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以大别山东部碧溪岭超高压变质榴辉岩为实验样品,使用活塞圆筒式高温高压装置,在1.5～3.0GPa,800～950℃下进行封闭体系的脱水熔融实验.结果表明:(1)1.5～2.0GPa下,含5%多硅白云母榴辉岩的初始熔融温度(Tm)≤800～850℃,熔融形成比例为3%的花岗质熔体;(2)随着温度和压力变化,榴辉岩中多硅白云母脱水熔融形成不同反应产物.1.5～2.0GPa和800～850℃下,多硅白云母和黝帘石在亚固相下析出流体使岩石部分熔融,蓝晶石形成斜长石反应边;(3)随着温度升高,多硅白云母与绿辉石、石英发生熔融反应,形成更长石、蓝晶石和熔体,更长石是多硅白云母在榴辉岩中主要的脱水熔融反应产物;(4)1.5～3.0GPa,≥900℃的脱水熔融反应形成镁铝榴石分子较高(37.67%～45.94%)的新生石榴石;在2.4～3.0GPa,≥900℃下,反应产物中形成钾长石和硬玉,代表反应体系处于更高压力下的流体不饱和状态.实验初步约束了1.5～3.0GPa下多硅白云母榴辉岩的脱水熔融固相线.将实验结果与大别-苏鲁地区超高压榴辉岩的部分熔融特征相结合,推断大别-苏鲁多硅白云母榴辉岩在折返过程中发生脱水熔融的压力和温度区间应为1.5～2.0GPa,800～850℃,并指示超高压榴辉岩在不同变质相转变过程中可能经历了流体活动性明显不同的部分熔融过程.
The dehydration and melting experiments of the closed system were carried out at 1.5 ~ 3.0GPa and 800 ~ 950 ℃ using the piston cylinder high-temperature and high-pressure device with the Bixi Ling UHPM metamorphic eclogite in the eastern part of the Dabie Mountains as the experimental sample.The results showed that: (1) At 1.5 ~ 2.0GPa, the initial melting temperature (Tm) of 5% phengite eclogites ≤ 800 ~ 850 ℃, and the granite melt formed at the rate of 3%. (2) With the temperature and pressure , The reaction products of polysilicone in the eclogite dehydrate and melt to form different reaction products.The polycrystalline muscovite and zoisite are precipitated at the subsolidus temperature of 1.5 ~ 2.0GPa and 800 ~ 850 ℃, The formation of plagioclase reaction side of the stone; (3) With the temperature increases, polysilicone and omphacite, quartz melting reaction, the formation of feldspar, kyanite and melt, the longer the stone is polysilicone (4) 1.5 ~ 3.0GPa, ≥900 ℃ dehydration melting reaction to form a higher purity (37.67% ~ 45.94%) of fresh garnet garnet; in the 2.4 ~ 3.0GPa, ≥900 ℃, the formation of potassium feldspar and jadeite reaction products, representing the reaction system is under higher pressure in the fluid unsaturated state experiment Step constraint of the dehydration melting solidus of the pliocene dolomite at 1.5 ~ 3.0GPa.The experimental results are combined with the partial melting characteristics of the ultrahigh-pressure eclogite in the Dabie-Sulu region to infer that the Dabie-Sulu The pressure and temperature range of dendritic melting of eclogite from eclogite should be 1.5 ~ 2.0GPa and 800 ~ 850 ℃, indicating that the ultrahigh-pressure eclogites may have undergone fluid activities during different metamorphic facies transitions The distinctly different part of the melting process.