ISSN 1006-3021 CN11-3474/P
Published bimonthly started in 1979
投稿时间:2019-09-09  修订日期:2019-10-10
关键词:Volcanic rock series in the south of Lancangjiang  rhyolite  geochemical characteristics  chronology  geological significance  Pu'er area
唐波浪 中国地质大学(北京)自然资源部深地动力学重点实验室,中国地质科学院地质研究所 
刘英超 自然资源部深地动力学重点实验室,中国地质科学院地质研究所 
马旺 自然资源部深地动力学重点实验室,中国地质科学院地质研究所  
岳龙龙 自然资源部深地动力学重点实验室,中国地质科学院地质研究所  
黄世强 中国地质大学(北京)  
庄亮亮 自然资源部深地动力学重点实验室,中国地质科学院地质研究所  
吴志旖 中国地质大学(北京)  
周梦林 山东省地质测绘院  
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The existence of the Jurassic volcanic rocks in the southern part of the Lancangjiang belt and its geological significance
      The volcanic rock series in the south of the Lancangjiang is a product of the evolution of the Paleo-Tethys and it’s a tool for inverting the evolution of the Paleo-Tethys. This paper selects the systematic chronology and geochemistry of the volcanic rocks in the Nanancun section of the Pu'er area, which provides a new understanding of the evolution of the Paleo-Tethys ocean. The volcanic rock in the area is a rhyolite of plaque-like structure and rhyolite structure. Its phenocrysts are composed of semi-automorphic slab-like K-feldspar and quartz. The matrix is cryptocrystalline feldspar and quartz. The main element analysis showed that the content of SiO2 was 75.59%~77.40%, the content of Al2O3 was 11.69%~12.20%, and the content of K2O (4.13%) was more than Na2O (3.72%), indicating that the rhyolite is Peraluminous high potassium calc-alkaline, calc-alkaline series volcanic rocks. The main elements of CaO/Na2O ratio is 0.01~0.04, Al2O3/(MgO+TFeO) is 0.03~0.06, and CaO/(MgO+TFeO) is 5.51~6.66, The ratio of trace element Nb/Ta is concentrated at 12.27~13.08, with an average of 12.79, and the date of radioactive?isotope 87Sr/86Sr is 0.714~0.719, 207Pb/204Pb is 15.733~15.760, 206Pb/204Pb is 18.903~19.400, indicating that the volcanic source is derived from the remelted (metamorphic) mudstone crust. The standardized trace element distribution curve is irregularly jagged and highly consistent, the date of Rb, Nb, Ta, Y and Yb is rich Rb and low Nb, Ta, Y and Yb, indicate that the volcanic rocks in the southern part of the Langcangjiang have the property of volcanic rocks in the continent marginal arc. The LA-ICP-MS zircon U-Pb chronology shows that the concord age of volcanic rocks is 200.6±2.8Ma, It is consistent with the volcanic rock activity (210-280Ma) in the northern section of the southern Lancangjiang belt, indicating that the volcanic activity in the southern Lancangjiang belt extends at least to the early Jurassic, that is, the subduction activity of the Paleo-Tethys ocean lasts at least to the early Jurassic.
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