辽东翁泉沟硼矿区二长花岗岩脉锆石U-Pb年龄及对成矿时代的制约

辽东地区翁泉沟硼矿区露天采场产出一条切穿硼矿体的二长花岗岩脉.本研究采集了该二长花岗岩脉的薄片、化学分析样品，并进行锆石LA-ICP-MSU-Pb年代学测试分析.该二长花岗岩脉具有高SiO₂含量，为71.82%~75.68%，较高的Na₂O+K₂O含量，为8.41%~10.57%，属钙碱性-高钾钙碱性系列花岗岩.岩脉中锆石颗粒呈自形柱状，CL图中较黑，因铀含量较高引起.U-Pb上交点年龄为1842±29Ma，其中9个测点得出1842±30Ma的加权平均年龄，反映了该花岗岩脉侵位于古元古代晚期，同时翁泉沟硼镁铁矿成矿应早于该时代.此年龄与前人研究古元古代胶辽吉造山过程中变质作用峰后时间相吻合，反映了古元古代造山作用过程中伴随了硼矿成矿事件.

ZIRCON U-Pb DATING OF MONZOGRANITE DIKES IN WENGQUANGOU BORON OREFIELD,EASTERN LIAONING:Constraints on Metallogenic Age

A monzogranite dike cuts through the ludwigite orebody in the open pit of Wengquangou boron deposit, Liaodong Peninsula. Samples of the dike are collected for thin section and zircon LA-ICP-MS U-Pb geochronology analysis. The monzogranite dike is characterized by high SiO₂ content(71.82%-75.68%) and high Na₂O+K₂O content (8.41%-10.57%), belonging to calc alkali-high K calc alkaline series granite. The zircon grains in the dikes are euhedral column in shape and dark in the CL image due to the high uranium content. The U-Pb upper intercept age is 1842±29 Ma, among which 9 testing points yield the weighted average age of 1842±30 Ma, indicating that the emplacement age of dike was Late Paleoproterozoic and the Wengquangou ludwigite deposit should be formed earlier. The age is consistent with the post-peak time of metamorphism in the Paleoproterozoic Jiao-Liao-Ji orogeny, reflecting the boron mineralization occurred during the process.