摘要
磷灰石微区原位LA-ICP-MS U-Pb同位素定年研究是一个新的测年研究领域和趋势。东昆仑东段那更矿区含矿石英脉中磷灰石表面均匀明亮,具有典型的未蚀变岩浆磷灰石特征,表明并未受流体的影响。磷灰石微区原位U-Pb测年结果显示,石英脉中磷灰石下交点年龄分别为409.0 Ma±3.7 Ma及376.2 Ma±5.6 Ma,与各自的^(207)Pb校正年龄非常吻合,精确度高,代表两期磷灰石矿物的形成年龄。其中,409 Ma的磷灰石年龄与区域上早泥盆世东昆仑造山带碰撞后伸展阶段岩浆活动大爆发相符,而376 Ma的岩浆磷灰石年龄目前在东昆仑东段地区发现尚属首次,推测是东昆仑造山带志留纪—泥盆纪这一期幔源岩浆活动大爆发末期的产物。本次工作获得的409 Ma和376 Ma的岩浆磷灰石年龄证实了那更矿区深部存在泥盆纪构造岩浆活动,为区域构造演化研究提供了新证据。
Surface of apatite from ore-bearing quartz vein in Nageng property in the east Kunlun mountains is uniform and looks bright.This is characteristic of the fresh apatite,i.e.the apatite is not influenced by hydrothermal fluid.Micro-area in situ LA-ICP-MS U-Pb isotopic age dating of the apatite shows that the lower intersection age is 409.0 Ma±3.7 Ma and 376.2 Ma±5.6 Ma respectively,exellently coincided with their ^(207)Pb correction age,very accurate representing the formation age of apatite of two stages.409 Ma,the age of apatite is accorded with the regional Early Devonian magmatic out break in the post-collision extension stage of the east Kunlun orogenic belt.376 Ma,the age is firstly obtained in the east part of east Kunlun mountsins and is presumed to be product of late Silurian-Devonian mantle-decided magmatic outbreak.The two ages obtained in this work imply that deep tectonic-magmatic activity took place in Nageng property during Devonian Period and pride new evidence for study on regional tectonic evolution.
作者
陈静
CHEN Jing(Qinghai Provincial Key Lab of Physical Geography and Environmental Process,College of Geographic Science,Qinghai Normal University,Xining 810000,Qinghai Province,China)
出处
《地质找矿论丛》
CAS
2024年第4期519-525,共7页
Contributions to Geology and Mineral Resources Research
基金
2023年度青海省“昆仑英才·高端创新创业人才”项目(青人才字[2024]号)。
关键词
东昆仑
那更地区
磷灰石
U-PB年龄
地质意义
east Kunlun mountains
Nageng area
apatite
U-Pb dating
geological significance