长白山火山区壳幔物性结构与深部物理场特征

Physical property structure of the crust-mantle and deep geophysical feature in Changbaishan volcanic area

长白山火山是一座具有潜在喷发危险的大型近代活动火山,因此通过对该火山活动的监测,加强对长白山天池火山岩浆系统的研究并了解天池火山的活动性质是很有意义的.除了开展长白山火山活动历史、火山地层学、火山岩岩石学、年代学以及火山地质等研究之外,我国从20世纪80年代开始在该火山区域进行了一系列的地球物理探测活动.为深入了解长白山火山区岩浆的分布与活动特征,本文对前人工作进行总结,得到了关于长白山火山活动的以下几个方面的认识:1)通过火山区地震活动性监测得到了火山区的岩浆活动状态;2)利用大地电磁测深对火山区地下是否存在可能再次活动的岩浆囊及其分布形态进行监测,为火山喷发的危险性预测和灾害评价提供依据;3)利用人工源深地震测深对长白山天池及其邻域的结晶基底及地壳精细结构进行讨论;4)利用天然地震对火山区地壳、上地幔结构进行深入研究,分析了与火山区有关的深层动力学因素;5)对国外火山区重力监测实例的调研表明,重力监测对了解岩浆活动状态是十分有效的手段.多种地球物理方法的综合应用,获得了长白山火山地区地壳至地幔转换带的详细资料.

Changbaishan volcano is a major active modern volcano with potential danger of eruption. So it is meaningful to enhance the systematic study of Changbaishan Tianchi magama system and learn the nature of its activity through monitoring volcanic activities. Besides from the study of volcanic activities history, volcanostratigraphy, volcanic petrology, volcanic chronology and geology, we carried out a series of geophysical survey in this area from the 1980s. For the purpose of further understanding the magama distribution and activity feature of Changbaishan area, we summarize former works and obtain the following conclusions： 1 ） learn the magama activity status through seismieity monitor; 2 ） using magnetotelluric survey to identify whether exists potential active magama chamber and its distributing range, offering basis for eruption dangerousness prediction and hazard evalution; 3 ） using Deep Seismic Sounding to discuss the crystalline basement and fine crustal structure of Changbaishan Tianehi volcano and its adjacent area; 4） using natural earthquake to lucubrate the crustal-mantle structure and deep dynamic factors related to volcanic area; 5 ） offering an example abroad to indicate that gravity monitor is an effective way of learning magama status. By comprehensively using multiple geophysical methods, we derive detailed information from crust to mantle transition zone in Changbaishan volcanic area.