The Flames announced the transaction in a press release.
Tanguay is returning to the team with which he started his NHL career and had the most success with. He was drafted in the first round (12th overall) in 1998 by Colorado and spent the first six seasons of his career with the Avalanche.
He had three more years left on a five-year, $17.5-million US deal that carries an annual cap hit of $3.5 million.
In 922 career games, the 33-year-old native of Ste-Justine, Que., has 249 goals and 762 points and spent the last three years in a Calgary uniform.
Sarich has 1,051 penalty minutes in 915 contests with the Tampa Bay Lightning, Buffalo Sabres and Flames.
In Jones, Calgary gets a top-six winger with some size, and that's something general manager Jay Feaster covets.
"This trade adds needed size up front and grit on the back end while also allowing us to get younger,” Feaster said in a release. “We like the fact that Jones plays a north-south game, drives hard to the net, kills penalties and is a right hand shot. O’Brien is a hard guy to play against, knows how to get under the skin of the opposition and stands up for his teammates. We are pleased to add both of these players to our organization."
Jones, 28, is coming off a down year in which he scored just three goals and six assists in 33 games for Colorado. But the Guelph, Ont., native is a two-time 20-goal scorer and has 70 goals and 56 assists in 272 career regular-season games.
The six-foot-two, 210-pound forward was originally selected in the ninth round (288th overall) by the Avalanche in 2003. He has three years left on a four-year, $16-million US deal with an annual cap hit of $4 million.
In O'Brien, the Flames get a rugged defenceman who's not afraid to throw his weight around.
In 483 career games, the six-foot-three, 230-pound rearguard has amassed 853 penalty minutes over his career. He's played seven NHL seasons with the Anaheim Ducks, Tampa Bay Lightning, Vancouver Canucks, Nashville Predators and Colorado Avalanche.