云南兰坪盆地攀天阁组火山岩的Rb-Sr年龄

云南兰坪盆地是三江造山带非常重要的沉积盆地 ,对该盆地的构造属性的认识存在较大的分歧 ,原因之一是对发育在盆地范围内的一套火山岩的形成时代一直没有确切的年龄数据 ,从而造成对火山岩的性质和构造背景认识上的差异。采用 Rb- Sr同位素年代学方法对出露在兰坪盆地剑川马登剖面攀天阁组的流纹岩的年龄进行了研究 ,获得了火山岩的平均年龄为 2 36± 32 Ma的数据 ,结合接触关系和上下地层的时代 ,认为攀天阁组的时代归属为中三叠世 L adinia期

THE AGE OF VOLCANIC ROCK OF THE PANTIANGE FORMATION IN THE LANPING BASIN,YUNNAN PROVINCE

The Lanping basin in Yunnan is a very important sedimentary basin in the Sanjiang Orgenic Belt, but there have been very different opinions on its tectonic attribute. One of the causes in that there have no any data on the exact ages for the forming of the volcanic rocks developed within the basin. Thus many different views were present on the naure and tectonic settings of the volcanic rocks. The rhyolite in the Pantiange Formation exposed in the Madeng Section at Jianchuan of the Lanping basin was dated by the Rb Sr method and the volcanic rocks have produced an average age at 236±32Ma. Combined with the contact relationship and the ages of the overlying and underlying strata, the Pantiange Formation is regarded to be of Middle Trissic (Ladinian Stage) age.