George Mason University will build a 9,200-seat, $10 million sports arena to showcase its basketball program, possibly by the winter of 1985, Donald Mash, the university's vice president for student affairs, said yesterday.

The arena, authorized by the Virginia General Assembly as part of the George Mason revenue bond package, also will be used for indoor soccer and for other sports events, Mash said.

"There isn't a facility like it in Northern Virginia, so we can see a lot of interest in it," said Mash. "For anybody else in the area that would want to use this facility, there would be an opportunity to do so."

Part of a revenue bond package that also included an additional $10 million for dormitories for 500 students, the sports arena won approval in the waning hours of the General Assembly.

It will occupy approximately 6 1/2 acres somewhere on the George Mason campus near Fairfax City, Mash said, but the exact site has not yet been chosen.

Currently a school of 14,000 students, Mason is projected to increase to 20,500 by 1990 and is emphasizing basketball as one of its primary means of winning greater public recognition and exposure. This year's team was 13-14, but Mason deliberately sought an ambitious schedule playing such teams as the University of Virginia, James Madison, Old Dominion, Maryland and South Carolina.

Basketball Coach Joe Harrington said the new arena would have to help the program, particularly in recruiting top players.

"It's really important that we have a good place to play," said Harrington. "That's one of the big things on a young player's mind. 'Where am I going to play? Where am I going to practice?' This is a big step toward building a big-time program."

When completed, the arena would be one of the biggest indoor sports arenas in Virginia. Only The Scope in Norfolk and arenas at Virginia Tech, William and Mary and the University of Richmond can seat more people.

Mash said work will begin immediately on the design of the building and that a dome facility similar to the Carrier Dome in Syracuse is under consideration.

Mason currently plays basketball in a gymnasium on campus that seats 2,800. A recreation field house is under construction that should be ready by summer. "That will be for recreation and play, this (arena) will be our spectator facility," Mash said.

He said that because of the popularity of youth soccer in Northern Virginia, the George Mason soccer team will play indoor soccer in the arena.

Under current projections, the arena is scheduled to be finished by the fall of 1985, but Mash said it could be ready before the end of the 1984-85 basketball season.