相山铀矿田成矿后隆升剥露的磷灰石裂变径迹分析

相山铀矿田现今的地貌以典型的低山侵蚀区为特征,侵蚀区的分布规律清楚地表明相山矿田目前仍处于地表侵蚀阶段。7个碎斑熔岩样品的磷灰石裂变径迹年龄为（78.7±7.1）～（34.5±4.1）Ma,高程加权平均年龄61.1Ma,碎斑熔岩在140.3～61.1Ma间,冷却速率7.6℃/Ma;从61.1Ma至现代,冷却速率为1.2℃/Ma,隆升速率为54m/Ma,即新生代以来相山矿田剥蚀了的厚度约3.3km。

A study on fission track of post-ore uplifted and exhumed apatite in Xiangshan uranium ore field

The current landscape of Xiangshan uranium orefield is characterized by the typical eroded low mountain area.The erosion distribution clearly shows that the orefield are still in the stage of surface erosion.Themochronological dating was used to studing the uplift processes of the orefied.Fission track age of apatite from 7 porphyroclastic lava samples are（78.7 ± 7.1）-（34.5 ± 4.1） Ma,the elevation weighted average age 61.1 Ma.Cooling rate of the porphyroclasts lava is 7.6℃/Ma during 140.3-61.1 Ma period,and 1.2℃/Ma,54 m/Ma in 61.1 Ma-modern period.It is inferred that thickness about 3.3 km have been eroded away from the the orefield in Cenozoic.era.