标题
大晶的形成在Migmatitic角闪岩从哈兰省,西南瑞典
教师的导师(s)
爱德华·汉森博士
文档类型
海报
事件日期
4-10-2015
文摘
大型矿物颗粒的增长(大晶)可以得到流体阶段,允许快速扩散。因此,大晶的存在在变质岩的一个指标的硅酸盐熔体或其他流体相在变质作用。我们研究了大晶角闪石(Hbl),石榴石(Grt),斜辉石(Cpx)和斜方辉石类(Opx)与tonalitic证据和黑素体镁铁质混合岩Stensjӧ自然保护区和周边地区Bjӧrkasjӧ湖。这两个地方都在东部的皮带Sveconorwegion造山带,哈兰省,瑞典。我们映射地方和偏光显微镜、能谱检验样品。我们做了改进算法在电子探针定量矿物分析。全岩分析是由x射线在Actlabs花期,安大略省。当主机岩石包含子+ Pl(斜长石)+ / - Cpx没有通或Bt(黑云母)大晶子或子+ Cpx。大晶的成分类似于母岩成分相同的矿物。斜长石在夹杂物周围,立即Cpx大晶可以包含多达46%的Ab(钠长石)比Pl远离大晶。 When the host rock contains Hbl+Pl+Grt+Cpx without biotite the megacrysts are either Grt or Cpx. When the host contains Hbl+Pl+Grt+Bt the megacrysts are Opx. These megacrysts are surrounded by a reaction rim of Hbl+Qtz+/-Cpx+/-Grt, and Hbl in the rims has distinctly lower Ti and K2O+Na2O concentrations than in the host. The anhydrous megacrysts, (Cpx, Opx, Grt), probably formed by vaporabsent (dehydration) melting. The different kinds of anhydrous megacrysts formed by different melting reactions controlled by the chemistry and mineralogy of the original rock. Hornblende megacrysts may have formed by the retrogression of Cpx during crystallization of the melt. Alternatively they may represent water-assisted melting, without partial melting, by a concentrated brine.
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这项研究是由密歇根空间格兰特财团的资助。