PICRITIC GLASSES FROM HAWAII
PICRITIC GLASSES FROM HAWAII
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DOI：
10.1038/353553a0
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发表时间：
1991-10-10
期刊：
影响因子：
64.8
通讯作者：
DIXON, JE
中科院分区：
文献类型：
--
作者：
CLAGUE, DA;WEBER, WS;DIXON, JE
原始夏威夷拉斑玄武岩熔体的 MgO 含量估计范围为 8 wt% 至高达 25 wt%（参考文献 1、2）。 一般来说，这些估计来自对熔岩全岩成分的分析，再加上观察到的大多数镁橄榄石斑晶的成分。 但对岩浆成分的最佳估计来自火山玻璃，因为它代表了淬火时的液体成分；淬火过程中发生的变化很小。 在这里，我们报告了在基拉韦厄火山近海发现的拉斑玄武岩玻璃的发现，其中含有高达 15.0 wt% 的 MgO。 据我们所知，这些是迄今为止发现的氧化镁含量最高的玻璃，并且具有最高的喷发温度（约 1,316 摄氏度）。 这些苦味质（高MgO）液体的存在对上地幔的温度结构、岩浆输送以及夏威夷火山的物质和热预算产生了限制。 此外，苦味铁矿熔体受岩浆储层过程的影响很小，因此可以相对直接地推断出原始熔体的成分及其挥发物含量。
ESTIMATES of the MgO content of primary Hawaiian tholeiitic melts range from 8 wt% to as high as 25 wt% (refs 1, 2). In general, these estimates are derived from analysis of the whole-rock composition of lavas, coupled with the compositions of the most magnesian olivine phenocrysts observed. But the best estimate of magma composition comes from volcanic glass, as it represents the liquid composition at the time of quenching; minimal changes occur during the quenching process. Here we report the discovery of tholeiitic basalt glasses, recovered offshore of Kilauea volcano, that contain up to 15.0 wt% MgO. To our knowledge, these are the most magnesian glasses, and have the highest eruption temperatures (approximately 1,316-degrees-C), yet found. The existence of these picritic (high-MgO) liquids provides constraints on the temperature structure of the upper mantle, magma transport and the material and thermal budgets of the Hawaiian volcanoes. Furthermore, picritic melts are affected little by magma-reservoir processes, and it is therefore relatively straightforward to extrapolate back to the composition of the primary melt and its volatile contents.