缅甸中央盆地北部新生代隆升的裂变径迹证据
Fission Track Thermochronological Evidence for Cenozoic Uplift of Northern Central Myanmar Basin

缅甸中央盆地北部新生代隆升作用的研究，不仅对全面认识西缅地块的演化具有重要的意义，而且对该地区的油气勘探也具有重要的指导意义.对采自研究区的2个碎屑岩样、1个钻井基底样品进行了磷灰石裂变径迹测年及热历史模拟分析.在弧前钦敦坳陷西缘冲断带、东缘冲起带和西缅岛弧带获得了逐渐变年轻的裂变径迹年龄(分别是70.6±9.3 Ma、53.4±7.5 Ma和22.7±3.0 Ma)，表明缅甸中央盆地北部在空间上存在自西向东的递进变形过程.磷灰石的热历史模拟分析显示，缅甸中央盆地北部自晚白垩世(80±1 Ma)开始，经历了隆升→快速隆升→平稳→缓慢隆升4个阶段.缅甸中央盆地29～20 Ma的快速隆升冷却事件是缅甸北部区域性隆升剥露作用的体现；4 Ma以来缅甸中央盆地缓慢隆升，这一构造事件是印度板块向东挤压碰撞作用的响应.研究表明缅甸中央沉积盆地的空间发育演化与递进式构造变形(隆升)是新特提斯洋/印度洋岩石圈在新生代期间向西缅地块下的多期次俯冲的直接响应.
Study of the Cenozoic uplift of the northern Central Myanmar basin is crucial to better understand both the evolution of the West Burma block and the petroleum exploration in this area. Apatite fission track dating and thermal history modeling were carried out on two detrital samples and one core bedrock sample in this study. Our results show decreasing apatite fission track (AFT) ages in western thrust belt and eastern margin of the Chindwin subbasin to the magmatic arc belt of Myanmar (i.e., 70.6±9.3 Ma, 53.4±7.5 Ma and 22.7±3.0 Ma), indicating a progressive deformation of the northern Central Myanmar basin from west to east. Furthermore, the thermal modeling results indicate that in the Late Cretaceous (80±1 Ma) uplift process of the northern Central Myanmar basin can be divided into four stages: uplifting, rapid uplifting, steady uplifting, and slow uplifting. The rapid uplift and cooling event at the 29-20 Ma represents the regional uplift and exhumation in the northern Central Myanmar basin, followed by the slow uplift of the basin since 4 Ma, which is interpreted as the result of eastward movement and intense collision of the Indian plate with respect to the Asian plate. Our study suggests that the Cenozoic development and progressive deformation of the northern Central Myanmar basin was the direct result of multi-phase subduction of the Neo-Tethyan/Indian lithosphere to the West Burma block