.0 to -5.6‰, with -3.0 to -4.0‰ in the bastnaesitecalcite lode and -3.0 to -5.6‰ in the bastnaesite-barite lode, which show characteristics of mantle- derived carbon. The δDv-SMOW values of fluid inclusions range from -57 to -88‰, with -63 to -86‰ in the bastnaesite-calcite lode and -57 to -88‰ in the bastnaesite-barite lode, which show characteristics of mantle-derived hydrogen. The δ^18OH2OV.SMOW values vary from ＋7.4 to ＋8.6‰ in the bastnaesitecalcite lode, and ＋6.7 to ＋7.8‰ in the bastnaesite-barite lode, almost overlapping the range of ＋5.5 to ＋9.5‰ for magmatic water. The 4He content, R/Ra ratios are （13.95 to 119.58）×10^-6 （cm^3/g）STP and 0.02 to 0.11, respectively, and ^40Ar/^36Ar is 313± 1 to 437 ± 2. Considering the 4He increase caused by high contents of radioactive elements, a mantle-derived fluid probably exists in the inclusions in the fluorite, calcite and bastnaesite samples. The Maoniuping deposit and its associated carbonatite-alkaline complex were formed in 40.3 to 12.2 Ma according to K-Ar and U-Pb data. All these data suggest that large quantities of mantle fluids were involved in the metallogenic process of the Maoniuping REE deposit through a fault system.展开更多
: On the basis of the geological data from 220 intrusions and isotope ages of 115 rock bodies, the paper discusses the distribution of 18 alkaline intrusive rock belts along deep faults and their relations to the plat...: On the basis of the geological data from 220 intrusions and isotope ages of 115 rock bodies, the paper discusses the distribution of 18 alkaline intrusive rock belts along deep faults and their relations to the plate tectonic activity. In view of the presence of a large amount of Variscan alkaline rocks of deep-source character, it is inferred that mantle diapirism was very strong in China during the Variscan. Besides anorogenic and postorogenic alkaline granites, there also occur alkaline granites formed in the terminal orogenic stage when the regional tectonic activity was of compressional nature. Finally, the paper discusses the tectonic environment of the Maoniuping nordmarkite in Mianning county, Sichuan province, and the authors consider it to be a compressional environment originating after rift closing.展开更多
This paper proposed a procedure of handling a remote rainwater sample to determinethe PH values of the samples immediately after collecting. Then the initial chemical composition inthe stored rainwater was estimated b...This paper proposed a procedure of handling a remote rainwater sample to determinethe PH values of the samples immediately after collecting. Then the initial chemical composition inthe stored rainwater was estimated by a regression model.展开更多
文摘Trachytic rock and its altered rock—fenite—in the Bayan Obo ore district, Inner Mongolia, China, were referred to as slate or feldspar rock before, and identified by the authors for the first time (in 1992). In the paper the mineral assemblages, structures and textures and petrochemical compositions of the rocks, as well as the electron microprobe analysis of feldspars in the rocks are described. The Sm-Nd isochron age of the trachytic rock is 1096 ± 56 Ma, with INd=0.51100±4 (2 s?) and ?Nd(t)= ?4.4 ± 0.7. Alterations of the trachytic rock, including microclinization, riebeckitization, aegirinization and biotitization, and accompanied rare element and REE mineralizations are discussed. Based on the occurrence of the trachytic rock and associated fenitization it is deduced that the Bayan Obo Fe-Nb-REE ore deposit is genetically related to magmatic-hydrothermal activity of an alkali carbonatite complex.
文摘The Maoniuping REE deposit, located about 22 km to the southwest of Mianning, Sichuan Province, is the second largest light REE deposit in China, subsequent to the Bayan Obo Fe-Nb-REE deposit in the Inner Mongolia Autonomous Region. Tectonically, it is located in the transitional zone between the Panxi rift and the Longmenshan-Jinpingshan orogenic zone. It is a carbonatite vein-type deposit hosted in alkaline complex rocks. The bastnaesite-barite, bastnaesite-calcite, and bastnaesite- microcline lodes are the main three types of REE ore lodes. Among these, the first lode is distributed most extensively and its REE mineralization is the strongest. The δ^34Sv.cDT values of the barites in the ore of the deposit vary in a narrow range of ＋5.0 to ＋5.1‰ in the bastnaesite-calcite lode and ＋3.3 to ＋5.9‰ in the bastnaesite-barite lode, showing the isotopic characteristics of magma-derived sulfur. The δ^13Cv-PDB values and the δ^Ov.SMOW values in the bastnaesite-calcite lode range from -3.9 to -6.9‰ and from ＋7.3 to ＋9.7 ‰, respectively, which fall into the range of ＂primary carbonatltes＂, showing that carbon and oxygen in the ores of the Maoniuping deposit were derived mainly from a deep source. The δ^13Cv.PDB values of fluid inclusions vary from -3.0 to -5.6‰, with -3.0 to -4.0‰ in the bastnaesitecalcite lode and -3.0 to -5.6‰ in the bastnaesite-barite lode, which show characteristics of mantle- derived carbon. The δDv-SMOW values of fluid inclusions range from -57 to -88‰, with -63 to -86‰ in the bastnaesite-calcite lode and -57 to -88‰ in the bastnaesite-barite lode, which show characteristics of mantle-derived hydrogen. The δ^18OH2OV.SMOW values vary from ＋7.4 to ＋8.6‰ in the bastnaesitecalcite lode, and ＋6.7 to ＋7.8‰ in the bastnaesite-barite lode, almost overlapping the range of ＋5.5 to ＋9.5‰ for magmatic water. The 4He content, R/Ra ratios are （13.95 to 119.58）×10^-6 （cm^3/g）STP and 0.02 to 0.11, respectively, and ^40Ar/^36Ar is 313± 1 to 437 ± 2. Considering the 4He increase caused by high contents of radioactive elements, a mantle-derived fluid probably exists in the inclusions in the fluorite, calcite and bastnaesite samples. The Maoniuping deposit and its associated carbonatite-alkaline complex were formed in 40.3 to 12.2 Ma according to K-Ar and U-Pb data. All these data suggest that large quantities of mantle fluids were involved in the metallogenic process of the Maoniuping REE deposit through a fault system.
文摘: On the basis of the geological data from 220 intrusions and isotope ages of 115 rock bodies, the paper discusses the distribution of 18 alkaline intrusive rock belts along deep faults and their relations to the plate tectonic activity. In view of the presence of a large amount of Variscan alkaline rocks of deep-source character, it is inferred that mantle diapirism was very strong in China during the Variscan. Besides anorogenic and postorogenic alkaline granites, there also occur alkaline granites formed in the terminal orogenic stage when the regional tectonic activity was of compressional nature. Finally, the paper discusses the tectonic environment of the Maoniuping nordmarkite in Mianning county, Sichuan province, and the authors consider it to be a compressional environment originating after rift closing.
文摘This paper proposed a procedure of handling a remote rainwater sample to determinethe PH values of the samples immediately after collecting. Then the initial chemical composition inthe stored rainwater was estimated by a regression model.
