【摘要】 <正> 我国东部与南部新生代碱性玄武岩及火山角砾岩喷发过程中,携带了来自地幔及玄武岩浆深部结晶分异形成的包体,这些包体包括尖晶石二辉橄榄岩、石榴石二辉橄榄岩、辉石岩和辉长岩类,以及石榴石、辉石和歪长石巨晶等。我们收集了福建、江苏、河北及云南等地数十个包体,并对其中13个包体的矿物进行了研究,计算了包体形成的温度和压力,并讨论了成因。更多还原

【Abstract】 Ten spinel-lherzolite xenoliths and one olivine-pyroxenolite xenolith, which were collected from Fujian, Jiangsu, Hebei, and Yunnan province, consist of olivine (Fo_87.7-91.2), enstatite(En_87.3-89.7),Cr-diopside and spinel. According to the Mg/(Mg+Fe²⁺)ratios for the rocks and their mineralogies, they belong to Cr-diopside type. The websterite is composed of bronzite (En_71.9) and augite, while the gabbro-norite consists of hypersthene(En_68.9)and augite, belonging to Al-augite type.The geothermos of spinel-lherzolites were calculated by four methods, giving a temperature range of 925—1,072℃. However, according to P.R.A. Wells’s the temperature ranges from 845 to 1,014℃, and by D.H.Lindsly’s approach, from 716 to 974℃. The pressure of them ranges from 15.1 to 19.8 kb.Genetically, the spinel-lherzolites and the olivine pyroxenlite are thought to have been derived from the residual mantle material by partial melting at approximately 1,000℃ and at a depth of about 50—70 km. The websteite and gabbro-norite may be products of the crystallization-differentiation of alkali basaltic magma.更多还原