I try not to be an angry tin foil hat guy, but this has powerful people's hands all over it it. Sorry, but it does. T bonds being bought and sold and shuffled and monetized all over the place. The age of moral hazard is in full swing.
Edit (3:37) Well, I knew it had something to do with the FOMC minutes and here is Bloomberg with the details... FOMC Saw No Need of New Monetary Easing. I would have thought that the QE3 obsessives would have long since given up, but evidently they were still in the markets to enough of a degree to give a nice post-FOMC knee jerk.
As for the gold stock sector, for better or worse, there is a cut and dry parameter in play there. On the plus side for most markets, these knee jerks can often last a day or so before a world full of casino patrons with the attention span of gnats, goes back about its business.