青藏高原北羌塘半岛湖新生代粗面玄武岩橄榄石电子探针和激光探针分析

LA-ICP-MS AND EMP ANALYSIS OF OLIVINES IN CENOZOIC TRACHYBASALT FROM NORTH QIANGTANG, QINGHAI-TIBET PLATEAU

利用电子探针和激光探针剥蚀系统 (LA ICP MS) ,对北羌塘新第三纪粗面玄武岩中的橄榄石主元素和微量、稀土元素进行了系统分析。结果表明 ,本区橄榄石Fo平均为 88,属贵橄榄石种属。相对富集Ni、Co和重稀土 ,而强烈亏损轻稀土及Rb、Sr、Ba、Zr等大离子亲石元素。其稀土元素配分型式与粗面玄武岩全岩稀土配分型式呈互补状态。

Based on the electron microprobe (EMP) and laser ablation inductively coupled plasma mass spectrometric (LA ICP MS) analyses, the major and trace element features of olivines from the Cenozoic trachybasalt in northern Qiangtang are discussed in this paper. The result indicates that all of the olivines belong to chrysolite. They exhibit Ni, Co and HREE enrichment but Rb, Sr, Ba, Zr, LREE depletion. Especially, the distribution patterns of the olivine and trachybasalt are compensating each other.