Magmatic processes of the Millennium eruption at Changbiashan Tianchi volcano, China/North Korea

作者：Pan Bo^*; Fan QiCheng; Xu JianDong; Wu ChengZhi; Chen ZhengQuan; Guo Feng

来源：Acta Petrologica Sinica, 2017, 33(1): 163-172.

• Tianchi volcano
• Millennium eruption
• Comenditic eruption phase
• Trachytic eruption phase
• Magma mixing
• Model of magmatic process

Changbaishan Tianchi volcano on the border of China and North Korea is one of the most dangerous volcanoes in China and Northeast Asia. The Millennium eruption was considered as the youngest large-scale explosive eruption in China. After the recently geological survey around the caldera, we found the Millennium eruption has the comenditic and trachytic deposits with the magma mixing pumices showing the black and grey bands. Utilizing the further petrographic and geochemical studies, two eruptive phases have been identified out the "Millennium" eruption, comenditic eruptive phase (SiO2, 75%) and trachytic eruptive phase (SiO2, 65%). Meanwhile, the comenditic and trachytic magma were stored in two unconnected and separated chambers before eruption based on the entirely different feature on the trace element of the glasses and phenocrysts. The comenditic magma chamber was steadily stored and evolved in about 5km depth with 743 degrees C under the Tianchi caldera; while the trachytic magma chamber existed in 7 similar to 9km depth with 862 degrees C and was incrementally supplied with new magma from deeper source. In addition, the characteristics of the magma mixing strips suggest the mixing occurs in the rising channel excluding the possibility of chamber mixing. Finally, we build the model for the magmatic processes of the Millennium eruption based on the above results. In a word, we hope this improved recognition on the magmatic processes will benefit on the understanding of volcanic activity and assessment of volcanic hazards in future.

• 出版日期2017-1
• 单位中国地震局