磷灰石裂变径迹法研究阿尔泰青河地区地质热历史

Apatite fission track dating and thermal history of Qing-He Region in Altay Mountains

对阿尔泰青河县城附近的闪长岩岩体进行了磷灰石裂变径迹研究,并探讨了该区的地质热历史。裂变径迹年龄为(78±5)—(95±5)Ma,平均径迹长度为(13.2±1.2)—(13.5±1.3)μm。热历史模拟结果表明,阿尔泰青河地区具有4阶段的热演化模式,其中115—85Ma的快速冷却阶段反映了该地区在燕山期仍然存在着岩浆侵入活动和断裂带构造运动。

Fission track ages （FTA） and track lengths of apatite from Qing-He diorite intrusion in Altay Mountains are measured. Apatite fission track ages of three diorite samples is range from （78 ± 5） Ma to （95 ± 5） Ma, and the lengths of horizontal confined spontaneous fission tracks are （13.2 ± 1.2）-（13.5 ± 1.3） pm. The distribution of the track length is narrow and symmetrical with a mean length of approximately 13.3 pm and a standard deviation of around 0.1μm. The inverse modeling results show that thermal history of this region has four stages, two rapid uplift stages and two stable ones. The rapid uplift during the 115-85 Ma with the cooling rate of 2.2 ℃/Ma suggests that this region still existed magmatic intrusion and tectonic movements in Yanshanian.