Magma plumbing system for the Millennium Eruption at Changbaishan volcano, China: Constraints from whole-rock U-Th disequilibrium

被引：13

作者：

Kuritani, Takeshi ^{[1
]}

Nakagawa, Mitsuhiro ^{[1
]}

Nishimoto, Jumpei ^{[1
,4
]}

Yokoyama, Tetsuya ^{[2
]}

Miyamoto, Tsuyoshi ^{[3
]}

机构：

[1] Hokkaido Univ, Grad Sch Sci, Sapporo, Hokkaido 0600810, Japan

[2] Tokyo Inst Technol, Grad Sch Sci, Tokyo 1528551, Japan

[3] Tohoku Univ, Ctr Northeast Asian Studies, Sendai, Miyagi 9808576, Japan

[4] Hokkaido Govt Shiribeshi Subprefectural Bur, Kutchan 0448588, Japan

来源：

LITHOS | 2020年 / 366卷

关键词：

Caldera; Changbaishan volcano; Explosive eruption; Magma plumbing system; U-Th disequilibrium; TIANCHI VOLCANO; CHINA/NORTH KOREA; BAEKDUSAN CHANGBAISHAN; ISOTOPIC ANALYSIS; NORTHEAST CHINA; HALF-LIVES; EVOLUTION; THORIUM; SAMPLES; ZIRCON;

D O I：

10.1016/j.lithos.2020.105564

中图分类号：

P3 [地球物理学]; P59 [地球化学];

学科分类号：

0708 ; 070902 ;

摘要：

A caldera-forming eruption in 946 CE, known as the Millennium Eruption (ME), at Changbaishan (or Baekdusan) volcano, located on the border between China and North Korea, was one of the largest explosive eruptions on Earth in the last 2000 years. In this study, we obtained new whole-rock Sr, Nd, and Pb isotopic data and U-238-230Th disequilibrium data of representative volcanic products of the ME, as well as those of a pre-ME (4-5 ka) eruption, to understand the evolution of the magma plumbing system related to the caldera-forming eruption. The volcanic products of the ME have SiO2 contents ranging from similar to 54 to similar to 75 wt%, and the whole-rock (Th-230/Th-232) ratios tend to decrease systematically from basaltic trachy-andesite through trachyte to comendite. The relatively high (Th-230/Th-232) ratios of the felsic (trachytic and comenditic) volcanic products suggest that they were formed primarily from fractional crystallization of mafic magmas, rather than from partial melting of crustal materials. The basaltic trachy-andesite sample has a distinctly high (Th-230/Th-232) ratio and the least radiogenic Pb isotopic ratios among ME volcanic products, suggesting that the mafic magma was recently introduced into the main felsic magma system and is hypothesized to have triggered the eruption. The lower (Th-230/Th-232) ratios of the comendite samples than those of the trachyte samples, as well as published U-series disequilibrium data, suggest that the comendite magmas were produced by mixing old (> similar to 23 ka) and young (<similar to 6 ka) comenditic magmas. The old comendite magma was the main component of ME volcanic products. Pre-ME pantelleritic magmas with distinctly low (Th-230/Th-232) and high Sr-87/Sr-86 ratios from those of ME magmas may have formed a short-lived magma chamber until similar to 4-5 ka, which was isolated from the long-lived, main comendite magma chamber. (C) 2020 Elsevier B.V. All rights reserved.

引用

页数：11