作　　者： ; ;

机构地区： 中山大学地球科学系地质系

出　　处： 《中山大学学报（自然科学版）》 1995年第3期95-101,共7页

摘　　要： 海南蓬莱地区的刚玉巨晶主要和新生代碱性玄武岩有关。刚玉巨晶表面具有明显熔蚀结构，内含锆石、铌钛铁矿等矿物及ＣＯ＿２流体熔融包裹体，包裹体均一温度为１１２５～１２６５℃，而且巨晶富含轻稀土元素，稀土分配模式与碱性玄武岩明显不同，而与伟晶岩型刚玉巨晶母岩─—紫苏花岗岩相似。认为刚玉巨晶形成于富含不相容元素和挥发份的环境，而非碱性玄武岩浆的结晶产物。巨晶的形成和玄武岩浆形成过程中，裂谷引起的地壳物质塌陷及其与超基性岩浆的同化混染、交代作用有关，系地壳与上地幔界面附近深部高压变质交代作用的产物。 Penglai of Hainan province is one of the important localities of sapphire in China.Thecorundum megacrysts ane related to Cenozoic alkali basalt and have the following features: hav-ing clear surface melted structure and containing Zircon&Tiniobite &CO_2-bearing fluid melt-ing inclusions with the homogeneous temperatures of 1125～1265℃,being rich in light REE andhaving the REE distribution pattern similar to that of hypersthene granite,mother rock of peg-matite-type corundum , but different from those alkali basalts.Based on the above-mentioneddata,the authors think the corundums were produced in the enviroment with rich incompatible el-ements & volatile components,not the result of crystallization of basaltic magama. The forma-tion of corundums may be related to the crust substances collapse resulted from rift and its assimi-lation & contamination and metasomatism with ultrabasic magama during the formation ofbasalts.The megacrysts are the result of metamorphism& metasomatism at high pressure near theboundary between the crust and the upper mantle。

关 键 词： 刚玉巨晶 成因 碱性 玄武岩 锆石 包裹体

领　　域： [天文地球] [天文地球]