摘要
At the Luoji area of Shangri-La county in Yunnan Province, a suit of mafic rocks composed of Luoji Fm. basalts and basic dikes are outcropped, of which the parental magma derived from alkaline and sub-alkaline tholeiite series. Geochemical characteristics suggest that the mafic rocks formed in a complex environment of tectonic movement, associated with a mixture of magma from different source areas as well as crust-mantle hybridization of some degree. In this area, alkaline basalts and basic dikes belong to OIB basalts, which are the products of deep mantle garnet peridotite and spinel peridot partial melting, formed in continent interior or a transition from a continental marginal rift to an orogenic belt at a basin margin. Sub-alkaline basalts belong to E-MORB basalts and have a trend of transforming to OIB basalts. They are the products of relatively shallow spinel peridot melting, and reflect the Mid-ocean ridge turning into continent, which are the composition of ophiolite and residual products of the Gaze-Litang suture belt.