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华北克拉通麻粒岩的SiO2 含量分布具有明显的双峰式分布特征 ,两个峰值区间分别为 4 0 %～ 57% (峰值为 51 % )和 57%～ 78% (峰值为 67% ) ,但Mg#较集中 ,主体分布范围为 4 0 %～ 52 % ,Mg#和SiO2 之间的相关性较差。各类麻粒岩地球化学组成具有强烈的U、Th亏损和不同程度的Ba、Sr富集特征。另外 ,中、酸性麻粒岩Nb、Ta强烈亏损并发生明显的分异作用 ,Nb/Ta平均比值高达 3 1 .71～ 3 6.56,基性麻粒岩则表现出Rb亏损而Ta富集的特征 ,Nb/Ta平均比值仅为 1 7.2 0。各类麻粒岩的Eu/Eu (Tb) 与Mg#无关 ,主体大于 1。与世界范围内的同类太古宙麻粒岩相比 ,华北克拉通麻粒岩产热元素U、Th平均含量远远低于世界平均值 ,稀土元素平均含量普遍较低 ,但具有较高的Sm/Nd比值 ,而且酸性麻粒岩的SiO2 含量也明显偏低
The distribution of SiO2 in North China carat granulite has obvious bimodal distribution with 40% -57% (peak value 51%) and 57% -78% (peak value 67%) of the two peak values, respectively. However, Mg # is more concentrated with the distribution range of 40% ~ 52%, and the correlation between Mg # and SiO2 is poor. Various types of granulite geochemical composition has a strong U, Th loss and varying degrees of Ba, Sr enrichment characteristics. In addition, the acidic granulites Nb and Ta are strongly depleted and distinctly differentiated, with an average Nb / Ta ratio as high as 31.76 to 3.5656, while the basic granulites show Rb depletion and Ta enrichment The average ratio of Nb / Ta is only 1 7.2 0. All kinds of granulite Eu / Eu (Tb) and Mg # have nothing to do, the main body is greater than 1. Compared with the same kind of Archean granulites in the world, the average U and Th contents of the nodular granulites in North China are far below the world average, while the average content of rare earth elements is generally low, but the Sm / Nd ratio, and the SiO2 content of acidic granulite is also significantly lower