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以Helgeson等(1978)的热化学数据为基础,几个相还未得到的数据可从MgO-Al_2O_3-SiO_2、CaO-MgO-Al_2O_3-SiO_2、CaO-MgO-FeO-SiO_2、透辉石-硬玉-石英、尖晶石-橄榄石、黑云母-石榴石及单斜辉石-石榴石体系实验相平衡关系中计算取得.利用这些数据,可在一个广泛的压力(达50kb)和温度(达1500℃)范围内,计算含有地慢岩及二辉橄榄岩成分的CaO-MgO-Al_2O_3-FeO-Na_2O-SiO_2体系中的矿物组合(包括共生相的数量和成分).以图解法表示了辉石中Al_2O_3、单斜辉石中的Ca和与石榴石-单斜辉石分配系数(Fe~(2+)-Mg)相关的压力-温度的等值线(等成分线).在一定温度下,含有斜长石的基性岩转变为尖晶石橄榄岩的相变压力,以及尖晶石橄榄岩转变为石榴石橄榄岩的相变压力,分别在4-10及9-25kb范围内.
Based on the thermochemical data of Helgeson et al. (1978), data not available for several phases can be obtained from MgO-Al 2 O 3 -SiO 2, CaO-MgO-Al 2 O 3 -SiO 2, CaO-MgO-FeO-SiO 2, - Quartz, spinel - olivine, biotite - garnet and clinopyroxene - garnet system using these experimental data obtained in a wide range of pressures (up to 50kb) and temperature (Including the number and composition of intergrowth phases) in the CaO-MgO-Al 2 O 3 -FeO-Na 2 O-SiO 2 system, which contains the components of slow and lherzolites. Al 2 O 3 in the rock, Ca in the clinopyroxene, and the pressure-temperature contour (equi-component line) related to the garnet-clinopyroxene distribution coefficient (Fe 2 Mg) , The phase transition pressure of the basic rocks containing plagioclase into spinel peridotite and the phase transition pressure of spinel peridotite into garnet peridotite are respectively in the range of 4-10 and 9-25kb .