摘要
五大连池老黑山火山曾在公元1720-1721年喷发,熔岩出露面积60.2km^(2)。老黑山具有我国境内最新喷溢的熔岩流区,使其成为研究单成因火山熔岩表壳类型、熔岩传输系统和熔岩流灾害的理想对象。老黑山火山喷发兼具爆炸性与溢流性,以溢流性为主。本文使用0.05~0.92m/pix无人机航拍数据和12.5m/pix卫星数据,在实地验证的基础上,制作了11000比例尺熔岩流分布过程图。我们将老黑山的6个熔岩流区界定为相应熔岩溢出口的产物,并区分出每个熔岩流区内部的亚区和岩流组。本文归纳出不同尺度熔岩流边界界定的2个标准:(1)熔岩流区的边界界定,需要以大尺度的地形凹陷和沟谷为线索,以熔岩趾分布和压盖关系辅助确定;(2)熔岩流区内部岩流组的界定,更多地依赖于熔岩表壳相组合分析,并辅以地形特征确定。通过对岩流表壳相的分析,本文总结出老黑山熔岩流主要由渣状岩流传输模式主导,同时具有结壳岩流传输和膨胀传输类型。根据老黑山不同岩流的分布和传输特征,我们提出了使用逐层、逐组估算岩流体积的方法。老黑山火山爆炸性碎屑物体积为70×10^(6)m^( 3),爆炸性喷发指数VEI=1~2;熔岩流体积为290×10^(6)m^( 3),溢流式喷发的等级(magnitude)为4.9。根据与Puu Oo 1983-84岩流特征进行对比,推测老黑山喷发烈度为弱-中等(intensity=4~8)。
The Laoheishan volcano in Heilongjiang Province,NE China,erupted in 1720-1721AD.The eruption of Laoheishan volcano show typical Hawaiian and Strombolian eruptive styles.The lava flow field of Laoheishan volcano covers an area of 60.19km^(2).Due to it preserves the newest lava flows in China,it is an ideal case to investigate the lava surface morphologies,lava transport system,and lava-flow-hazard processes of monogenetic basaltic volcanism.We use 0.05~0.92m/pix image data acquiring from small Unoccupied Aircraft Systems(UAS)and 12.5m/pix satellite image,to create a 11000 scale flow processes map that was ground-truthed by field observations.In order to understand the flow process,we defined six lava flow fields as the products of the corresponding lava outlets.Moreover,we distinguished the sub-flow field,lava flow sets(a set of lava flows originated from the same bocca of their parent flow)and flow units within each lava flow field.In this paper,two criteria for the boundary demarcation of lava flows at different scales summarized as below.(1)The boundary of the flow field(i.e.,lava from the same outlet)mostly defined by the large topographic depression and valley.The distribution and stratigraphic contact of lava toes provide evidences for the demarcation work.(2)The demarcation of the flow units within a flow field depends more on the assembly of lava surface facies,and the boundary is determined with the assistance of small topographic features.We concluded that there are three types of lava transportation in Laoheishan lava flow field:aāflow,pāhoehoe flow and inflation behaviors,by analyzing the surface facie of specific lava flows.We found the aāflow behavior dominated in Laoheishan lava flow field.In this way,a large portion of the Laoheishan lava flow field(s)were divided into relative small units,by a model that pāhoehoe toes developed from its aāparent.In addition,significant pāhoehoe and inflation processes also taken place in somewhere.We propose a layer-by-layer and set-by-set estimation method
作者
陈正全
赵勇伟
CHEN ZhengQuan;ZHAO YongWei(Jilin Changbaishan Volcano National Observation and Research Station,Institute of Geology,China Earthquake Administration,Beijing 100029,China;MOE Key Laboratory of Intraplate Volcanoes and Earthquakes,China University of Geosciences(Beijing),Beijing 100083,China;Key Laboratory of Seismic and Volcanic Hazards,China Earthquake Administration,Beijing 100029,China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第7期2056-2074,共19页
Acta Petrologica Sinica
基金
中央级公益性科研院所基本科研业务专项(IGCEA1916)
国家自然科学基金项目(41802252)联合资助.
关键词
五大连池
老黑山
岩流
表壳类型
熔岩传输
体积估算
Wudalianchi
Laoheishan
Flow set
Lava surface types
Lava transport
Volume estimate
