长白山天池火山千年大喷发的岩浆过程  

Magmatic processes of the Millennium eruption at Changbiashan Tianchi volcano,China/North Korea

作　　者：潘波[1] 樊祺诚[1] 许建东[1] 武成智 陈正全[1] 郭峰 PAN Bo FAN QiCheng XU JianDong WU ChengZhi CHEN ZhengQuan GUO Feng(Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China Changbaishan Tianchi Volcano Observatory, Antu 133613, China)

机构地区：[1]中国地震局地质研究所活动构造与火山重点实验室,北京100029 [2]吉林省长白山天池火山监测站,安图133613

出　　处：《岩石学报》2017年第1期163-172,共10页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41302267);中国地震局地质研究所基本科研业务专项(IGCEA1505)联合资助

摘　　要：千年大喷发是长白山天池火山最近的一次大规模爆炸式喷发活动。本文在天池火口及周边的地质调查中发现,千年大喷发存在碱流质和粗面质两套堆积物,且具有岩浆混合现象。进一步岩相学与地球化学研究,证实千年大喷发应存在先后两个喷发阶段,即碱流质喷发阶段(SiO_2,~75%)和粗面质喷发阶段(SiO_2,~65%)。同时,通过微量元素和斑晶特征等分析认为两阶段的岩浆来自于两个独立的岩浆房,岩浆房平衡温度分别为743℃和862℃,相应深度约为5km和7~9km。另外,根据条带状岩浆的混合特征,认为喷发过程中碱流质与粗面质岩浆混合发生在上升通道中,排除岩浆房内混合的可能性。最后根据喷发过程和岩浆特征,综合提出了千年大喷发的岩浆过程模型。本文对千年大喷发的喷发过程和岩浆过程取得的新认识,增进了对天池火山活动习性的理解。Changbaishan Tianchi volcano on the border of China and North Korea is one of the most dangerous volcanoes in China and Northeast Asia. The Millennium eruption was considered as the youngest large-scale explosive eruption in China. After the recently geological survey around the caldera, we found the Millennium eruption has the comenditic and trachytic deposits with the magma mixing pumices showing the black and grey bands. Utilizing the further petrographic and geochemical studies, two eruptive phases have been identified out the ＂Millennium＂ eruption, comenditic eruptive phase （SiO2, 75%） and trachytic eruptive phase （SiO2, 65%）. Meanwhile, the comenditic and trachytic magma were stored in two unconnected and separated chambers before eruption based on the entirely different feature on the trace element of the glasses and phenocrysts. The comenditic magma chamber was steadily stored and evolved in about 5km depth with 743℃ under the Tianchi caldera; while the trachytic magma chamber existed in 7~9km depth with 862℃ and was incrementally supplied with new magma from deeper source. In addition, the characteristics of the magma-mixing strips suggest the mixing occurs in the rising channel excluding the possibility of chamber mixing. Finally, we build the model for the magmatic processes of the Millennium eruption based on the above results. In a word, we hope this improved recognition on the magmatic processes will benefit on the understanding of volcanic activity and assessment of volcanic hazards in future.

关 键 词：天池火山 千年大喷发 碱流质喷发阶段 粗面质喷发阶段 岩浆混合 岩浆过程模型 

分 类 号：P317.3[天文地球—固体地球物理学]