It was Gonzalez's fourth home run in the last five games, and he added two doubles. Gonzalez is third in the NL with 109 RBIs and tied St. Louis' Albert Pujols and Ryan Ludwick for fifth in home runs with 33.
For a team that has won just 58 games this year, Padres manager Bud Black is amazed at Gonzalez's season.
"He's had a very big year. I can't emphasize that enough," Black said. "The numbers speak for themselves. He's been incredible."
In 27 career games in Denver, Gonzalez is hitting .348 with seven homers, 10 doubles and 32 RBIs.
Gonzalez had help in dismantling the Rockies. Brian Giles had three hits and rookie Matt Antonelli hit his first career home run for the Padres, who had seven doubles in their 18-hit attack. Drew Macias also homered for the Padres, who had lost five of their last six games.
"We came out swinging right from the get go," Black said. "From Will Venable on down. Adrian swung the bat very well. Everybody contributed."
LeBlanc (1-1), making his third career start, allowed four runs and seven hits with six strikeouts in six innings.
"The first three innings went very well for LeBlanc," Black said. "He mixed his changeup and fastball and got outs when he had to after the Rockies adjusted to him."
Rockies starter Greg Reynolds (2-7), making his first start since being sent to Triple-A on July 5, gave up seven runs and nine hits in two-plus innings.
"This is more one of the more frustrating ones because I thought I had good stuff tonight," Reynolds said. "That's what eats at me."
It was the second straight poor outing for Reynolds. Against Florida on July 4 he allowed seven runs in 1 1/3 innings in a game the Rockies rallied to win, 18-17. He made six starts in Triple-A Colorado Springs before being recalled on Sept. 5.
"It's a large gap between Triple-A and major league baseball," Rockies manager Clint Hurdle said. "If you want to get here, you have to find ways to be consistent, pitch with an edge and get outs."
The Padres wasted no time in getting to Reynolds, scoring twice in the first before chasing him in the third. Luis Rodriguez and Giles singled to start the third, and Gonzalez followed with a homer to left-center.
"I'm facing younger pitchers and they are trying to establish themselves," Gonzalez said. "They make mistakes and I take advantage of that."
Headley gave the Padres a 9-0 lead with a two-out double in the fourth before the Rockies rallied in the bottom of the innings. With one out, Garrett Atkins singled, Iannetta walked and Brad Hawpe singled to load the bases. Tulowitzki followed with his seventh homer of the season and the second grand slam of his career to cut the lead to 9-4.
"You want to hit a grand slam on a day when you win," Tulowitzki said. "When you lose, it doesn't do too much."
Iannetta's 16th homer of the season in the eighth made it 10-5, but Drew Macias led off the ninth with his second homer to push the lead back to six.
Giles has reached base in 24 of his last 25 games. ... The Padres' seven hits in the third inning marked the second time they've done that against Colorado. They also had seven hits in the ninth inning of the teams' June 30 game. ... Tulowitzki's other grand slam was last Sept. 29 against Arizona.