MELBOURNE (Standard&Poor's) Jan. 29, 2015--Standard&Poor's Ratings Services said today that its ratings on Australian mining company Fortescue Metals Group Ltd. (BB+/Stable/--) are unaffected following its revised assumptions for benchmark iron ore prices. On Jan. 20, 2014, Standard&Poor's lowered its assumptions for benchmark iron ore prices (based on Platts' benchmark for 62% iron [Fe] content including costs and freight [CFR] to China) to US$65 per ton for the rest of 2015, and for 2016 (see article titled, "Standard&Poor's Makes Significant Downward Revisions To Its 2015-2017 Metals Price Assumptions," published Jan. 20 2015). We previously assumed benchmark iron ore prices of US$85 per ton. Although the lower iron ore prices would have a material