ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    陕西勉略宁三角区碧口群火山岩系特征及其地质填图方法探讨

    Characteristics of Volcanic Rock Series from the Bikou Group and New Idea of Geological Mapping in the Mian-Lue-Ning Triangle Area, Shaanxi

    • 摘要: 陕西勉略宁三角区发育中晚元古代碧口群火山岩系,为一套完整火山喷发序列形成的酸-基性火山岩建造。岩石类型以流纹岩、玄武岩及火山碎屑岩为主,夹少量安山岩,该套火山岩由多个火山喷发旋回和韵律组成,岩石普遍变形强烈,发育塑性流变、透入性置换面理和脆韧性剪切带。火山岩系具明显"局部有序,总体无序,应变量大"的特点。通过几年来在该区地质填图实践,以火山旋回-韵律划分识别为基础,根据火山岩性、岩相等物性填图结合火山岩系变形期次和构造样式解析,探索出适合该地区强变形火山岩系填图方法:综合采用"火山岩性+岩相+构造变形样式"有机结合的三重填图方法,在勉略宁地区地质填图中达到了较好的效果,对建立勉略宁三角区构造变形机制、总结碧口群火山岩系成矿规律具有重要意义。

       

      Abstract: The volcanic rock series of the Middle-late Proterozoic Bikou Group is developed in the Mian-Lue-Ning triangle area, Shaanxi Province, which has a complete magmatic eruption sequence of acid-mafic volcanic, containing rhyolite, basalt, pyroclastics and andesite. The volcanic rock series is made of multiple volcanic rhythms with strong deformation, developing with penetrative replacement, foliation plastic flow and ductile shear. This rock series have obvious characteristics of "partial order, total disorder and large variable". Through several years practice of geological mapping in this area, a new idea for geological mapping method for the deformation volcanic rock series has been proposed on the basis of the volcanic cycle-metrical division, the recognition of volcanic lithology, volcanic series deformation and tectonic style. After using the new method of "volcanic lithology, lithofacies and tectonic deformation style", a good result in Mian-Lue-Ning regional geological mapping has been obtained. The new volcanic mapping method will be great significance to reshape the tectonic deformation mechanism and summary metallogenic regularities of the Bikou Group volcanic rock series in the Mian-Lue-Ning triangle area.

       

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