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在法国比利牛斯阿格里(Agly)地块深变质片麻岩中产有海西期紫苏花岗岩.利用石榴石和黑云母之间的Fe—Mg分配(K_D)估计了它的热历史.虽然这些矿物有着下同的成因,但是在紫苏花岗岩和围岩片麻岩中它们有相类似的成分.在紫苏花岗岩中黑云母—石榴石矿物对是斜方辉石蚀变的退变产物.斜长石与斜方辉石的反应可写成:斜方辉石+斜长石+流体1(H_2O+A1+K+Fe+Ti)=黑云母+石榴石+石英+流体2(H_2O+Na).石榴石相对贫钙(4—2.5%钙铝榴石);在片麻岩中的石榴石是自形和环带状的,而在紫苏花岗岩中是变嵌晶状的;两种类型都显示有Fe、Mn增加,Mg降低的退化边缘(数百微米宽).黑云母八面体位置上的阳离子(Ti~(4+)+Fe~(2+)和(Mg~(2+)+Al_(VI)~(3+)之间显示有良好的相关关系.Ti和Fe增加,而Mg和Al_vI降低.在Fe~(2+)和Mg~(2+)之间,有一个反线性相关关系,
Hercynian perillas are found in the deep metamorphic gneiss in the Agly block of the French Pyrene, and its thermal history is estimated using the Fe-Mg distribution (K_D) between garnet and biotite. Although these minerals have the same genesis, they have similar compositions in peridotite and surrounding gneisses, and the biotite-garnet mineral pairs in peridotite are degenerated by orthopyroxene The reaction of plagioclase with orthopyroxene can be written as orthopyroxene + plagioclase + fluid 1 (H 2 O + Al + K + Fe + Ti) = biotite + garnet + quartz + fluid 2 (H 2 O + Na). Garnet is relatively poor in calcium (4-2.5%) and the garnet in gneiss is self-forming and ring-shaped, while in perilla granite it is crystalline. Both types show the degenerated edges (hundreds of microns wide) with increased Fe, Mn, and decreased Mg.Cations (Ti ~ (4 +) + Fe ~ (2+) and (Mg ~ 2 +) + Al_ (VI) ~ (3 +) .Ti and Fe increased, while Mg and Al_vI decreased.At between Fe ~ (2+) and Mg ~ (2+) There is an inverse linear relationship,