论文部分内容阅读
超高压条件下辉石溶入石榴石使石榴石出现Si~Ⅵ+M~Ⅵ=Al~Ⅵ+Al~Ⅵ和Si~Ⅵ+Na~Ⅷ=Al~Ⅵ+M~Ⅷ偶合置换而形成超硅石榴石,其程度随压力增高而增强.超硅石榴石以及在减压过程中石榴石出溶辉石、金红石、磷灰石和石英的现象已在天然岩石中发现,在幔源岩石以及与板块深俯冲有关的超高压变质作用研究方面具有重要的意义.Ti通过对Si的置换、P通过P~Ⅳ+Na~Ⅷ=Si~Ⅳ+Ca~Ⅷ偶合置换、K通过Si~Ⅵ+K~Ⅷ=Al~Ⅵ+M~Ⅷ偶合置换、水通过[(OH)_4]~(4-)=[SiO_4]~(4-)置换即[4H]~(4+)=Si~(4+)置换进入石榴石晶格.单斜辉石中的Eskola辉石组分M_(0.5)AlSi_2O_6可能与一般辉石组分M_2Si_2O_6在超高压条件下一道进入石榴石,将在石榴石中出现出Si~Ⅵ+0.5□~Ⅷ=Al~Ⅵ+0.5M~Ⅷ偶合置换.这种偶合置换的存在是导致金红石、磷灰石和石英在石榴石中出溶的关键.根据这一新的偶合置换,本文给出了两个新的分解反应,作为这些矿物在石榴石中出溶的理论模型.实际的出溶可以是多个分解反应的联合.
Under the condition of high pressure, pyroxene dissolves into garnet to make the garnet appear Si ~ Ⅵ + M ~ Ⅵ = Al ~ Ⅵ + Al ~ Ⅵ and Si ~ Ⅵ + Na ~ Ⅷ = Al ~ Ⅵ + M ~ Silicon garnet, the extent of which increases with increasing pressure.Some phenomena of ultra-silicon garnet and the garnet pyroxene, rutile, apatite and quartz during depressurization have been found in natural rocks, and in mantle-derived rocks and It is of great significance to study ultrahigh-pressure metamorphism related to the deep subduction of the plate, in which Ti is replaced by Si by P ~ Ⅳ + Na ~ Ⅷ = Si ~ Ⅳ + Ca ~ K ~ Ⅷ = Al ~ Ⅵ + M ~ Ⅷ coupling replacement, water through the [(OH) _4] ~ (4 -) = [SiO_4] ~ 4+) into the garnet lattice.The Eskola pyroxene M_ (0.5) AlSi_2O_6 in clinopyroxene probably enters the garnet together with the general pyroxene component M_2Si_2O_6 under ultrahigh pressure and will appear in the garnet The coupling of Si ~ Ⅵ + 0.5 □ ~ Ⅷ = Al ~ Ⅵ + 0.5M ~ Ⅷ is the key to the dissolution of rutile, apatite and quartz in garnet.According to this new Coupling replacement, this article gives two new decomposition reaction, Theoretical models of these minerals in the garnet soluble. The actual dissolution may be a plurality of combined reactions of decomposition.