• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Volcanology and Geothermal Research >Barometry of lavas from the 1951 eruption of Fogo, Cape Verde Islands: Implications for historic and prehistoric magma plumbing systems
【24h】

Barometry of lavas from the 1951 eruption of Fogo, Cape Verde Islands: Implications for historic and prehistoric magma plumbing systems

机译：1951年佛得角群岛福戈火山喷发产生的熔岩气压：对历史和史前岩浆管道系统的影响

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Fogo is one of the most active oceanic volcanoes in the world. The island was affected by a prehistoric giant lateral collapse that decapitated the summit of the former Monte Amarelo volcano. Subsequent volcanism has partly filled the collapse scar and built up the present-day Cha das Caldeiras plain and the Pico do Fogo stratovolcano. We have conducted a thermobarometric study of historic and prehistoric, basanitic to tephritic rocks in order to gain insight into Fogo's magma plumbing system and the impact of the collapse event on fractionation depths. A main focus was the penultimate 1951 eruption, which produced basanites to tephrites (5.0-8.2 wt.% MgO) at two sites south and northwest of Pico do Fogo. Clinopyroxene-melt barometry of phe-nocrysts yields a well-confined pressure range of 480-650 MPa for the final crystallization level. Microther-mometric data of CO_2-dominated fluid inclusions in olivine and clinopyroxene phenocrysts yield systematically lower pressures of 250-430 MPa. Inclusions in cumulate xenoliths yield pressures of 100-290 MPa. The combined data indicate pre-eruptive magma storage in the uppermost mantle between 17 and 22 km depth and syn-eruptive short-term magma stalling within the lower crust at 8-13 km depth. The lower pressures revealed by fluid inclusions in xenoliths may indicate that they originate from pre-1951 magma pulses that stalled and crystallized at variable levels in the crust. There is, however, no petrolog-ic evidence for persistent crustal magma chambers. Clinopyroxene-melt barometric data of other historic and prehistoric eruptions indicate that magma storage and differentiation occurred in the uppermost mantle at pressures between 420 and 870 MPa (15-30 km depth) throughout the subaerial evolution of Fogo. Our data indicate that fractionation depths decreased significantly during a period of about 100 ka representing a strong growth phase of Fogo edifice leading up to the giant Monte Amarelo flank collapse at 123-62 ka. This trend seems to have been interrupted by the flank collapse, as early post-collapse magmas stagnated at deeper levels than late pre-collapse ones. Historic eruptions show shallower and broader pressure ranges, indicating an increase in complexity of the magma storage systems. Thus petrologic data indicate that flank collapse events may significantly influence deep-seated magma plumbing systems beneath ocean islands.
机译：Fogo是世界上最活跃的海洋火山之一。该岛受到史前巨型横向倒塌的影响，该倒塌使前蒙特阿马洛洛火山的山顶斩首。随后的火山活动部分填补了坍塌的疤痕，并建立了如今的Cha das Caldeiras平原和Pico do Fogo层状火山。为了对福戈的岩浆管道系统以及崩塌事件对分馏深度的影响有深入的了解，我们对历史和史前，玄武质至特发性岩石进行了热压法研究。一个主要的焦点是1951年倒数第二次喷发，在皮科杜福戈以南和西北两个地点将重铁矿生成为软铁矿（5.0-8.2 wt。％MgO）。菲·诺氏体的斜茂铁熔体气压计可为最终结晶水平提供480-650 MPa的有限压力范围。橄榄石和斜辉石型酚醛树脂中CO_2为主的流体包裹体的显微测温数据可系统地产生较低的250-430 MPa压力。累积的异种岩中的夹杂物产生的压力为100-290 MPa。合并的数据表明，喷发前岩浆在17至22 km深度之间的最高地幔中储藏，并且喷发时短期岩浆在8-13 km深度的下地壳内停滞。异种岩中流体包裹体揭示的较低压力可能表明它们源自1951年以前的岩浆脉冲，该脉冲在地壳中以不同水平失速并结晶。但是，没有岩石学证据表明存在持续的地壳岩浆室。其他历史和史前喷发的斜辉石融化的气压数据表明，在整个Fogo的亚空中演化过程中，岩浆的储集和分化发生在最高地幔中，压力在420至870 MPa（深度15-30 km）之间。我们的数据表明，在约100 ka的时间内，分馏深度显着下降，这代表了Fogo大厦的强大生长期，导致123-62 ka巨型Monte Amarelo侧面崩塌。这种趋势似乎已被侧面崩塌打断，因为崩塌后的早期岩浆比崩塌前的晚期岩浆停滞在更深的水平。历史性火山喷发显示压力范围越来越浅，表明岩浆储存系统的复杂性增加。因此，岩石学数据表明，侧倾塌陷事件可能会严重影响大洋洲下方的深部岩浆管道系统。

著录项

相似文献

  • 外文文献
  • 中文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号