法国中央高原Margeride花岗岩中黑云母岩的起源探讨

法国中央高原Ｍａｒｇｅｒｉｄｅ花岗岩暗色相中包含的Ａｎｃｅ和Ｖａｚｅｉｌｌｅｓ黑云母岩，大小达数十米，分别含有４０％和９０％以上的黑云母及少量的磷灰石、锆石、斜长石或钾长石，且发现有变质岩包体。野外观察可见，黑云母岩与其上覆花岗岩呈逐渐过渡关系，而其下部界限则很分明；它的面状及线状结构与相邻花岗岩的一致。矿物成分显示，各矿物（黑云母、斜长石、磷灰石）的化学成分与相邻花岗岩中相同矿物的相似或相同。由

STUDY ON ORIGIN OF BIOTITITE IN GRANITE OF MARGERIDE IN CENTRAL MASSIF,FRANCE

The biotitites of Ance and Vazeilles are included in dack factes of finite of Margeride in cental massif of France,their size are of about ten meters. They contain more than 40% and 90% biotite,respectively,and a few of Plagioclase,potasic feldspath, apotite and zircon. Some enclaves of metamorphic rocha are observed in biotitites. From the observations of field, we found that the contact relation between biotite and granite above is progressif ,but that between biotitite and granite below is below is abrupt. The Planair and linear stature of biotitite is consistent with that of associated granite. The chemical compositions of minerals (biotite, Plagioclase, apatite) of biotihte is similar of showing no difference to that of neighbouring granite. The temperature of formation of biotite estimated from T1 content of biotite is about 1 123 K,this is consistent with the temperature of intrusion of granitic magma of Margeride. All evidences indicate that the biotihtes in dark facies of granite of Margeride are a cumulat of biotite crystallized early, which formal at first nodule by(001 )Piling of biotite crystal and then cedimented in magma because of gravitational differentiation caused by difference in density between biotite nodule and granitic magma.