伊春地区晚奥陶世花岗质岩石中闪长质包体的成因

Genesis of dioritic inclusions in Late Ordovician granitic rocks in the Yichun area

在黑龙江省伊春地区笑山河林场一带,发育一套成分演化序列的晚奥陶世花岗岩体,通过系统的1∶5万区调工作,对其进行了详细的研究和划分,建立了北影林场序列的谱系填图单位,其笑山河单元细中粒似斑状含角闪石黑云母二长花岗岩中普遍发育闪长质包体,多呈大小不等的椭圆状分布于岩体边部。经对花岗质岩石和闪长质包体岩石学、矿物学、岩石地球化学等的详细研究发现,二者在成因上具联系性,演化上具亲缘性,闪长质包体是不混溶包体,是长英质岩浆发生融离不混溶作用时自身演化的结果。

A compositional evolu tionary series of Late Ordovician granite bodies is developed in the vicini-ty of the Xiaoshanhe Tree Farm in the Yichun area,Heilongjiang Province.Through systematic1:50000regional survey,the series has been studied and classi fied in detail and the hierarchical mapping units of the Beiying Tree Farm have been established.Dioritic inclusions are common in fine-to medium-grained, porphyritic hornblende-bearing biotite monzogranite of the Xiaoshanhe unit.Mo st of these inclu-sions occur as elliptical grains of varying size at the edges of the granite intrusions.Intensive petrological,mineralogical and rock geochemical studies of the granitic rocks and dioritic inclusions indicate th at the rocks and inclusions are genetically related and have an affinity in evo lution.The dioritic inclusions are im-miscible ones and resulted from the evo lution of the felsic magma during its liquation.