地质学报2017，Vol.91Issue(8)：1743-1759,17.
滇中姚安老街子板内富碱火山岩锆石SHRIMP U-Pb年代学及火山机构划分
Zircon SHRIMP U-Pb Geochronology and Volcanic Edifice Division of the Laojiezi Intraplate Alkali-rich Volcanic Rocks in Yao'an, Central Yunnan Province
摘要
Abstract
The Laojiezi alkali-rich volcano-magmatic complex in Yao'an,Central Yunnan province,is part of the Cenozoic Jinsha River-Ailaoshan alkali-rich intrusive rock zone.It has been widely concerned by the geologists because it hosts a large amount of Pb-Ag-Au polymetallic deposits and is special intraplate tectonic location.Although the previous researchers mainly concentrated on the mineral deposits with main study of metal state and material sources,petrology and geochemistry etc.,there are few studies on the volcanic edifice.This study carried out an investigation over the alkali-rich volcanic rocks in Yao'an using petrography and profile measurement.One complete volcanic edifice is divided:subvolcanic facies (orthophyre contained agglomerates),volcanic-sedimentary facies (tuffaceous conglomerate and sandstone),and volcanic eruption facies.Among them,the volcanic eruption facies are subdivided into the effusion subfacies (ignimbrite and pseudoleucite trachyte) and the explosive subfacies (trachytic ignimbrite contained breccia and agglomerates).Zircon SHRIMP U-Pb dating was also conducted for the Laojiezi rich alkali trachytic tuff and ignimbrite,yielding two 206pb/238U weighted average ages of 33.63±0.50Ma and 33.27±0.38Ma.This indicates that the volcanic eruption age occurred in the Oligocence.The report of this period volcanic rock in the Sanjiang orogenic zone provides not only a new idea for ore prediction in deep and peripheral of the Laojiezi Pb-Ag-Au polymetallic deposit,but also a new window for Cenozoic lithospheric tectonic evolution and the geodynamics process in the southeastern margin of the QinghaiTibet Plateau.关键词
滇中/老街子/富碱火山岩/SHRIMP U-Pb年代学/火山机构Key words
Central Yunnan Province/Laojiezi/alkali-rich volcanic rocks/SHRIMP U-Pb geochronology/volcanic edifice引用本文复制引用
严清高,江小均,吴鹏,孙会一,管申进..滇中姚安老街子板内富碱火山岩锆石SHRIMP U-Pb年代学及火山机构划分[J].地质学报,2017,91(8):1743-1759,17.基金项目
本文为北京离子探针中心开放基金(编号:DDC15-016)、云南省应用基础研究计划青年(编号:2016DF031)和国家重点基础研究发展计划(编号:2015CB452600、2015CB452605)项目联合资助的成果. （编号:DDC15-016）
