PICRITIC GLASSES FROM HAWAII

被引:113
作者
CLAGUE, DA [1 ]
WEBER, WS [1 ]
DIXON, JE [1 ]
机构
[1] CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125
关键词
D O I
10.1038/353553a0
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
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.
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页码:553 / 556
页数:4
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