大兴安岭东南坡新生代隆升及地貌演化的裂变径迹研究

Uplift and Topography Evolution Research at FT in Cenozoic of South-Eastern Slope of Daxing'anling Mountains

通过磷灰石裂变径迹热年代学研究,揭示了新生代时期大兴安岭东南坡平均隆升速率为29.68m/Ma,大约隆升了1 944 m,平均降温103.50℃,平均地温梯度为53.24℃/km。在时间上,其隆升剥蚀具有明显的幕式特点,5次低速和4次高速隆升相间分布。其中,4个高速隆升期分别是距今56.44-49.65Ma、40.40-31.80 Ma2、5.00-17.91 Ma1、1.72-4.45 Ma。在空间上,隆升存在差异,根据其隆升剥蚀情况,可将新生代大兴安岭东南坡的地貌演化分为4个阶段：（1）距今65.50-56.44 Ma为以FT4为分隔点的定点分隔型地貌;（2）56.44-40.40 Ma为挠曲下降型地貌;（3）40.40-8.00 Ma为以FT1为分隔点的定点分隔型地貌;（4）8.00-0.00 Ma为以FT7为分隔点的定点分隔型地貌。在总体隆升的高速期,地貌类型发生转换。

According to AFT thermal chronology,the research shows the uplift rate is 29.68 m/Ma,the uplift quantity is 1 944 m,the average reduced temperature is 103.5 ℃,the average gradient of ground temperature is 53.24 ℃/km in Cenozoic of south-eastern slope of Daxing＇anling Mountains.In the domain of time,uplift of south-eastern slope of Daxing＇anling reveals its act character;its velocity shows 5 lowliness and 4 highnesses.And 4 highnesses are 56.44-49.65 Ma,40.40-31.80 Ma,25.00-17.91 Ma,11.72-4.45 Ma.In the domain of space,the uplift-denudation and topgraphy evolution showed 4 phases.The first phase is pinned divide model whose pin is at FT4 point in 65.50-56.44 Ma.The second phase is downwarp model in 56.44-40.40 Ma.The third phase is pinned divide model whose pin is at FT1 point in 40.40-8.00 Ma.The fourth phase is pinned divide model whose pin is at FT7 point in 8.00-0.00 Ma.The types of topography transformed during the high speed period of the whole uplift.