LOS ANGELES - With its muscular $70 million opening weekend despite scant appeal for guys, "Twilight" has redefined expectations for the chick flick.

While offering some high-flying vampire battles, its main action centers on the developing romance between two teens played by relative unknowns Kristen Stewart and Robert Pattinson. Women and girls made up more than 75 percent of the film's opening-weekend audience, according to Fandango.com, which sells tickets and conducts surveys about recent releases.

With the movie's stellar opening weekend - it trounced the celebrated $55.7 million opening of "Sex and the City" - studios ought to take notice of women's continued ticket-buying power, said Paul Dergarabedian of box-office tracking firm Media By Numbers.

"The word 'chick flick' is going to have to be replaced by big box-office girl-power flick," he said. "The box-office clout of the female audience is just astounding, and it's been an underserved audience for way too long. ... They have no trouble finding money for the things they're passionate about."