青海省都兰东北部多金属矿床锆石裂变径迹年代学分析

都兰北部地区位于青藏高原北部东昆仑造山带,经历过多次构造事件与热液活动,形成了丰富的矿床资源。本文整合了都兰东北部地区三个多金属矿床锆石裂变径迹定年数据对该区域进行整体分析。将研究区构造活动大致分为210～170 Ma,160～120Ma以及120～100 Ma三个阶段均能体现不同时期的地质事件。210～170 Ma是对羌塘地体与昆仑地体碰撞事件的记录,该时期研究区受热液侵入且开始进入蚀变矿化阶段；160～120 Ma是研究区对碰撞造山结束后进入伸展阶段后大规模隆升事件的响应；120～100 Ma是对拉萨地体与羌塘地体碰撞汇聚的响应。受三期构造事件的影响,都兰东北部地区热液活动一直持续至早中白垩世左右,多期次热液活动使得成矿元素的富集与沉淀,从而形成一定规模的矿床。

Zircon fission track dating evidence in polymetallic ore district, north-eastern Dulan, Qinghai province

The north-eastern Dulan is located in the East Kunlun orogenic belt, northern Qinghai-Tibet plateau. The study area has experienced multiple tectonic events and hydrothermal activities, formed rich mineral resources. This paper applies the zircon fission track date get from three polymetallic deposits in the eastern part of Dulan to analyze the detailed tectonic ages and epochs. They are composed of 3 age groups of 210-170 Ma, 160-120 Ma and 120-100 Ma. These age groups can reveal different tectonic activities. The age group of 210-170 Ma was reflected the collision events between the Qiangtang terrane and the Kunlun terrane, during this period, the study area was invaded by hydrothermal fluid and began to enter the alteration mineralization stage; the 160-120 Ma was response of the study area to the large-scale uplift event after the end of collision orogeny and extension stage; the 120-100 Ma was reflected the converge between the Lhasa terrain and the Qiangtang terrain. The low temperature hydrothermal activity in Dulan area lasted to about Early-Middle Cretaceous influenced by the three-stage tectonic activity. The multi-stage hydrothermal activity enriches and precipitates the ore-forming elements, thus forming large-scale deposits.