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报道囊谦盆地新生代火山岩 9个样品的K Ar同位素稀释法定年的结果 .全岩或单矿物黑云母的表面年龄均在 32 .0 4～ 36 .5 0Ma的范围之中 .放射成因Ar与K构成了相关性良好的一条等时线 ,表明样品中既无过剩Ar,也没有放射成因Ar的丢失 ,即上述年龄值为真实的成岩年龄 .印度板块与欧亚板块的碰撞发生在 45～ 5 0Ma之前 .本区火山活动是处在碰撞后构造环境 ,受岩石圈剧烈增厚和强烈的陆内剪切 走滑断裂带的控制 ,有证据表明 ,高原东、西、北部岩浆活动的时代存在着差异 .脉动式的岩浆侵入和喷发是高原阶段性隆升的示踪剂
The results of K Ar isotope dilution dating of nine samples from the Cenozoic volcanic rocks in the Xunqian Basin are reported.The surface ages of the whole rock or single mineral biotite range from 32.04 to 36.05 Ma.The radiogenic Ar and K constitutes a good correlation of an isochronal line, indicating that there is neither excessive Ar nor the radiogenic arginine loss in the sample, ie, the age above is the true diagenetic age.The collision between the Indian plate and Eurasian plate occurs at 45 ~ Before 5Ma, the volcanic activity in this area was controlled by the post-collision tectonic setting, under the severe thickened lithosphere and intensive intracontinental shear-strike-slip fault zone. There is evidence that the age of magmatic activities in the east, west and north of the plateau There is a difference between them: pulsatile magmatic intrusions and eruptions are tracers of plateau uplift