北喜马拉雅带构造活动的裂变径迹定年证据

Fission track dating evidence on tectonic activities of northern Himalaya block

从浪卡子至雅鲁藏布江逆冲带剖面中获得的 4个磷灰石裂变径迹年龄为 13.6— 17.2Ma ,记录了区内陆 -陆碰撞的时代 ,而这恰恰有别于前人的资料。磷灰石裂变径迹年龄与样品高程呈负相关关系 ,表明陆 -陆碰撞伴随有快速的抬升 ,其抬升速率为 176m/Ma。 13.6Ma以来的剥蚀量约为 2 .9km ,冷却速率和剥蚀速率分别约为 7℃ /Ma和 2 13m/Ma。 3个锆石裂变径迹年龄值相差较大 ,χ2 检验值约为 0 .1%,证实该区陆内造山作用是在低温状态下进行的。

Fission track ages (FTA) of 4 apatite samples collected from Langkazi to Yarlung Zangbo thrust zone range between 13.6 and 17.2 Ma, reflecting the time of continent-continent collision and differing from previous data. The negative correlation between the FTA and sample elevations shows there was rapid uplifting during the continent-continent collision with uplifting rate of 176m/Ma. Denudation degree, denudation rate and cooling rate were ~2.9km, 213m/Ma and 7℃/Ma respectively since 13.6Ma. FTA of 3 zircon samples are different significantly and have χ 2 test value of <0.1%, confirming the orogeny within continent went under low temperature.