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云南蒙自白牛厂多金属矿床位于个旧与都龙矿床之间,由于缺少年代学数据,多种成因观点相持不下。利用锡石原位LA-MC-ICP-MS U-Pb法对采自沉积作用最为显著的白羊矿段的两个锡石样品进行年代学研究,得出238U/207Pb-206Pb/207Pb等时线年龄分别为(87.4±3.7)Ma(MSWD=9.0)和(88.4±4.3)Ma(MSWD=9.9),与薄竹山花岗岩锆石U-Pb年龄(84.1±2.6～87.83±0.39)Ma在误差范围内一致,说明锡的成矿与岩浆作用关系密切。结合南岭地区其他锡多金属矿床锡石TIMS U-Pb年代学研究,锡石U-Pb定年在锡多金属矿床直接定年中具有很大优势,而原位LA-MC-ICP-MS U-Pb法定年在该类型矿床的年代学研究中更是开辟了一条新途径。由于锡石普通铅含量较高,在校正过程中会影响数据可靠性,因此该方法需进一步完善,以满足精确定年的需要。
The Yunnan Mengzi White Cattle Polymetallic Deposit is located between Gejiu and Dulong Deposits. Due to the lack of geochronology data, the viewpoints of many causes can not be sustained. Two cassiterite samples from the Aries deposit with the most obvious sedimentation were analyzed by in-situ LA-MC-ICP-MS U-Pb dating of Cassiterite, and the 238U / 207Pb-206Pb / 207Pb isochron (87.4 ± 3.7) Ma (MSWD = 9.0) and (88.4 ± 4.3) Ma (MSWD = 9.9), respectively, and were similar to the U-Pb ages of the Cezhushan granites (84.1 ± 2.6 ~ 87.83 ± 0.39) Ma in the error range Within the same, indicating that tin mineralization and magmatism are closely related. Based on the TIMS U-Pb chronology of cassiterite from other tin polymetallic deposits in Nanling, the U-Pb dating of cassiterite is of great advantage in the direct dating of tin polymetallic deposits. In situ LA-MC-ICP-MS U- Pb dating has opened up a new way in the chronology study of this type of deposit. Due to the high normal lead content of cassiterite, data reliability will be affected during the calibration process, so this method needs to be further improved to meet the needs of precise dating.