龙岗火山群第四纪爆破式火山作用类型与期次研究

龙岗火山群位于吉林省辉南和靖宇县境内的龙岗山脉中段。火山活动始于新近纪，第四纪更新世为鼎盛期，全新世以来仍有较强的喷发活动，是中国近代活动火山区之一。火山碎屑物的堆积构造、组成、显微形貌和粒度特征表明，第四纪爆破式火山作用包括岩浆爆发、射汽一岩浆爆发和射汽爆发三种类型，以岩浆和射汽-岩浆爆发最为发育。区内爆破式火山活动具有多旋回、多期次、多阶段喷发特点。据火山地质特征，可划分为9期，由老至新为：早更新世早期、晚期；中更新世三角龙湾期、旱龙湾期和金龙顶子早期；晚更新世金川东期；全新世大翁圈期、红期林场期和金龙顶子晚期。爆破式火山灾害的范围较大，岩浆爆发中高危区的半径约10km。射汽-岩浆爆发影响的半径约4km。

Study on type and phase of Quaternary explosive volcanism in Longgang volcanic duster.

Longgang volcanic cluster is located in Huinan and Jingyu counties and belongs to the middle segment of the Longgang mountains range. Volcanic activities began in Neogene, and gained the prime of its life in Quarternary. Relative strong eruptions still occurred since Holocene. The features of depositional structure, components, micromorphology and grain size of pyroclastic materials show that the Quaternary explosive activities involve magmatic explosions, phreatomagmatic explosions and phreatic explosions. Magmatic explosions, phreatomagmatic explosions have the highest magnitude. Multi-cycle, multi-episode and multi-stages characterize the explosive activity of this cluster together. The Quaternary explosions can be divided into 9 stages according to the volcano-geological features. The hazard coverage of explosive volcanoes is great. The radius of middlehigh hazardous area resulted from a magmatic explosion is about 10km, while the radius involved in a phreatomagmatic explosion is about 4km.