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

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.