Trends in Q3 M&A activity By Trevor Zeyl (Toronto) on October 31, 2012 Canadian M&A activity was down sharply in Q3, but the proposed $15.1 billion takeover of Nexen Inc. by China National Offshore Oil Company Limited drove the overall value of deals up 23% over Q2 and 16% over Q3 2011. PricewaterhouseCoopers…