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引用本文:吕留彦,李静,曾文涛,俞赛赢,孙载波,王晓峰. 滇西南南澜沧江构造岩浆岩带早侏罗世火山岩的发现——兼论云南省境内印支构造旋回的上限[J]. 中国地质, 2019, 46(6): 1270-1283.
Lü Liuyan,LI Jing,ZENG Wentao,YU Saiying,SUN Zaibo,WANG Xiaofeng. The discovery of Early Jurassic volcanic rocks along the Southern Lancangjiang tectonic magmatic belt in southwest Yunnan, with a discussion on the upper limit of Indosinian tectonic cycles in Yunnan Province[J]. Geology in China, 2019, 46(6): 1270-1283(in Chinese with English abstract).
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滇西南南澜沧江构造岩浆岩带早侏罗世火山岩的发现——兼论云南省境内印支构造旋回的上限
吕留彦1,2, 李静1,3, 曾文涛3, 俞赛赢3, 孙载波3, 王晓峰3
1.昆明理工大学国土资源工程学院, 云南 昆明 650093;2.贵州省地质调查院, 贵州 贵阳 550081;3.云南省地质调查院, 云南 昆明 650216
摘要:
采用锆石激光剥蚀法(LA-ICP-MS)对滇西南南澜沧江火山岩带普洱市江桥—那澜一带的流纹岩进行了年代测定,获得了(196.7±2.3)Ma、(198.1±3.5)Ma的同位素年龄;表明该地区的流纹岩形成于早侏罗世,而非前人划分的晚三叠世,填补了该地区早侏罗世的火山-沉积记录。从岩石的主元素、稀土元素及微量元素资料分析,南澜沧江构造岩浆岩带早侏罗世的火山岩形成于碰撞后的伸展构造背景,可能与西侧昌宁—孟连古特提斯洋盆关闭后,俯冲岩石圈板片或造山带山根的拆沉作用相关,属后碰撞—后造山阶段岩浆活动的产物。具有典型后造山花岗岩或“A”型花岗岩的特征,其指示了印支构造旋回在滇西南地区最终结束的时间上限。
关键词:  滇西  南澜沧江带  流纹岩  U-Pb年龄  地球化学  构造环境
DOI:10.12029/gc20190603
分类号:P542
基金项目:中国地质调查局项目(1212011120593、1212011120595)资助。
The discovery of Early Jurassic volcanic rocks along the Southern Lancangjiang tectonic magmatic belt in southwest Yunnan, with a discussion on the upper limit of Indosinian tectonic cycles in Yunnan Province
Lü Liuyan1,2, LI Jing1,3, ZENG Wentao3, YU Saiying3, SUN Zaibo3, WANG Xiaofeng3
1.Kunming University of Science and Technology, Kunming 650093, Yunnan, China;2.Guizhou Institute of Geological Survey, Guiyang 550081, Guizhou, China;3.Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China
Abstract:
The ages of rhyodacite in Jiangqiao-Nalan area of Pu'er City was determined by utilization of zircon-LA-ICP-MS in south Lancangjiang zone, and the result of U-Pb dating yielded (196.7±2.3)Ma and (198.1±3.5)Ma, which indicates that rhyolite in this area was formed in early Jurassic instead of in Late Triassic. The data fill in the record of volcanic-sedimentary activity in Jurassic's geological history. The analysis of the major elements, REE and trace elements of rocks shows that the volcanic rocks of lower Jurassic in South Lancangjiang zone were formed under the extensional tectonic background after collision, and were probably related to the subducted lithosphere plates or orogenic belt of Yamane delamination, and that they occurred after the closure of lower Cretaceous in this area were typically associated with the POG (post-orogenic granite) or A2 granite. These data constrain the final time of Indosinian cycle. The granite has the feature of post-orogenic granite or "A" type granite, and it indicates the termination time of Indo-Chinese cycle in southwestern Yunnan.
Key words:  southwestern Yunnan  South Lancangjiang zone  rhyolite  U-Pb age  geochemistry  tectonic environment  geological survey engineering