CHARACTERISTICS OF RECENT EJECTA OFTHE CHANGBAISHAN TIANCHI VOLCANO,CHINA
CHARACTERISTICS OF RECENT EJECTA OFTHE CHANGBAISHAN TIANCHI VOLCANO,CHINA
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发表时间：
2006
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通讯作者：
Yang Qing-fu
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作者：
Yang Qing-fu
位于中朝边境的长白山天池火山（42° N，128° E）是我国最危险的一座火山，具有很高的破坏性喷发潜力。在开展长白山天池火山近代喷发历史的研究中,通过野外考察、粒度分析、岩石化学研究,识别出了一套新的火山喷发物。新的喷出物是在天池东北侧发现的。这是一套多层火山碎屑沉积物，厚9.2m，覆盖在1668年的空气沉降存款上。粒度分析表明，喷出物主要由瀑布存款和涌涌存款物组成，喷发类型为热液岩浆喷发。涌浪存款的分维值为2.7113，而秋季沉积物的分维值在2.3028 ~ 2.4627之间，平均值为2.36。显微镜下观察到骨架玻璃碎片，未发现粘土矿物，为爆炸喷发形成的原生存款。浮石成分的岩石化学分析表明，该岩浆为粗面质岩浆。根据历史记载、地层对比和矿床特征，推测其为1903年火山喷发的产物。
The Changbaishan Tianchi volcano on the border between China and North Korea (42° N,128° E) is the most dangerous one with high destructive eruption potential in China. In the research of recent eruption history of the Tianchi volcano, a set of recent ejecta were recognized through field investigation, grain size analysis and petrochemistry analysis. The new ejecta were found on the northeast side of the Tianchi Lake. It is a set of multi-layered pyroclastic deposits of 9.2m thick overlying the 1668 AD airfall deposit. Grain size analysis shows that the ejecta are composed mainly of fall deposit with an interbed of surge deposit, and the type of eruption is phreatomagmatic. Fractal dimension value of the surge deposit is 2.7113, while that of the fall deposits ranges from 2.3028 to 2.4627, having an average value of 2.36. In the microscope, skeleton vitric fragments are observed but clay mineral is not found in the deposits, indicating that they are primary deposit produced by explosive eruption. Petrochemistry analysis of pumice component indicates that the magma can be assigned to trachytic magma. Based on historical records, stratigraphic correlation and features of the deposits, it is estimated that the ejecta are the product of 1903 AD eruption.