摘要
根据琼北全新世火山区内火山作用产物的成因类型与喷发物理过程的野外考察结果 ,结合航片解译资料 ,确定了该区火山作用的发育特征、形成期次与规模 ,并以此作为进一步评价火山灾害的基础 ;根据锥体形成后物理降解作用与时间的关系 ,讨论了琼北全新世火山区众多锥体结构参数之间的关系。研究结果为 :琼北全新世火山区分为 4个火山系统 ,即西北部的马鞍岭台地火山系统、东南部的雷虎岭盾片状火山系统、夹于二者之间的浩昌单成因火山系统和NW向裂隙式喷发系统。工作区内琼北新生代火山共计 5 9个 ,火山结构类型可分为火山锥、熔岩穹、熔岩湖与低平火山口等。在火山锥中 ,依据锥体组成与结构的差异又可进一步分为岩渣锥、溅落锥和混合锥等碎屑锥。琼北近代火山锥体高度多 <4 0m ,绝大多数锥体的底部直径 <5 0 0m。锥体底部直径和火口坑深度之间具有明显的正相关关系。
The Holocene volcanoes in the northern Hainan Island can be divided into 4 systems. These 4 systems include Maanling plateau volcanic system in the northwest part, Leihuling shield volcanic system in the southeast, Haochang monogenic volcanic system in between, and the NW-trending fissure eruption system. The Maanling plateau volcanoes consist of 4 cones and the related lava flows that flow to the northwest, southwest, and northeast, respectively. The Leihuling volcanoes are composed also of cones and lavas. The cones are located on Leihuling, Qunxiuling, and Qunzhongling, while the lava flows are the largest in the whole region, extending northeastward to Yongxing, Bochang, Shapo Reservoir, Bopiancun and Longqiao, and southward to Changgan, Meiqiu, Fenghuang, and Meixingcun. There are 59 Cenozoic cones, the volcanic texture of which may be classified into cone, dome, lava lake and maar. Based on the composition and texture differences of the cones, the cones have been subdivided into scoria cone, spatter cone and mixed cone. The height of the cones is generally less than 40 m, and the diameter of most of the cone bases is less than 500m. There is a linear relation between the cone base diameter and the depth of the crater. We can thus distinguish the different cones that were formed at different times by plotting the height of the cone versus the difference between the crater rim diameter and cone base diameter. We have successfully distinguished the early-formed maars from the later-formed cones of different types.
出处
《地震地质》
EI
CSCD
北大核心
2003年第B12期21-32,共12页
Seismology and Geology
基金
科技部社会公益项目研究专项资金 (2 0 0 0DIA10 2 0 0 3)资助
关键词
全新世
火山系统
划分
锥体结构参数
琼北
Holocene volcanic system, structural parameter of cone, northern Hainan Island
