Growth and thermal maturation of the Toba magma reservoir
Document Type
Article
Publication Date
11-9-2021
Abstract
The Toba volcanic system in Indonesia has produced two of the largest eruptions (>2,000 km(3) dense-rock equivalent DRE] each) on Earth since the Quaternary. U-Pb crystallization ages of zircon span a period of similar to 600 ky before each eruptive event, and in the run-up to each eruption, the mean and variance of the zircons' U content decrease. To quantify the process of accumulation of eruptible magma underneath the Toba caldera, we integrated these observations with thermal and geochemical modeling. We show that caldera-forming eruptions at Toba are the result of progressive thermal maturation of the upper crustal magma reservoir, which grows and chemically homogenizes, by sustained magma influx at average volumetric rates between 0.008 and 0.01 km(3)/y over the past 2.2 My. Protracted thermal pulses related to magma-recharge events prime the system for eruption without necessarily requiring an increased magma-recharge rate before the two supereruptions. If the rate of magma input was maintained since the last supereruption of Toba at 75 ka, eruptible magma is currently accumulating at a minimum rate of similar to 4.2 km(3) per millennium, and the current estimate of the total volume of potentially eruptible magma available today is a minimum of similar to 315 km(3). Our approach to evaluate magma flux and the rate of eruptible magma accumulation is applicable to other volcanic systems capable of producing supereruptions and thereby could help in assessing the potential of active volcanic systems to feed supereruptions.
Keywords
Toba caldera, supereruption, eruptible magma, thermal modeling, zircon
Divisions
GEOLOGY
Funders
Chinese Academy of Sciences [Grant No: XDB18030300],National Natural Science Foundation of China (NSFC) [Grant No: 41872058],European Research Council under the European Union's Horizon 2020 Research and Innovation Program [Grant No: 677493],Swiss National Science Foundation (SNSF) European Commission
Publication Title
Proceedings of the National Academy of Sciences of the United States of America
Volume
118
Issue
45
Publisher
Natl Acad Sciences
Publisher Location
2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA