Look magazine yesterday served its 2-month-old management contract with Rolling Stone by dimissing editor Jann Wenner and "dissolving" its editorial staff, thus throwing the future of the beleaguered monthly into doubt.

"They unilaterally decided to stop publication," Wenner said yesterday evening, even as Look assistant publisher Didier Guerin insisted that "the magazine will continue to come out."

Look executive vice president Gerald de Roquemaurel called a staff meeting at noon yesterday to dismiss the magazine's employes following an earlier decision by Look's seven stockholders that Wenner's editorial concept "required larger investments of capital than was left advisable."

By 1 o'clock some two dozen new staffers were departing -- a couple of them with their typewriters and even some video equipment in tow. So management quickly changed the door locks, and by late afternoon a mere skeleton crew remained in the offices.

Look has been plagued with financial and personnel problems since it began publishing again in February under French management. The mast-head listings have changed more than the scratch sheets as Pimlico. In half a year, well over 50 staffers have been axed: editors and secretaries alike with equal swiftness.

Daniel Filipacchi, board chairman of Look and publisher of Paris Match, was traveling "somewhere on the continent" yesterday, and could not be reached for comment.

But his assistant, Guerin, explained the situation with Gallic insouciance:

"We're reorganizing the company," he said. "How it will be reorganized we don't know."

Although Guerin insisted that there will be a September issue of Look -- the August issue, produced by Wenner's new team, goes on sale July 20 -- he said he has no idea who will put it out.

"We are considering several new editors now," he said. Asked whether he thought many new editors would dare to step into such murky waters, Guerin replied:

"That is a terribly awful question."

Guerin praised Wenner's efforts and his long-term business plans, but said "the stockholders believed that this country is going into a recession that will affect publishing -- and didn't want to invest a large amount of capital that wouldn't have a fast return."

Through its nine issues, the new Look has consistently lost money and last month switched from a bimonthly to a monthly format. The first monthly issue -- July, with an Avedon portrait of Clint Eastwood on the over -- is an uninspired mixed bag that Wenner said he had to put out in one week.

"I had a great time at Look," Wenner said yesterday, "and I think we learned in a month how to do that kind of magazine. So we came away with knowledge and two $50,000 monthly fees Look paid Rolling Stone to manage it.

"We're gonna go ahead and look for another magazine," Wenner said. "I'm turned on and juiced up. In my heart I've always wanted to do a glossy for young people about people and life-styles. We'll do that magazine again, in March or September of '80. If we can buy the name Look we might use it.

"For now I'm just gonna put my energy into Rolling Stone. It was Filipacchi's money, he owned it and it was his decision to dump us. I think it was a terrible, stupid mistake.

"But I'll tell you one other thing. Next time I won't have financial partners who are French."

Once referred to by a Jesuit high-school teacher as "Playboy with maps," the eternal National Geographic this month sports a new cover, with its 90-year-old black and white trim of leaves removed from the top of the logo.

"Actually the cover's been quite fluid, if you want to call molasses fluid," says associate editor Bill Garrett who, with 25 years of seveice, might be considered a Geographic novice.

"The cover has really been evolving since 1957, when we started putting pictures there," Garrett says. "That border of leaves has been shrinking constantly ever since. There's no real thought process there. We all agreed it was long overdue. We're just trying to open the book up, make it more readable. There are some people who've said we've killed the golden goose, but reader response has been very good."

The July issue of America's third most popular magazine [circulation 10 million, behind TV Guide and Reader's Digest] is devoted to the National Park System, with a handy, concise road guide included. It also debuts a new typeface created for the Geographic's captions, "to set the information off better from the text," Garrett says.

Garrett, incidentally, was recently responsible for one of the more ambitious practical jokes in the magazine business. When the German magazine Geo began publishing here, its publisher chided that it would attempt to crack the American market by placing a yellow border around its issues.

Garrett responded by having a few special copies of the Geographic printed replacing its yellow borders with the green rim that Geo uses -- and mailed a copy off to Geo's publisher.

"They went crazy," Garrett says. "My Teutonic sense of humor really hit."

The most consistently well researched and extensively documented information on science-fiction and horror films is appearing in Cinefantastique, a quarterly available from PO Box 270, Oak Park, I. 60303 [ $10 annually, $18 for two years.]

The latest special double issue, on the making of "Forbidden Planet," includes an 84-page article on the production, sketches of set designs, the interior workings of Robby the Robot and scores of production stills that would delight even the most jaded film buff.

Cinefantastique's earlier issues on the making of "Star Wars" and "Close Encounters" have become the classic compendiums of state-of-the-arts special-effects work. Both are still available with a two-year subscription.

The phenonmenally growing interest in science-fiction and horror films has prompted the creation of two new magazines by the publishers of Star-log, the modern romance monthly for the extraterrestrial set. Since the introduction last year of Future Life, a science magazine with a technological bent, Starlog has created the memorabilia-drenched Fangoria that focuses on the horror genre and Cenemagic, which provides tips for would-be George Lukases who want to create special effects with the family Supre-8.

Starlog [$11.98 annually], Future Life [$13.98 annually], Fangoria [$9.98 annually] and Cinemagic [$5.99 annually] are all available from O'Quinn Studios, 475 Park Avenue South, New York, N.Y. 10016.

As gas lines grow, energy conscious souls are directed to the quarterly Home Energy Digest [$7.95 annually from 8009 34th Ave. South, Minneapolis, Minn. 55420] which contains some remarkably thorough reportage on garnering energy from wood, as well as to the Solar Energy Digest, a monthly compilation of abstracts on new products, processes and government programs [$30.50 annually from box 17776, San Diego, Calif. 92117].

The Girl Scout's American Girl, published since 1917 and the oldest teen-age magazine in the U.S., ceases publication with its July issue. With a circulation of 629,000, it was the 94th most popular magazine in the U.S.

In announcing the decision, Girl Scout Executive Director Frances Hesselbein said that a survey had found that a significant percentage of the magazine's readers had become non-Girl Scouts, and the organization "felt it more appropriate that resources of the Girl Scouts be used to provide program for its members." CAPTION: Pictures 1 and 2, Jann wenner, right, dismissed after his first issue, left, of Look; Pictures 3, 4, 5 and 6, National Geographic magazine from left, February 1959, June 1971 and July 1979; and the quarterly Fantastique.