海南岛蓬莱地区超镁铁岩包体及其寄主玄武岩的研究  

THE STUDY OF ULTRAMAFIC INCLUSIONS AND THEIR HOST EASALTS FROM PENGLAI IN HAINAN ISLAND

作　　者：付建明[1] 

机构地区：[1]地质科学院宜昌地质矿产研究所,宜昌443003

出　　处：《矿物岩石》1991年第4期22-32,共11页Mineralogy and Petrology

摘　　要：蓬莱地区寄主玄武岩为晚第三纪火山喷发的产物,主要岩石为碧玄岩,碱性橄榄玄武岩和橄榄玄武岩,其中含有超镁铁岩包体。寄主玄武岩属碱性系列,是地幔橄榄岩低度部分熔融的产物。超镁铁岩包体具有局部熔融的迹象和弱亏损型地幔岩的特征,推测为上地幔橄榄岩低度部分熔融后的难熔残余。Penglai body located in the west of Qiongbei(the north of Hainan Island)is of Cenozoic igneous rocks. The volcanic rocks are mainly cosisted of basanites, alkalic-olivine basalts and olivine basalts with ultramafic inclusions spinel Iherzolites. The host basalts in composition belong to the alkalic series and are characterized by higher CaO, K_2O +Na_2O, TiO_2 and P_2O_5, and lower SiO_2 and Al_2O. Except for enrichment of the incompatible elements, such as REE and LIEE, the host basalt have higher Al_2O_3/CaO ratios, with M value=60—72, and degree of melting=7％. All these features indicate that the host basalts are product of that the upper mantle peridotite partly melted in lower degree. The ultramafic inclusions in this region have signs of partial melting and characteristics of weakly depleted pyrolite. The calculated temperature and pressure for the lherzolites confined to 1056℃ and 2.1 GPa respectively. So it seems be that they are remains driven from the mantle peridotite. The ultramafic inclusions are rather rich in Fe, LILE and LREE, and have phenomena that phlogolites metasomatized olivine, showing the source phyolite had already been metasomatized by the mantle fluid-phases before partial melting.

关 键 词：超镁铁岩 包体 玄武岩 海南 

分 类 号：P588.125[天文地球—岩石学]