韧性剪切带糜棱岩类质量平衡分析——以豫西秦岭群蛇尾剪切带为例

蛇尾剪切带中糜棱岩的质量平衡分析表明:(1)以Al_2O_3守恒为限制条件,该剪切带损失了10％土的质量和体积,糜棱岩类有Na_2O,Zr,Sr的获得;SiO_2,TiO_2,FeO,Fe_2O_3,MgO,MnO,CaO,K_2O及Co,Ni,V,Cr,Cu,Y则损失了;(2)从初糜棱岩-糜棱岩,初糜棱岩-超糜棱岩和糜棱岩-超糜棱岩得出的质量等比线显示,糜棱岩类之间没有明显的质量和体积损失。糜棱岩组分的得失主要发生在初糜棱岩阶段,同初糜棱岩相比,糜棱岩、超糜棱岩有CaO的获得,FeO,MgO,TiO_2,Cr,Co,V,Y微弱的获得,Na_2O则有轻微的损失。

MASS BALANCE ANALYSIS OF MYLONITES IN DUCTILE SHEAR ZONE : A CASE STUDY OF SHEWEI SHEAR ZONE IN QINLING GROUP, WESTERN HENAN

The results of mass balance analysis on the mylonites from Shewei shear zone are as follows; (1 )Shewei shear zone lost 10% of mass and volume as A12O3 is assumed to be constant. The mylonites have a gain of Na2O . Zr, Sr, and loss of SiO2, TiO2. FeO, Fe2O3, MgO, MnO, CaO, K2O, Co, Ni, V , Cr, Cu and Y. (2) Isocons determined by protomylonite vs. mylonite, protomylonite vs. ultramylonite, and mylonite vs. ultramylonite show that there are no distinct loss and gain of mass and volume among them. The gain and loss of components occurred mainly in the protomylonitic stage. Mylonite and ultramylonite have a gain of CaO greatly, and FeO, MgO . TiO2. Cr, Co, V . Y slightly, and a loss of Na2O as compared with the protomylonite.