The Nuomin Ｒiver Quarternary volcanos are located in the northern of  the Greater Hinggan Range, at the northern part of the North-South Gravity Lineament. Mantle xenoliths from these volcanos include abundant Sp-peridotite (Ol_40～55Opx_20～35Cpx_0～10Grt_5～25) and subordinate Gt-peridotite (Ol_45～65Opx_30～40 Cpx_0～15Sp_0～10). Application of geothermobarometers to the mantle xenoliths suggests that the Gt-peridotites are equilibrated at a pressure of 2.14～2.33 GPa (corresponding to 70～75 km) and a temperature of 1 114～1 168 ℃. These data define a relatively high thermal gradient for the upper mantle beneath the Greater Hinggan Range, similar to those for many Cenozoic volcanic fields in eastern China.