郝士龙, 李成禄, 丁继双, 于援帮, 赵焕利, 李博文. 2021: 黑龙江多宝山地区中侏罗世火山岩的发现及其对蒙古-鄂霍茨克洋闭合范围的限定. 地质通报, 40(10): 1757-1772.
    引用本文: 郝士龙, 李成禄, 丁继双, 于援帮, 赵焕利, 李博文. 2021: 黑龙江多宝山地区中侏罗世火山岩的发现及其对蒙古-鄂霍茨克洋闭合范围的限定. 地质通报, 40(10): 1757-1772.
    HAO Shilong, LI Chenglu, DING Jishuang, YU Yuanbang, ZHAO Huanli, LI Bowen. 2021: Discovery of Middle Jurassic volcanic rocks in the Duobaoshan area of Heilongjiang Province and constraints on the influence area of the Mongolian-Okhotsk Ocean closure. Geological Bulletin of China, 40(10): 1757-1772.
    Citation: HAO Shilong, LI Chenglu, DING Jishuang, YU Yuanbang, ZHAO Huanli, LI Bowen. 2021: Discovery of Middle Jurassic volcanic rocks in the Duobaoshan area of Heilongjiang Province and constraints on the influence area of the Mongolian-Okhotsk Ocean closure. Geological Bulletin of China, 40(10): 1757-1772.

    黑龙江多宝山地区中侏罗世火山岩的发现及其对蒙古-鄂霍茨克洋闭合范围的限定

    Discovery of Middle Jurassic volcanic rocks in the Duobaoshan area of Heilongjiang Province and constraints on the influence area of the Mongolian-Okhotsk Ocean closure

    • 摘要: 黑龙江省多宝山地区位于中亚造山带东段、兴安地块东南缘,发育大面积早—中侏罗世侵入岩,但至今未发现同时代的火山岩。在多宝山地区首次发现了同时期的火山岩,并确定为一套英安岩、流纹岩和粗面岩组合。为进一步明确其形成时代及反映的构造意义,对出露的火山岩开展了锆石U-Pb测年和岩石地球化学分析。锆石U-Pb年龄显示,火山岩形成时代为167.1~169.3 Ma,为中侏罗世喷发成岩。火山岩具有富碱(Na2O+K2O=3.70%~7.66%)、富铝(Al2O3=11.42%~19.00%)的特征,属于高钾钙碱性、过铝质(A/CNK=1.08~3.73)岩石。稀土元素呈轻稀土元素富集、重稀土元素亏损的右倾特征,具负Eu异常(δEu=0.53~0.79)。微量元素显示富集Rb、Ba、K、Th、U、Pb,亏损Nb、Ta、Ti、P、Sr。总体显示,该中侏罗世火山岩起源于新生陆壳物质的部分熔融。根据Ta-Yb、Nb-Y构造环境判别图解,该期火山岩形成于挤压背景环境。结合区域构造背景及其演化特征,综合认为,中侏罗世火山岩应是蒙古-鄂霍茨克洋闭合过程导致的陆-陆碰撞作用的产物。闭合导致的陆陆碰撞作用已影响到兴安地块东南缘。

       

      Abstract: The Duobaoshan area of Heilongjiang Province is located in the eastern part of the Central Asian Orogenic Belt and the southeastern margin of the Xing'an Block, where large areas of Early-Middle Jurassic intrusive rocks are developed, but no contemporaneous volcanic rock has been reported there. During the exploration of gold deposits in the Duobaoshan area, volcanic rocks of the same period were discovered for the first time and they were identified as a suit of dacite, rhyolite, and trachyte. Zircon U-Pb dating and petrogeochemical analyses were carried out on these volcanic rocks to further clarify their formation age and tectonic significance. The U-Pb dating of zircons from the volcanic rocks yielded ages of 167.1~169.3 Ma, indicating that these rocks erupted during Middle Jurassic. The petrogeochemical analysis shows that the volcanic rocks are characterized by high alkali (Na2O+ K2O=3.70%~7.66%) and aluminum (Al2O3=11.42%~19.00%), and are peraluminous (A/CNK=1.08~3.73) with high potassium calcium alkali. The rare earth elements are characterized by the enrichment of light rare earth elements and right-leaning of heavy rare earth elements depletion, with slightly negative Eu anomalies (δEu=0.53~0.79).Trace elements are enriched in Rb, Ba, K, Th, U and Pb, and depleted in Nb, Ta, Ti, P and Sr.It is generally shown that the Mid-Jurassic volcanic rocks were derived from the partial melting of newly continental crust material. The discriminant diagrams of Ta-Yb and Nb-Y indicates that the Middle Jurassic volcanic rocks were formed in the compressional background. Combined with the regional tectonic setting and evolution characteristics, it is concluded that the Middle Jurassic volcanic rocks should be the product of the continent-continent collision caused by Mongolian-Okhotsk Ocean closure.Indicatively, the collision affected the southeastern margin of the Xing'an Block.

       

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