Ultramafic rock fragments , which almost is altered to ophite , distributed in structural zone and displayed structural lens . so far , 9 fragments were discovered and mapped in nujinshan and bujing area ultramafic rock can be divided two kinds according to it ' s geochemical characteristics . one can be correlated with metaperidotite , which represented residual part that primary pyrolite underwent moderate partial melting , from some representative ophiolite melange in the world 按超镁铁岩类的地球化学特征可将其划分为两类：一类具有较高而稳定的mgo 、较低的al _ 2o _ 3 、极低的cao ， m f值为8 . 0 ? 8 . 4 ，按标准矿物组合进行分类可定为方辉橄榄岩，且均为fa _ ( 100 ) 、 en _ ( 100 )的镁质端元组分；可与世界上一些典型的蛇绿岩套中变质橄榄岩进行对比，代表了原始地幔中等部分熔融作用后残余物。
