Abstract:

 This paper reports the investigation on the petrology of spinel harzburgite and olivine pyroxenite in the Darbut ophiolitic mélange, as well as the wormlike intergrowth texture composed of Crspinel and orthopyroxene widespreading in harzburgite (Western Junggar, Xinjiang). Our study shows that the observed intergrowth texture is not a graphic texture or a symplectite as assumed by previous research, instead, it is a product of the evolution of the Crrich magma formed after the melting of the primitive mantle. After highly fractionating, this Crrich magma formed massive chromite (i.e., Saertuohai chromite deposit), and the melt moved into the mantle rock, and formed the wormlike intergrowth texture consisting of Crspinel and orthopyroxene. Therefore, the intergrowth texture of Crspinel and pyroxene can be an important indicator for podiform chromite exploration. We also report the exsolution texture of Crspinel in orthopyroxene in the studied harzburgite, and suggest that it is the result of a metamorphic reaction induced by the drastic increase of oxygen fugacity during the rapid emplacement of Darbut ophiolite.

Key words:

Darbut; ophiolite; Crspinel; intergrowth texture; exsolution texture; Xinjiang