五大连池火山群喷气锥成因机制探讨  

Discussion on genetic mechanism of hornitos in Wudalianchi volcanic field

作　　者：高危言[1] 李江海[1] 毛翔[1] 张天然[1] 

机构地区：[1]教育部造山带与地壳演化重点实验室,北京大学地球与空间科学学院,北京100871

出　　处：《岩石学报》2010年第1期309-317,共9页Acta Petrologica Sinica

基　　金：国家"973"重点基础研究发展计划项目(2009CB219302)资助

摘　　要：五大连池火山群1537个喷气锥中,多数分布在火烧山熔岩流中,在水量充足的五池到四池之间的熔岩台地上,喷气锥数量集中、个体较大、发育良好。通过对五大连池火山群喷气锥的形态结构和集中分布特点进行分析,认为水蒸气在混合气体形成喷气锥中起主导作用,重力也在喷气锥形态塑造上有一定意义。含挥发分的基性岩浆溢流到在靠近水域的地区时表层冷凝固结,内部熔岩仍温度高、粘度低,与地下水作用形成火山气体和水蒸气构成的混合气体,气体冲破表层间歇溢出时,带动熔岩外掀堆叠在喷气孔周围形成喷气锥,中央保留气体多次逸出的通道形成中空结构。当气体压力不足以使熔岩从喷口溢出,喷气锥的生长停止。Majority of 1537 hornitos in Wudalianchi volcanic field distribute in lava flows of Huoshaoshan.Especially,lava plateau between Fourth and Fifth pools with sufficient water,has hornitos concentrated distributed,in the largest scale and best developed. After morphologic and concentrated distribution characteristic analysis,it comes to the conclusion that vapor in mixed gas is dominant in the formation of hornito,and gravity is also of some importance to shape a hornito.When the basic lava with volatile overflowed near to water area,the surface of lava condensated and consolidated while inside remained high temperature and low viscosity.Mixed gas containing volcanic gas and vapor started to aggregate after lava meeting groundwater,and intermittently broke surface of lava to escape,together with some lava spattering up and stacking around the vent to form a hornito,the inside of which stayed hollow as the route way for gas to escape.When air pressure failed to eject lava from top jet,growth of a hornito ended.

关 键 词：五大连池火山群 喷气锥 基性岩浆 粘度 水蒸气 

分 类 号：P317.3[天文地球—固体地球物理学]