美国夏威夷天文台Bennington, N.课题组报道了黄石破火山口玄武岩-流纹岩熔体储层演化。这一研究成果于2025年1月1日发表在国际顶尖学术期刊《自然》上。

研究人员利用大地电磁数据模拟了黄石破火山口地壳岩浆储层的电阻率结构，并限制了该地区产生大型火山喷发的潜力。研究发现，流纹岩熔体储存在火山口下方的分离区域，熔体含量低，表明储层不具有喷发性。通常，这些地区的融化量相当于黄石火山爆发后的小体积喷发。

最大的流纹岩熔体储存区域集中在黄石火山口东北部，其储存量与黄石最小的火山口形成喷发的喷发量相似。研究确定了玄武岩从下地壳迁移的玄武岩区域，与流纹岩熔体储存的东北区域融合并提供热量。在此基础上，研究人员推测，未来流纹岩火山活动的位置已经转移到黄石火山口的东北部。

据了解，黄石火山口是地球上最大的火山系统之一，在过去的两百万年里，它发生了三次形成破火山口的喷发，其间穿插着几次爆炸性较小、规模较小的喷发。黄石公园形成破火山口的喷发来源于储存在地壳中上部火成岩中的流纹岩熔体。地震层析成像研究表明，黄石火山口下延伸着一大片流纹岩熔体区，估计熔体体积比过去最大的火山口形成喷发的喷发体积大一到四倍，估计熔体比例为6-28％所示。地震速度受温度、压力和熔体的强烈影响；然而，大地电磁数据主要对熔体的存在敏感，使这些数据成为限制火山系统的理想选择。

附：英文原文

Title: The progression of basaltic–rhyolitic melt storage at Yellowstone Caldera

Author: Bennington, N., Schultz, A., Bedrosian, P., Bowles-Martinez, E., Lynn, K., Stelten, M., Tu, X., Thurber, C.

Issue&Volume: 2025-01-01

Abstract: Yellowstone Caldera is one of the largest volcanic systems on Earth, hosting three major caldera-forming eruptions in the past two million years, interspersed with periods of less explosive, smaller-volume eruptions. Caldera-forming eruptions at Yellowstone are sourced by rhyolitic melts stored within the mid- to upper crust. Seismic tomography studies have suggested that a broad region of rhyolitic melt extends beneath Yellowstone Caldera, with an estimated melt volume that is one to four times greater than the eruptive volume of the largest past caldera-forming eruption, and an estimated melt fraction of 6–28per cent. Seismic velocity is strongly influenced by temperature, pressure and melt; however, magnetotelluric data are primarily sensitive to the presence of melt, making these data ideal for constraining volcanic systems. Here we utilize magnetotelluric data to model the resistivity structure of Yellowstone Caldera’s crustal magma reservoir and constrain the region’s potential for producing major volcanic eruptions. We find that rhyolitic melts are stored in segregated regions beneath the caldera with low melt fractions, indicating that the reservoirs are not eruptible. Typically, these regions have melt volumes equivalent to small-volume post-caldera Yellowstone eruptions. The largest region of rhyolitic melt storage, concentrated beneath northeast Yellowstone Caldera, has a storage volume similar to the eruptive volume of Yellowstone’s smallest caldera-forming eruption. We identify regions of basalt migrating from the lower crust, merging with and supplying heat to the northeast region of rhyolitic melt storage. On the basis of our analysis, we suggest that the locus of future rhyolitic volcanism has shifted to northeast Yellowstone Caldera.

DOI: 10.1038/s41586-024-08286-z

Source: https://www.nature.com/articles/s41586-024-08286-z