Effects of the strike-slip fault on the thermal structure and mantle flow of the mid-ocean ridge and the interpretation to RRF triple junctions at the southern Pacific boundary

Triple junction provides a natural place for studying the interaction of plates. In this paper, we chose two ridge-ridge-fault （RRF） triple junctions with different relative plate velocities at the southern boundary of the Pacific Plate, namely, the Macquarie triple junction and the South Pacific triple junction. We studied the effects of relative plate velocity of the strike-slip fault on the mantle flow and temperature structure of the RRF triple junction by numerical simulation method. We can conclude the following results: ① The relative plate velocity of the strike-slip fault of RRF triple junctions at the southern boundary of the Pacific controls the mantle flow and temperature distribution near triple junctions. ② With increase of the relative plate velocity of the strike-slip fault, the slip velocity of the transform fault and the temperature increases, while the effect on the velocity distribution of mantle fluid concentrates within 100 km from the boundary of the ridge. ③ The relative movement of the three plates at the Macquarie triple junction and the South Pacific triple junction makes the shear stress concentrate in the shallow boundary of the transform fault, which results in the centralized distribution of earthquakes with focal depth in a range of 15−25 km. ④ The topography is mainly controlled by the change of the mantle temperature from the mantle flow caused by the relative motion of plates.