耿马一带古近纪花岗岩类岩浆成因及演化

从地质学、岩石学、岩石地球化学等方面，探讨耿马一带古近纪岩浆岩类成因类型和演化、形成的构造背景及其地球动力学。侵入于红色建造K1n及河湖相Em中，比三叠纪花岗岩更偏基性，地球化学特征显示同时具同碰撞及火山弧花岗岩性质。下地壳的拆沉作用，地壳加厚及陆内造山驱动力的影响，富铁超镁铁质堆晶体拆沉于地幔中。堆晶体发生部分熔融，拆沉物熔融岩浆与地壳熔融岩浆于地壳岩浆房产生完全混合作用，形成古近纪具同碰撞及弧火山属性的岩浆。这种混合岩浆上升运移，产生较强的分离结晶作用，多次脉动定位形成古近纪不同岩性单元花岗岩。结合同位素测年结果及其它地质事件，确定其于古近纪侵入于陆内，是陆内造山晚期导致拆沉作用的产物。

THE GENESIS,EVOLUTION AND STRUCTURAL SETTING OF PALAEOGENE GRANITOID MAGMA IN GENGMA

The genesis type, evolution, structural setting and geodynamic characteristics of Palaeogene magmatic rocks in Gengma are discussed according to the study of their geological, petrographic and geochemic characteristics.They intrude into the red formation K_1n and river-lake facies Em, which are more basic than the Triassic granite and show characteristics of syncollision and volcanic arc granite. The crust thickening and inland orogenic force cause the ultramafic accumulative crystal to detach and sink in the mantle, which is partly melted. The magma of melted detaching and sinking crystal completely mixes with that of the melted crust in the magmatic chamber of crust, which forms the Palaeogene syncollision and volcanic arc magma. In the rising process, the separate crystallization of this mixed magma takes place and the Palaeogene granite unit with different lithologic characteris formed by many times of pulse emplacement. According to the isotope dating and other geological events, we think it is formed by the process resulting the detaching and sinking in inland during late orogenic stage and its intrusion period is Palaeogene.