基于MELTS模型的长白山天池火山岩浆演化过程的新认识  

NEW UNDERSTANDING OF THE MAGMA EVOLUTION OF CHANGBAISHAN-TIANCHI VOLCANO BASED ON MELTS SIMULATION

作　　者：周秉锐 潘波[1,2] 尹成孝 张哲宇[3] 颜丽丽 ZHOU Bing-rui;PAN Bo;YUN Sung-hyo;CHANG Cheol-woo;YAN Li-li(Jilin Changbaishan Volcano National Observation and Research Station,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Key Laboratory of Seismic and Volcanic Hazards,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Institute of Environmental Studies,Pusan National University,Busan 46241,Republic of Korea)

机构地区：[1]吉林长白山火山国家野外科学观测研究站,中国地震局地质研究所,北京100029 [2]中国地震局地震与火山灾害重点实验室,北京100029 [3]釜山大学环境研究所,韩国釜山46241

出　　处：《地震地质》2022年第4期831-844,共14页Seismology and Geology

基　　金：国家自然科学基金(41911540472);韩国国家研究基金委项目(NRF-2019K2A9A2A06025294)共同资助。

摘　　要：长白山天池火山是一座大型的复合式活火山,公元946—947年发生的大喷发和2002—2005年的岩浆扰动事件,使其受到社会和学者的高度关注。然而,目前对天池火山的岩浆演化过程,尤其是玄武岩—粗安岩—粗面岩—碱流岩的演化过程还未能获得良好的认识,存在诸多争议。文中通过大量野外工作,获得了天池火山各阶段的岩石样品,对其进行了全岩地球化学测试与分析。结果显示,不同喷发阶段的火山岩主量元素随着岩浆硅含量的上升有着连续渐变的趋势,稀土及微量元素的分布也具有一致性,反映了一个连续的演化过程。同时,文中基于MELTS模型对天池火山的岩浆演化进行了模拟,模拟结果与天池火山的演化过程具有良好的吻合性,并发现粗面岩向碱流岩的演化过程中除经历分离结晶作用外,还遭到了浅部地壳花岗岩的同化混染。这些对天池火山岩浆演化过程的新认识,加深了对天池火山发展演化过程的理解,也为未来火山喷发的灾害预警和监测数据解释提供了理论支撑。Changbaishan-Tianchi volcano(CBS-TC), located in Jilin Province on the border between China and North Korea, is the largest composite volcano around China, which is still active. The eruption stages of this large Quaternary composite volcano can be roughly divided into 2.0~1.48 Ma shield forming stage, 1.48~0.05 Ma cone forming stage and the explosive eruption stage since 50 000 years ago. Its great eruption activities(the Millennium Eruption)from 946 AD to 947 AD and magmatic disturbances from 2002 to 2005 have attracted great attention of the government and scholars.Predecessors have done a lot of researches on Tianchi volcano, including its eruption periods, distribution of eruptive products, disaster assessment and so on. Geophysical data show that there are anomalies in the lower part, indicating the existence of magma chambers or conduits, but the accurate boundary and depth of magma chambers need to be further explored. The study of petro-geochemistry shows that the products of shield forming stage of Tianchi are mainly potassic trachy-basalts. The MgOof these basic magma is lower than that of the primary magma in Northeast China, indicating that they are the evolved magma undergoing the process of fractional crystallization. In the past, the cone forming stage was considered to have the characteristic of “bimodal” eruptions, that is, the cone forming eruptions of high SiOtrachytic/comenditic magma was accompanied by the low SiObasaltic magma, which formed small cinder cones on the edifice. In recent years, some drilling data show that there are thick basaltic trachy-andesite and trachy-andesite strata under the cone, indicating that the products of the cone forming stage of Tianchi include early basaltic trachy-andesite, medium trachy-andesite and late trachyte. Their SiOand NaO+KO contents are increasing with the degree of evolution. Since the late Pleistocene, Tianchi volcano has entered the stage of explosive eruptions with strong caldera forming effect. The eruptive products are mainly comenditic/

关 键 词：长白山天池 地球化学 热力学模拟 连续演化 同化混染 

分 类 号：P317[天文地球—固体地球物理学] P59[天文地球—地球物理学]