摘要:
本区泥盆系主要为一套碳酸盐岩沉积物,以白云岩为主。其形成机理以混合水白云石化作用为主。以白云岩镜下结构为飘浮菱面体结构、接触菱面体结构、直边镶嵌结构及缝合镶嵌结构。阴极发光和电子探针分析结果表明:混合云化形成的白云石从中心到边缘,Fe++、Mn++富集,K+贫化,形成白云石雾心亮边的特点,阴极发光则表现为具核心和环带。在地下成岩及深埋环境中,巨晶白云石在单偏光下具褐色环带,阴极发光下因富铁而呈黑红色—不发光。
Abstract:
The; Devonian in Ninglang- Lijiang region of western Chuxiong Basin, Yunnan, is dommanted by a series of carbonate sediments. The dolomitic rocks is one of the major rock types and has largely a forming mechanism of mixed dolomitization. Under microscopy, the fabrics of dolomitic rocks are floating-romb, contact- romb, hypidiotopic mosaic and sutured mosaic fabrics. It is suggested with the results of cathodoluminescence and electronic probe analysis that: the dolomite formed through mixed dolomitization has a tendancey of Fe++, Mn++becoming rich but K+poor fron center to margin. Dolomite grains are characterized by fogged center with clear margin, which display nuclei and girdles under cathodoluminescence microscopy. The very coarsely crystalline dolomite in subsruface and deep burial diagenesis environments display brown girdles under microscopy but lumines dark- red to non- luminescence under .cathodoluminescence microscopy.
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