Melt inclusion constraints on volatile systematics and degassing history of the 2014-2015 Holuhraun eruption, Iceland
Melt inclusion constraints on volatile systematics and degassing history of the 2014-2015 Holuhraun eruption, Iceland
复制标题
熔体包裹体对2014 - 2015年冰岛霍卢赫拉翁火山喷发的挥发分系统特征及脱气历史的限制
DOI：
10.1007/s00410-017-1434-1
复制
发表时间：
2018-02-01
影响因子：
3.5
通讯作者：
Jakobsson, S.
中科院分区：
文献类型：
--
作者：
Bali, E.;Hartley, M. E.;Jakobsson, S.
火山爆发期间释放的挥发物的质量通常通过比较在岩浆演化的早期阶段被困在晶体中的未脱气熔融包裹体的挥发物含量与脱气基质玻璃的挥发物含量来估计。在这里，我们提出了详细的表征的岩浆挥发物（H2O，- CO2，S，FI和Cl）的晶体托管熔体和流体包裹体从2014-2015 Holuhraun喷发的Baroarbunga火山系统，冰岛。根据岩浆挥发物与类似的不相容微量元素的比率，估计Holuhraun母体熔体的未脱气初级挥发物含量为1500-1700 ppm CO2，0.13-0.16 wt% H2O，60-80 ppm Cl，130-240 ppm F和500-800 ppm S。高密度流体包裹体表明，在压力>= 0.4 GPa（类似于12公里深度）时开始结晶，促进了CO2的深层脱气。在开始脱气之前，熔融CO2含量可能已达到3000-4000 ppm，总岩浆CO2预算估计为23-55 Mt。SO2释放开始于0.12 GPa（类似于3.6 km深度），最终导致SO2蒸气被包裹在低密度流体包裹体中。我们计算的同喷发挥发性释放为22.2吨的岩浆H2O，5.9-7.7吨CO2，和11.3吨的SO2的喷发过程中，F和Cl的释放是微不足道的。熔体夹杂物的限制，同步喷发挥发性物质的释放是类似的估计，在现场监测期间，除了H2O，现场测量可能会严重偏置的纳入大气降水。
The mass of volatiles emitted during volcanic eruptions is often estimated by comparing the volatile contents of undegassed melt inclusions, trapped in crystals at an early stage of magmatic evolution, with that of the degassed matrix glass. Here we present detailed characterisation of magmatic volatiles (H2O, - CO2, S, Fl and Cl) of crystal-hosted melt and fluid inclusions from the 2014-2015 Holuhraun eruption of the Baroarbunga volcanic system, Iceland. Based on the ratios of magmatic volatiles to similarly incompatible trace elements, the undegassed primary volatile contents of the Holuhraun parental melt are estimated at 1500-1700 ppm CO2, 0.13-0.16 wt% H2O, 60-80 ppm Cl, 130-240 ppm F and 500-800 ppm S. High-density fluid inclusions indicate onset of crystallisation at pressures >= 0.4 GPa (similar to 12 km depth) promoting deep degassing of CO2. Prior to the onset of degassing, the melt CO2 content may have reached 3000-4000 ppm, with the total magmatic CO2 budget estimated at 23-55 Mt. SO2 release commenced at 0.12 GPa (similar to 3.6 km depth), eventually leading to entrapment of SO2 vapour in low-density fluid inclusions. We calculate the syn-eruptive volatile release as 22.2 Mt of magmatic H2O, 5.9-7.7 Mt CO2, and 11.3 Mt of SO2 over the course of the eruption; F and Cl release were insignificant. Melt inclusion constraints on syn-eruptive volatile release are similar to estimates made during in situ field monitoring, with the exception of H2O, where field measurements may be heavily biased by the incorporation of meteoric water.