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中缅边界那邦麻粒岩相变质基性岩地球化学特征研究表明其原岩是岩浆岩 ,并具有 MORB的特性 ,其岩石化学具有以下特征 :岩石的 TFe O/ Mg O值低 (1.10～ 2 .17) ,AFM图解上显示拉斑玄武岩演化趋势 ;Ti O2 含量 (1.14%～ 1.81% )高于岛弧拉斑玄武岩。多数微量元素与大洋中脊拉斑玄武岩含量相当 ,Nd、Ta值高于岛弧拉斑玄武岩。稀土元素配分图显示轻稀土亏损、重稀土较有富集的配分型式 ,稀土元素和总量 (ΣREE)值十倍于球粒陨石 (2 4～ 5 0μg/ g) ,(L a/ Sm ) N=0 .43～ 0 .75 ,(L a/ Yb) N=0 .45～ 0 .74,87Sr/ 86 Sr=0 .70 4～ 0 .70 5 ,1 4 3Nd/ 1 4 4 Nd=0 .5 12 9～ 0 .5 132 ,εNd=+4 .85～ +9.6 7。大地构造背景和年代学研究显示 ,那邦变质基性岩是先前密支那新特提斯洋壳的上部组成 ,是俯冲板片裂离作用折返地表的麻粒岩相岩石 ,对探讨特提斯洋俯冲时限、俯冲洋壳的变质变形作用、俯冲物质的深部运动等都有重要的意义
The geochemical characteristics of granulite facies metamorphic metamorphic rocks in Nambang area on the Sino-Burmese boundary indicate that the protoliths are magmatic rocks and have the characteristics of MORB. The petrochemical characteristics of the rocks are as follows: the value of TFe O / Mg O is low (1.10 ~ 2.17). The AFM diagram shows the evolution trend of tholei basalts. The Ti O2 content (1.14% -1.81%) is higher than that of island arc tholeiites. Most trace elements and mid-ocean ridge tholeigenic basalt content, Nd, Ta value higher than the island arc tholeigenic basalt. The rare earth elements distribution diagram shows the depletion of light rare earths and the distribution pattern of heavy rare earths more enriched. The values of rare earth elements and total ΣREE are ten times higher than that of chondrules (2-4 ~ 50μg / g), (L a / Sm) N = 0 .43 to 0.75, (L a / Yb) N = 0.45 to 0.74, 87 Sr / 86 Sr = 0.70 4 to 0.70 5, 1 4 3 Nd / 1 4 4 Nd = 0 .5 12 9 ~0 .5 132, εNd = +4 .85 ~ +9.6 7. Geotectonic background and chronological studies show that the Nambong metamorphic basement is an upper part of the previously Neotropical Tethyan oceanic crust in the Myitkyla, The time of oceanic subduction, the metamorphism and deformation of subducted oceanic crust and the deep movement of subducted matter all have important significance