中子活化分析法研究达拉布特蛇绿岩中超镁铁质岩的地球化学特征

STUDY ON GEOCHEMICAL CHARACTERISTICS OF ULTRAMAFIC ROCKS FROM DALABUTE OPHIOLITE BY NAA

摘要: 用预浓集中子活化法测定了达拉布特蛇绿岩中超镁铁质岩中的稀土元素(REE),用仪器中子活化法测定了其中的过渡金属元素。依据测定结果分析了过渡金属及REE的地球化学特征。认为,二辉橄榄岩X12可能代表原始地幔的化学成分;二辉橄榄岩X10,X11和含矿的纯橄岩X17,方辉橄榄岩X18为上地幔经历了部分熔融后残留的地幔物质;不含矿的纯橄岩X8和异剥橄榄岩X7,X9为自镁铁质熔融体在上地幔内以堆晶作用形成的超镁铁质岩类。

Abstract: Abundances of REE in ultramafic rocks from Dalabute ophiolite are determined by preconcentration neutron activation analysis,contents of transition metal elements(TME) in them are measured by instrument neutron activation analysis.According to geochemical characteristics of REE and TME,indicating that lherzolite X12 represents primary mantle in the studied area. Lherzolite X10,X11 and orebearing dunite X17,harzburgite X18 are refractory residue left after partial melting of the upper mantle.The nonorebearing dunite X8 and diallageperidotite X7,X9 could be derived from the deepseated ultramafic accumulate developed in a mafic liquid under a highpressure condition within the upper mantle.