Effect of gas emissions from Tianchi volcano (NE China) on environment and its potential volcanic hazards

Abstract

The Tianchi volcano in the Changbai Mountains is located on the boundary between China and North Korea. There are many times of eruptions of the Tianchi volcano during the Holocene. One of its large eruptions occurred around 1000 years ago dated by 14 C method and historical records. Composition of products of the largest Tianchi volcanic eruption studied is characterized by comenditic Plinian fallout and unwelded ignimbrite, which are mainly distributed in China and North Korea. Caldera is about 4.4 km long and 3.4 km wide, which had filled with water (e.g. Tianchi Lake). The Tianchi volcanic cone is about 2700 m high above sea level. The Tianchi Lake is located on the summit of the volcanic cone, that is also highest peak of the Changbai Mountains in northeastern China. This study analyzed Cl, F, S and H 2 O concentrations of melt inclusions in the phenocryst minerals (anorthoclase and quartz) and co-existing matrix glasses using the electron microprobe and estimated environmental effect of Tianchi volcanic gases. The authors proposed a new method to evaluate future eruption of active volcano and estimate potential volcanic hazards based on contents of volatile emissions. Using this method, we made a perspective of future volcanic hazard in this region.

Effect of volatiles erupted from Mesozoic and Cenozoic volcanic activities on paleo-environmental changes in China

“…Melt inclusion within the phenocrysts for the analysis should be primary and colorless; the melt glasses would be fresh and free of micro-crystals . More detailed features of melt inclusions and melt glasses are consistent with the criteria shown (Horn and Schmincke, 2000;Guo et al, 2003c;Guo et al, 2006). The operating conditions of the microprobe analyses (Guo et al, 2006) are as follows: 15-20 kV accelerating voltage, 5-20 nA current, 1-10 mm electron beam in diameter for melt inclusion and 10-20 mm for melt glasses.…”

“…More detailed features of melt inclusions and melt glasses are consistent with the criteria shown (Horn and Schmincke, 2000;Guo et al, 2003c;Guo et al, 2006). The operating conditions of the microprobe analyses (Guo et al, 2006) are as follows: 15-20 kV accelerating voltage, 5-20 nA current, 1-10 mm electron beam in diameter for melt inclusion and 10-20 mm for melt glasses. Relative analytical precision was F , 2%, Cl , 4% and S , 5% on the basis of repeated analyses of international standards and samples.…”

“…Relative analytical precision was F , 2%, Cl , 4% and S , 5% on the basis of repeated analyses of international standards and samples. More detailed procedures follow those of the references (Guo et al, , 2003cGuo et al, 2006). Total H 2 O concentration of melt inclusions and melt glasses were estimated by the difference between the total of an electron microprobe analysis and 100% (so called ''difference method'') (Guo andLiu, 2002, Guo et al, 2003c).…”

“…Guo et al, , 2003cGuo et al, , 2006 have indicated that volatile content in melt inclusions of host mineral crystals may represent those trapped in the preeruption magmas, while concentrations of volatiles in melt glasses may represent contents of volatiles in posteruption magmas. Differences between content in the melt inclusions and co-existing melt glasses may be considered concentrations of volatiles erupted during the volcanic activities.…”

14C Wiggle-Matching of the B-Tm Tephra, Baitoushan Volcano, China/North Korea

“…The Baitoushan-Tomakomai (B-Tm) tephra, which erupted from Baitoushan Volcano (also known as Paektusan and/or Changbaishan) on the border between present-day China and North Korea, reached the northeastern part of the Japanese Islands ( Figure 1A; Machida et al 1981Machida et al , 1990Machida and Arai 1983;Horn and Schmincke 2000;Guo et al 2006). Machida (1992) proposed that the eruption influenced the fall of the Bo-hai Kingdom, which occupied the volcano and its adjacent areas in AD 926.…”