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大别山太湖县石马超高压榴辉岩相岩石可分为两类:(1)以柯石英榴辉岩(已退变质)为代表的硅饱和岩石;(2)以二矿物榴辉岩、石榴顽火辉石岩、含顽辉石榴子石岩、单辉橄榄岩、方辉橄榄岩为代表的硅不饱和岩石。前者的原岩是沉积火山碎屑岩;后者的原岩可能是地幔岩经高度部分熔融后的残余物,其后来受到高H2O和CO2流体的变化。本研究提供的有关这些超高压岩石及其围岩的岩矿特征以及温压计计算表明超高压榴辉岩相岩石曾经历从角闪岩相(627-699℃,14-23kbar)到柯石英或金刚石榴辉岩相(700-800℃,30-42kbar)再退变至角闪岩相(556-826℃,13-30kbar和一定的水压下)的顺时针P-T轨迹。
The ultrahigh-pressure eclogite facies rocks of Shima in Taihu County of the Dabie Mountains can be divided into two types: (1) silicon-saturated rocks represented by coesite eclogites (retrogressive metamorphism); (2) Pyroxene rock, enstatite garnet, hectorite, and harzburgite. The former protolith is volcaniclastic sedimentary; the latter protolith may be the residue of the mantle rock after partial melting, which is followed by changes of high H2O and CO2 fluids. The rock characteristics and the thermometer calculations of these ultrahigh-pressure rocks and their surrounding rocks provided by this study show that the ultrahigh-pressure eclogitic facies rocks have been experienced from amphibolite facies (627-699 ℃, 14-23kbar) to coesite Or diamond eclogite facies (700-800 ° C, 30-42 kbar) back to the clockwise PT trajectory of the amphibolite facies (556-826 ° C, 13-30 kbar and a certain water pressure).