内蒙古锡林浩特地区晚新生代火山喷发序列研究  

Late Cenozoic sequence of volcanic eruptions in the Xilinhot area,Inner Mongolia

作　　者：史志伟 白志达[1] 赵志丹[1] 董国臣[1] 王建伟[1] 金笃斌 SHI ZhiWei;BAI ZhiDa;ZHAO ZhiDan;DONG GuoChen;WANG JianWei;JIN DuBin(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《岩石学报》2024年第7期2087-2102,共16页Acta Petrologica Sinica

基　　金：内蒙古锡林浩特市自然保护地管护中心项目(2022KY0810)资助。

摘　　要：火山喷发序列是恢复火山活动历史的重要基础。锡林浩特火山群是大兴安岭-大同新生代火山喷发带中火山数量最多、喷发时间最长的火山群。本文从火山地质学入手,查明了火山堆积物之间及与沉积地层(离石黄土、马兰黄土和黑土)的叠置关系,并根据火山结构组成、形貌特征、喷发类型、火山岩类型及火山锥体的风化降解程度等,结合光释光(OSL)、^(14)C等定年方法,对火山喷发序列进行综合研究,确定了喷发相对时序和绝对年龄。锡林浩特火山群火山活动具有周期性变化规律,其喷发序列由老到新依次为:上新世,早更新世,中更新世早期、中更新世晚期,晚更新世早、中、晚和末期,以及全新世,共9个火山喷发旋回。晚更新世是火山喷发的鼎盛时期。首次确定了鸽子山火山的最晚喷发年龄距今约6800年,为广义活火山。不同旋回火山喷发方式及火山风化降解程度差异较大。上新世为裂隙式喷发,早、中更新世主要是裂隙-中心式喷发,晚更新世以来为中心式喷发。中心式喷发火山类型有斯通博利型、夏威夷型、玛珥型和亚布里尼型,其中玛珥型火山在本区属首次发现。中更新世及以前的火山锥基本已剥蚀殆尽,晚更新世以来的火山地貌形态保存尚好。每个喷发旋回几乎都呈现从碱性玄武岩向拉斑玄武岩演化的特征,反映了本区深部岩浆房演化与构造活动强度的周期性变化规律。The sequence of volcanic eruptions is crucial for reconstructing the history of volcanic activity.The Xilinhot volcanic group stands out as having the greatest number of volcanoes and the longest duration of eruptions in the Cenozoic volcanic eruption zone of the Great Xing an Range-to-Datong.This paper starts with the volcanic geology and identifies the superimposition relationship between volcanic deposits and sedimentary strata(e.g.,Lishi loess,Malan loess and black soil).The volcanic eruption sequence is comprehensively studied,and the relative timing and absolute age of eruptions are determined based on the volcanic structure,composition,morphological features,eruption types,volcanic rock types,and weathering degradation degree of volcanic cones,combined with optically stimulated luminescence(OSL)and ^(14 )C dating methods.The Xilinhot volcanic group exhibits periodic changes in activity.The eruption sequence,in order from oldest to most recent,is as follows:Pliocene,Early Pleistocene,Middle Pleistocene(early and late stages),Late Pleistocene(early,middle,late,and end stages),and Holocene,totaling 9 eruption cycles.The Late Pleistocene was the period of highest volcanic activity.The most recent eruption age of the Gezishan volcano has been determined to be approximately 6800 years ago,confirming its status as a generalized active volcano.There are notable variations in eruption types and the degree of volcanic weathering and degradation among different cycles.Fissure eruptions occurred during the Pliocene,while fissure-central eruptions were predominant in the Early and Middle Pleistocene.Central eruptions occurred during the Late Pleistocene.The central-eruption volcanoes encompass various types,including Strombolian,Hawaiian,Maar,and Sub-Plinian eruptions.Notably,the discovery of Maar-type volcanoes in this area is a novel finding.The volcanic cones from the Middle Pleistocene and earlier have been almost completely eroded,while the volcanic landforms since the Late Pleistocene have been well preserved.Eac

关 键 词：晚新生代 喷发序列 喷发类型 鸽子山活火山 锡林浩特 

分 类 号：P317.3[天文地球—固体地球物理学] P588.14[天文地球—地球物理学] P597.3