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    西准噶尔萨吾尔地区二叠纪火山活动规律

    Permian volcanism in the Sawu’er area, western Junggar

    • 摘要: 提要:西准噶尔萨吾尔地区位于新疆阿勒泰的吉木乃县及塔城地区和丰县。区内泥盆纪—二叠纪均有火山活动,其中二叠纪火山作用尤为强烈。二叠纪火山岩地层包括哈尔加乌组和卡拉岗组,哈尔加乌组为一套陆相中基性-中性火山岩及火山碎屑岩,卡拉岗组为一套陆相中基性-中酸性火山岩及火山碎屑岩。哈尔加乌—卡拉岗旋回火山岩主要岩性包括橄榄玄武岩、玄武岩、粗玄岩、安山岩、粗安岩、流纹岩、火山碎屑岩等。根据火山岩地层综合剖面以及火山岩的岩石学、岩相学特征,萨吾尔地区二叠纪火山活动由早至晚可分为5个阶段:中性喷发阶段、间歇性基性喷发阶段、酸性爆发及喷溢阶段、小规模中性间歇性爆发及喷溢阶段、基性喷发阶段;火山岩为陆相火山岩,具有双峰式特征,形成于伸展的构造背景下。

       

      Abstract: Abstract:The Sawu’er area in western Junggar is located in Jeminay County of the Altay region and Hefeng County of the Tacheng region, Xinjiang. Volcanism occurred in the area during the Middle Devonian to Early Permian, and it was particularly strong in the Permian. Permian volcanic rocks include the Ha'erjiawu Formation and Kalagang Formation. The Ha'erjiawu Formation consists of a suite of intermediate-basic and intermediate continental volcanic rocks and pyroclastic rocks, and the Kalagang Formation consists of a suite of intermediate-basic and intermediate-acid volcanic rocks and pyroclastic rocks. The volcanic rocks of the Ha'erjiawu-Kalagang cycle include olivine basalt, basalt, trachybasalt, andesite, trachyandesite, rhyolite and pyroclastic rocks. According to the composite stratigraphic section of volcanic rocks and lithological and petrographic characteristics of volcanic rocks, the Permian volcanism in the Sawu’er area occurred in five phases;they are from early to late as follows:the intermediate volcanic eruption phase, intermittent basic volcanic eruption phase, acid volcanic eruption phase, small-scale intermittent intermediate volcanic exploration phase and basic volcanic outpouring phase. The Permian volcanic rocks are continental ones and have the characteristics of typical bimodal volcanic rocks. They formed in an extensional setting.

       

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