吉林辽源西保安群花岗质糜棱岩SHRIMP U-Pb定年

吉林辽源西保安群是大面积花岗岩侵入体中的残留的构造岩片，传统认为属于华力西晚期或中侏罗世花岗闪长岩-二长花岗岩系。本文通过对接触界线附近花岗质糜棱岩样品采集和锆石SHRIMP U-Pb定年，获得多组锆石年龄值为236~231Ma、267.6~358.6Ma、416.3±6.8Ma、956±16Ma。认为该区花岗岩的侵入期次相当复杂，发育有早中三叠世岩体和发生了中、晚华力西期岩浆活动，西拉木伦河碰撞带可以东延至此，残留锆石的年龄与加里东期和Rodinia期拼合的构造岩浆活动相对应。

SHRIMP U-Pb dating on granitic mylonite for Liaoyuan Xibaoan Group

Xibaoan Group in Jilin Province is a series of the tectonic slices residuesed in the granite intrusions, which is traditionally considered to be Late Variscan or Middle Jurassic granodiorite-monzonitic granite. In this study, samples of the granitic mylonite were collected along the contact line of Xibaoan Group in Dongfeng County Jilin Province, and the zircons were dated using the U-Pb method. The results indicate several zircon ages: 236~231Ma, 267.6~358.6Ma, 416.3±6.8Ma, and 956±16Ma. Based on the regional geology, we arrived at the following conclusions: (1) The intrusive monzonitic granite of the Xibaoan Group in the contact zone experienced ductile shear deformation and formed in the Early-Middle Triassic. This event was an important part of the eastern extension of the collision belt of the Xar Moron River. (2) The zircon U-Pb SHRIMP age dates indicate that there were multiple periods of emplacement and multiple periods of development of residual magmatic zircons. The tectonic evolution of the Xibaoan Group was complex. (3) The U-Pb SHRIMP age dating of the residual zircons suggest that the magmatic activity occurred during the Caledonian and during the flattening of the Rodinia supercontinent.