针对沉积岩容矿铅锌矿床的定年难题,选用闪锌矿的Rb-Sr法和成矿阶段方解石的Sm-Nd法,对白秧坪铅锌铜银多金属矿床3个矿段(吴底厂、李子坪、富隆厂)分别测定,取得了较好的定年效果.测得白秧坪铅锌多金属矿床的铅锌成矿年龄为30 ～ 29Ma,而且3个矿段结果可互相印证.进而通过成矿年龄的探讨,认为矿区发生过2次矿化事件,一期为以铜为主的矿化,发生于古新世末-始新世初期,印度板块-欧亚板块强烈挤压后的应力松弛阶段成矿；另一期是以铅锌为主的矿化,发生于30～29 Ma,对应于始新世末-渐新世早期挤压后应力松弛阶段.两期矿化事件在上千千米的“三江”成矿带上普遍存在,但在不同部位铅锌成矿时代略有不同,印度板块的东北角首先对接欧亚板决,位于岬角处正碰位置铅锌成矿要稍早于两侧的铅锌矿化事件.%Baiyangping lead-zinc-copper-silver polymetallic deposit is a low-to-moderate temperature sediment-hosted hydrothermal deposit, located in northern Lanping basin, Yunnan Province. In this paper, we get the isochronal age between 30Ma and 29Ma for deposit using the Rb-Sr dating of sphalerite and Sm-Nd dating of mineralization stage calcite. By discussing the age of mineralization, it can be concluded that there are twice mineralization events in mining area, one for the main copper mineralization occurred between Late Paleocene and Early Eocene, according with the short-term stress relaxation stage after strong compression of Indian plate and Eurasia plate; another was main lead and zinc polymetallic mineralization between 30Ma and 29Ma, corresponding to the Late Eocene-Early Oligocene stress relaxation stage after compression. In the Sanjiang area, the twice mineralization events also exist in thousands of miles mineralization belt, but the lead-zinc mineralization ages were different in different parts of the Sanjiang area. The northeast corner of Indian plate was the first docking Eurasian plate, so the ages of deposits located on collisions area at first was earlier than the ages of other lead-zinc mineralization events in Sanjiang area.
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