内蒙古大青山晚中生代以来的隆升--剥露过程

Uplift-Exhumation History of Daqing Mountain, Inner Mongolia Since Late Mesozoic

对大青山东段4件基岩样品进行磷灰石裂变径迹研究,获得该区晚中生代以来的隆升?剥露历史,并探讨大青山现代地貌的形成。样品的磷灰石裂变径迹年龄为57.7±3.8~50.4±3.3 Ma,封闭径迹长度分布在10.7±0.4~9.9±0.1μm之间。热历史模拟结果表明,大青山地区存在晚白垩世(约100~90 Ma)和中?晚中新世(13.5~7 Ma)以来两个快速抬升冷却阶段,13.5~7 Ma以来是本区剥露最快的时期,这一阶段的隆升造就现今大青山的地貌格局。

Four bedrock samples,collected from the eastern segment of Daqing Mountain,were analyzed usingapatite fission-track(AFT)method.This elucidates the uplift-exhumation history of this area since the LateCretaceous-in particular,when the present geomorphology of Daqing Mountain was shaped.The AFT agesrange from57.7±3.8Ma to50.4±3.3Ma and the track length is between10.7±0.4μm and9.9±0.1μm.Modeling ofthe fission track data suggests two stages of rapid uplift and cooling,100?90Ma and since13.5?7Ma.The secondcooling stage(since13.5?7Ma)was characterized by the fast uplift-exhumation in this area,resulting in thepresent geomorphology of Daqing Mountain.