Volcanic activities in the Tengchong volcano area since Pliocene
腾冲火山区上新世以来的火山活动

Systematic K-Ar Dating has been yielded for Pliocene-Recent volcanic eruptions in the Tengchong volcano area, mainly for latest eruptions of Heikongshan, Dayingshan and Maanshan craters. After distignishing plagioclase-phenocryst and olivine-phenocryst with excess argon from samples, a series age of the matrix of volcanic rocks has been obtained. From time-space exchanges and distribution, the activities of the Tengchong volcano could be divided into three stages. The first stage developed in the late Pliocene, when the volcanic eruptions occurred in southeastern and northwestern ends of the Tengchong volcano area. The second stage experienced in the early Pleistocene suggests that the volcanic activities were migrated and transferred to central areas of the basin. At this stage, volcanic scale and distribution were largest compared with that in other stages. The third stage occurred during the early Pleistocene-Holocene. During the late of Early Pleistocene-Middle Pleistocene, volcanic scales were decreased, and mainly distributed on a NS-trending belt in the center of the Tengchong basin. Since late Pleistocene, the volcanic activities have been focused on Heikongshan, Dayingshan, and Maanshan areas. There was volcanic activity in Maanshan area in the Holocene. The third volcanic stage is characterized as from central-northern to southern parts, it qets younger and younger. This means that the volcanic activities are transferred from north to south.