徐云飞, 刘军平, 丛峰, 孙柏东, 黄晓明. 滇西澜沧江南段小湾地区崇山岩群LA-ICP-MS锆石U-Pb年龄及其地质意义[J]. 地质通报, 2018, 37(6): 1006-1014.
    引用本文: 徐云飞, 刘军平, 丛峰, 孙柏东, 黄晓明. 滇西澜沧江南段小湾地区崇山岩群LA-ICP-MS锆石U-Pb年龄及其地质意义[J]. 地质通报, 2018, 37(6): 1006-1014.
    XU Yunfei, LIU Junping, CONG Feng, SUN Baidong, HUANG Xiaoming. LA-ICP-MS zircon U-Pb dating of the Chongshan Group in the Xiaowan area along the southern section of the Lancang River in western Yunnan and its geological significance[J]. Geological Bulletin of China, 2018, 37(6): 1006-1014.
    Citation: XU Yunfei, LIU Junping, CONG Feng, SUN Baidong, HUANG Xiaoming. LA-ICP-MS zircon U-Pb dating of the Chongshan Group in the Xiaowan area along the southern section of the Lancang River in western Yunnan and its geological significance[J]. Geological Bulletin of China, 2018, 37(6): 1006-1014.

    滇西澜沧江南段小湾地区崇山岩群LA-ICP-MS锆石U-Pb年龄及其地质意义

    LA-ICP-MS zircon U-Pb dating of the Chongshan Group in the Xiaowan area along the southern section of the Lancang River in western Yunnan and its geological significance

    • 摘要: 滇西崇山岩群一直被认为是元古宙的大陆地壳-结晶基底,但至今无精确的年龄依据。对滇西澜沧江南段小湾地区崇山岩群的5件样品(糜棱岩化斜长变粒岩、黑云斜长角闪岩、片麻岩、糜棱岩化花岗质片麻岩、糜棱岩化黑云斜长变粒岩)进行锆石U-Pb定年。5件样品的锆石阴极发光图像显示,锆石有明显的生长振荡环带,指示岩浆成因。5件样品锆石的206Pb/238U年龄加权平均值分别为239.4±3.8Ma、248.4±4.3Ma、237.1±5.7Ma、268.7±3.2Ma、238.4±5.5Ma。根据野外地质特征和年龄数据,认为滇西澜沧江南段小湾地区崇山岩群是不同时代、不同岩性的岩体/地层(二叠系、三叠系)经后期变质作用形成的一套正变质岩,并不全是古老基底岩石出露。

       

      Abstract: This paper focuses on the LA-ICP-MS U-Pb ages of the zircons of five samples(mylonitization plagioclase leptynite, bio-tite amphibolites, gneiss, mylonitization granitic gneiss, and mylonitization biotite amphibolites)from the Chongshan Group in the Xiaowan area along the southern section of Lancang River of western Yunnan.Cathodoluminescence images of five samples reveal that these zircon crystals generally have oscillatory zoning, implying their magatic genesis.One hundred and two analyses of five sam-ples yielded concordance, with their weighted average ages being 239.4±3.8Ma, 248.4±4.3Ma, 237.1±5.7Ma, 268.7±3.2Ma, and 238.4±5.5Ma.According to geological characteristics and available age data, it is considered that the so-called Chongshan Group in the Xiaowan area is orthometamorphite composed of various parent components with different ages rather than entirely Proterozoic crystalline basement rocks as previously considered.

       

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