摘要:
选取与漓渚铁矿成矿关系密切的栅溪和广山岩体为研究对象,采用高精度的LA-ICP-MS锆石U-Pb定年方法对栅溪岩体黑云母花岗岩和广山岩体花岗斑岩代表性样品进行了详细的测年工作,在此结果的基础上,结合区域上矿床成矿的时代,讨论了漓渚铁矿的成矿时代。定年结果显示,栅溪岩体的成岩时代为150.1Ma±2.6Ma,而广山岩体经历了多期的岩浆事件,主体成岩时代为147.2Ma±1.7Ma,2个岩体均属于燕山早期岩浆活动的产物。矿区地质特征显示,漓渚铁矿的形成与广山、栅溪岩体成岩期岩浆热液作用关系密切,广山-栅溪岩体的成岩时代即代表了漓渚铁矿矿化的时代,漓渚铁矿矿体主要形成于中侏罗世(约150Ma)。漓渚铁矿成矿时代的精确厘定为邻区寻找同类型矿床指明了方向。
Abstract:
The LA-ICP-MS U-Pb dating of zircons was carried out for two representative rock samples from Guangshan and Zhaxi plutons, which are closely related to mineralization of the Lizhu iron ore deposit. Based on the obtained results and regional chronologic data of mineralization, this paper has dealt with the mineralization age of the Lizhu iron ore deposit. The samples from Zhaxi pluton yielded the age of 150.1±2.6Ma, which is interpreted as its petrogenic age, and the sample from Guangshan pluton shows a number of magmatic events, with the main petrogenic age 147.2±1.7Ma, suggesting that both plutons belong to Yanshannian granitoids. Geological features of the Lizhu iron ore district show that mineralization of the Lizhu iron ore deposit was closely related to the magmatic hydrothermal event of Guangshan and Zhaxi plutons. In other words, the formation age of Guangshan and Zhaxi plutons represents the ore-forming age of the Lizhu iron ore deposit, i.e., Lizhu iron ore bodies were formed in Jurassic (~150Ma). Precise mineralization age of the Lizhu iron ore deposit plays a guiding role in search for the same type of ore deposits in adjacent areas.
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