江西中生代火山岩

    MESOZOIC VOLCANIC ROCKS IN JIANGXI

    • 摘要: 省内侏罗—白垩系火山岩多以中小型火山盆地产出,岩性变化复杂,特别是南北两地区火山岩组合及成矿专属性的不同,日益引起地质工作者的注视。本文试图通过火山岩岩石化学的研究,以揭示区内火山岩形成时的构造环境,岩浆的发生及其演化。由于水平有限,不妥之处请批评指正。一、地质背景和火山活动特征本地区地处太平洋与欧亚地块交会地带。印支运动是区内地史上一次变革性运动,它结束了区内海侵历史,在运动性质上也由褶皱和凹陷向断裂和隆起演化。燕山运动以明显

       

      Abstract: Jurassic-Cretaceous volcanic rocks in Jiangxi mostly occur as medium- and small-sized volcanic basins.The volcanic activity was obviously controlled by fractures.The volcanic rock associations and metallogenic specialization in southern Jiangxi are utterly different from those in northern Jiangxi as the conditions of the geological structures and behaviour of the magma source in both areas are different.In northern Jiangxi the andesite-dacite-rhyolite association is represented, showing features of reversed succession evolution;while in southern Jiangxi the basalt-dacite-rhyolite association is present, the Changpu cycle showing bimodal features. According to the characteristics of volcanic rocks, it is considered that this volcanic rock series was the product of subduction of the Pacific plate along the Benioff zone towards the Eurasian continent, belonging to active continentalmargin type. The magma was not derived from a single source. It might be derived from the mantle or originate in the continental crust (sial) by anatexis.

       

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