吉林省靖宇县龙泉龙湾火山第三期喷发的火山碎屑物堆积特征及其形成机制  

Characteristics and mechanism of pyroclastic deposits in the third‑stage eruption of Longquanlongwan volcano,Jingyu County,Jilin Province

作　　者：孙玉菁 刘永顺[1] 聂保锋[1] 冯玮霞 江姗 李冰 Sun Yujing;Liu Yongshun;Nie Baofeng;Feng Weixia;Jiang Shan;Li Bing(College of Resource,Environment and Tourism,Capital Normal University,Beijing 100048)

机构地区：[1]首都师范大学资源环境与旅游学院,北京100048

出　　处：《地质科学》2025年第2期428-445,共18页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金项目(编号:41372343)资助。

摘　　要：射气岩浆喷发的火山碎屑物特征和形成机制的研究,一直是火山喷发动力学和火山沉积学研究的重要主题。本文针对吉林省靖宇县龙泉龙湾火山第三期喷发的火山碎屑物及其堆积物特征,开展了显微岩相学和粒度与粒形分析,并根据多段幂律分布方法对火山碎屑物的分形特征进行了研究,在此基础上反演了火山喷发的复杂机制。本文所研究的典型剖面可分为上、下部的基浪堆积物层与中部空落浮岩质火山碎屑夹层。中部空落浮岩质火山碎屑夹层的粒径峰值较大,为单峰式分布;上、下部基浪堆积物层的粒径峰值较小,大部分为单峰式分布,也存在双峰式分布,爆炸成因较复杂。中部空落浮岩质火山碎屑夹层主要受岩浆初始破碎、浅层二次破碎、高能二次破碎和风力搬运沉积作用的影响。射气岩浆喷发时,碎屑化过程主要涉及挥发分出溶导致的岩浆碎屑化过程,岩浆—水相互作用导致的脆性断裂过程以及火山碎屑涌浪内部的碎屑化过程;堆积物表现为细粒火山灰—火山砂层与粗粒火山砾—火山砂—火山灰层的层状韵律,层理清晰,展现层凝灰岩的特征。The pyroclastic features and formation mechanism of phreatomagmatic eruption has been an important topic of volcanic eruption dynamics and volcanic sedimentology.In this paper,micropetrography and particle size and shape characteristics were conducted on the pyroclasts and their deposits in the third‑stage eruption of the Longquanlongwan volcano,Jingyu County,Jilin Province.The fractal characteristics of pyroclasts were studied according to the multi‑segment power‑law distribution method,and the complex mechanism of volcanic eruption was inverted on this basis.The typical profiles studied in this paper can be divided into the upper and lower base surge deposit layers and the air‑fall scoria pyroclast interlayers between them.The particle size peaks of the air‑fall scoria pyroclast interlayers area large and unimodal.The particle size peaks of the upper and lower base surge deposits are very small and inconsistent,most of distributions are unimodal with bimodal distributions,and their pyroclast cause of explosion is complicated.The central air‑fall scoria pyroclast interlayer is mainly affected by the initial magma fragmentation,shallow secondary fragmentation,high‑energy secondary fragmentation and wind transport sedimentation.During the phreatomagmatic eruption,the fragmentation processes mainly involve the magmatic fragmentation process caused by the volatile exsolution,the brittle fracture process caused by the magma‑water interaction,and the fragmentation process inside the pyroclastic surge.Their deposits show the clear rhythmic strata of fine volcanic ash‑sand layers and coarsed‑grained volcanic lapilli‑sand‑ash layers.

关 键 词：龙泉龙湾火山 射气岩浆喷发 火山碎屑物堆积 分形维数 火山喷发机制 

分 类 号：P588.211[天文地球—岩石学]