Water content of granitic melts from Cornwall and Erzgebirge: A Raman spectroscopy study of melt inclusions
Water content of granitic melts from Cornwall and Erzgebirge: A Raman spectroscopy study of melt inclusions
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DOI：
10.1127/0935-1221/2006/0018-0429
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发表时间：
2006-07
影响因子：
2.1
通讯作者：
A. Müller;R. Thomas;M. Wiedenbeck;R. Seltmann;K. Breiter
中科院分区：
文献类型：
--
作者：
A. Müller;R. Thomas;M. Wiedenbeck;R. Seltmann;K. Breiter
采用拉曼光谱、二次离子质谱和电子探针等方法，对英国西南部Lands End岩体和德国东部Erzgebirge火山-深成杂岩中华力西晚期锡花岗岩的石英熔体包裹体进行了分析。使用在850°C和2kbar下操作24小时的冷密封高压釜将结晶的MI均质化。共焦拉曼光谱测定的陆末花岗岩均质化MI的H2O浓度范围在1.5和5.4wt.%之间。陆缘花岗岩中的几个MIs含有18.2 - 38.6wt.%的高盐流体这样的混合流体和硅酸盐-MIs是挥发分过饱和的岩浆的典型特征。硅酸盐玻璃/盐相的比值随花岗岩寄主分异程度的增加而减小。东厄尔士山脉的Niederbobritzsch花岗岩、Schonfeld流纹英安岩、Teplice流纹岩、Altenberg-Frauenstein微花岗岩和Schellerhau花岗岩的MI的H2O含量在0.7和11.9wt.%之间变化。来自火山岩的MI比来自花岗岩的MI具有更大的可变浓度。MI和整个岩石之间的高化学差异表明，在Schonfeld流纹英安岩的石英斑晶被注入到一个分层的岩浆房的过程中的多个补给事件在房的基地。从东部Erzgebirge花岗岩MI不包含高盐度流体，但他们有F浓度高达11.2重量%。通过西姆斯测定代表性均质化MI的Li、Be和B含量。尽管寄主岩石分馏程度不同，但每个岩浆岩省的MI轻亲石元素比值是恒定的。东部厄尔士山脉火山-深成杂岩岩石中的MI相对富集Li和Be，而Land's End岩体花岗岩中的MI具有较高的B含量。硅酸盐熔体的轻亲石元素的独特比例也反映在岩浆寄主石英的轻亲石元素比例上。
Melt inclusions (MIs) occurring in quartz of late-Variscan Sn-specialized granites from the Land's End pluton in SW England and from the eastern Erzgebirge volcano-plutonic complex in Germany were analyzed by Raman spectroscopy, secondary ion mass spectrometry and electron microprobe. Crystallized MIs were homogenized using cold-sealed autoclaves operating at 850°C and 2 kbar for 24 hours. The H2O concentration of homogenized MIs from the Land's End granites determined by confocal Ramanspectroscopyrangebetween1.5and5.4wt.%.SeveralMIsfromtheLand'sEndgranitescontainahypersalinefluidwith18.2 to38.6wt.%H2O.Such mixedfluidandsilicate-MIsare typical for magmasthat were oversaturatedinvolatiles. The ratioofsilicate glass/saline phase decreases with increasing degree of differentiation of the granite host. The H2O content of MIs from the Niederbobritzsch granite, Schonfeld rhyodacite, Teplice rhyolite, Altenberg-Frauenstein microgranite and Schellerhau granite inthe eastern Erzgebirge varies between 0.7 and 11.9 wt.%. The MIs from the volcanic rocks have more variable concentrations than the MIs from the granites. The high chemical discrepancies between MIs and whole rock suggest that the quartz phenocrysts in the Schonfeld rhyodacite were injected into a stratified magma chamber during the course of multiple recharge events at the chamber's base. MIs from granites from the eastern Erzgebirge do not contain hypersaline fluids, however they have F concentrations of up to 11.2 wt.%. The Li, Be and B contents of representative homogenized MIs were determined by SIMS. The light lithophile element ratios of MIs are constant for eachmagmatic province despite different fractionation degrees of the host rocks. MIs from rocks of the eastern Erzgebirge volcano-plutonic complexare relatively enriched in Li and Be, whereas MIs in granites of the Land's End pluton have higher B contents. The distinctive ratio of light lithophile elements of the silicate melt is also reflected in the light lithophile element ratio of the magmatic host quartz.