Abstract

The Núi Nưa peridotites, parts of ophiolitic complex of the Sông Mã suture zone, represent collision site between the Indochina and South China blocks. The peridotites are mainly composed of dunite, harzburgite and some intruded gabbro-diabases. Study of rock textures, mineral and geochemical composition indicated that they are typical those of mantle rocks, which were experienced partial melting in the mantle source. Mineral and geochemical composition of the harzburgites are used to calculate partial melting degrees of mantle. The results show that the mantle sources experienced partial melting degrees of around 20% to over 40% to form Núi Nưa peridotites. In comparison with data from different modem tectonic settings, the Núi Nưa peridotites were formed in a fore-arc tectonic setting.