MOSCOW, Jan 10 (Reuters) - The rouble soared past 75 against the dollar on Monday, before paring some gains as Moscow and Washington held crunch talks in Geneva amid fears over a Russian military buildup near Ukraine, and with investors watching mass unrest in neighbouring Kazakhstan. With trading activity subdued during Russia"s New Year"s holidays, the rouble was buffeted last week by events in Kazakhstan, where thousands have been detained and public buildings torched during anti-government protests, the worst unrest in three decades of post-Soviet independence. read more The rouble had earlier firmed past 75 for the first time since Jan. 4, reaching a high of 74.8525, later giving up some gains to trade 0.8% stronger against the dollar at 75.13 by 1322 GMT. The Russian currency had also gained 1.1% against the euro to 85.06 , a six-day high. The United States and Russia began tough negotiations in Geneva on Monday, before talks involving other parties move to Brussels and Vienna later in the week. [nL1N2TQ0FH] Washington hopes it can avert the danger of a new Russian invasion of Ukraine without conceding to the Kremlin"s expansive security demands, though prospects for a breakthrough are dim. read more "In our baseline case, we expect geopolitical risks to ease in the short term and see the potential for the conflict in Kazakhstan to de-escalate, which may support the rouble," BCS Global Markets said in a note. The rouble should stay within the 73-75 range against the dollar if oil prices remain at current levels, it added. The start of the year is typically positive for the rouble due to favourable current account seasonality, said Dmitry Polevoy, head of investment at Locko-Invest. Brent crude oil , a global benchmark for Russia"s main export, was down 0.4% at $81.41 a barrel. Russian stock indexes were mixed. The dollar-denominated RTS index (.IRTS) was up 2% at 1,576.2 points while the rouble-based MOEX (.IMOEX) was 0.3% higher at 3,759.8 points. ($1 = 75.0550 roubles)