辽东古元古代碰撞造山过程的热液铀成矿作用：年代学约束

The Paleo-Proterozoic hydrothermal uranium deposits in Gongchangling- Lianshanguan area are closely related to late Paleo-Proterozoic collision process of the Jiao-Liao-Ji belt. However, the available ages of these uranium deposits show a wide range which confused their formation tectonic settings. To get more accurate ages of these uranium deposits, we plan to take U-Pb, Sm-Nd, EPMA U-Th-Pb isotopic dating on uraninite and step heating 40Ar/39Ar and Rb-Sr isotopic dating on hydrothermal muscovite. These isotopic ages will be compared to the previously published ages related to the rifting-collision evolution of the Jiao-Liao-Ji belt to distinguish which stage of the collison process coincide with the formation of these uranium deposits. This work will improve the understanding to hydrothermal uranium mineralization in collision process, and further contribute to the metallogensis of continental collision.

辽东弓长岭-连山关地区发育的古元古代热液铀矿床与胶-辽-吉带古元古代碰撞造山过程密切相关。已有的铀矿床成矿年龄范围较大，很难明确古元古代热液铀矿床形成的大地构造环境。通过对辽东古元古代典型铀矿床的沥青铀矿开展U-Pb一致线、Sm-Nd等时线、EPMA U-Th-Pb测年，热液蚀变成因白云母开展40Ar/39Ar阶段加热法、Rb-Sr等时线方法的年龄测定，精确厘定古元古代铀成矿的年龄。将铀成矿年龄与胶-辽-吉带古元古代裂谷-闭合造山过程地质事件的年代学数据对比，明确古元古代热液铀成矿事件与碰撞造山过程的关系，深入讨论碰撞造山过程热液铀矿床成矿作用，为进一步丰富大陆碰撞成矿理论提供研究实例。

采用沥青铀矿TIMS U-Pb同位素法、EPMA U-Th-Pb化学法、LA-ICP-MS U-Pb同位素法、Rb-Sr等时线法、Sm-Nd等时线法综合测定连山关铀矿床成矿年龄为~1760Ma；采用沥青铀矿TIMS U-Pb同位素法测定高家沟（405）与BIF伴生沥青铀矿成矿年龄为~1760Ma，翁泉沟硼镁铁矿伴生沥青铀矿、营口六块地含钴黄铁矿伴生沥青油矿、新发现的大石桥组蛇纹石化大理岩中与辉钼矿共/伴生沥青铀矿形成时代均~1800Ma。结合胶-辽-吉造山带研究进展，指出辽东2期（~1800Ma、~1760Ma）区域铀成矿事件形成于胶-辽-吉带碰撞造山带造山后伸展体制降温降压退变质阶段，晚于区域峰期变质作用（1900Ma~1950Ma）、俯冲地体快速折返近等温减压退变质作用（1840 Ma~1870Ma）及相关岩浆活动（1843 Ma~1875Ma）、混合岩化作用（1835 Ma~1870Ma）。研究成果更好的限定了辽东区域铀成矿时代，明确了胶-辽-吉造山带区域铀成矿的动力学背景，为完善碰撞造山成矿理论，尤其是提高碰撞造山带铀成矿理论认识提供了研究实例。