蓬莱与宽甸新生代碱性玄武岩及其深源包体和巨晶矿物的稀土元素  

BEE Geochemistry of Alkali Basalts and Their Ultramafic Inclusions and Megacryst Minerals from Kitandian and Fenglai

作　　者：殷纯嘏[1] 臧启家 

机构地区：[1]北京大学地质学系

出　　处：《北京大学学报（自然科学版）》1989年第2期235-242,共8页Acta Scientiarum Naturalium Universitatis Pekinensis

摘　　要：本文应用现代仪器分析方法——质谱同位素稀释法测定了辽宁宽甸和山东蓬莱碱性玄武岩及其深源超镁铁岩包体和巨晶矿物中的稀土元素REE,测定结果用Nakamura数值进行了球粒陨石标准化计算。根据所得REE丰度和分布模式特征,推测了两地区的尖晶石二辉橄榄岩属残渣型地幔岩包体,榴辉岩属原始型地幔岩包体。两地区的镁铝榴石巨晶可能是早期液相线上的产物,后期的变质作用对整个REE没有明显的影响。富铝普通辉石巨晶则是比镁铝榴石较晚期的结晶产物。两地区的碱性玄武岩及其超镁陕岩包体和巨晶矿物在REE丰度和分布模式上十分相似,表明了两地区所处的大地地质构造以及熔融和分异作用的物理化学条件的相似性。In this paper, A method of modern instrument analysis-mass spectremetric isotope dilution has been used for the determinations of REE in the samples of cenozoic alkali basalts and their ultramafic inclusions and megacryst minerals from Kuandian, Liaoning Provence, and Penglai, Shandong Provence. The diagrams of normalized REE patterns, calculated and plotted using Nakamura's chondrite values, show that the REE abundances and patterns of the Samples from Penglai are very similar to those from Kuandian. This uniformity arises from similar geologic structures and physico-chemical condi-tioiis of melting and fractional crystallization processes of these two areas. On the basis of REE patterns the spinel Iherzolites and the eclogites in the two areas have been considered as ultramafic inclusions of primary phases and residual phases respectively. The pyropes as megacryst may be earlier products from liquidus and the later metam-orphism has not led to redistribution of REE. The crystallization of the Al-rich augites may have occured later than that of the pyropes.

关 键 词：玄武岩 深源包体 巨晶矿物 REE 

分 类 号：P571[天文地球—矿物学]