Interior Department officials announced yesterday the discovery of "potentially significant" titanium-rich mineral deposits off the Virginia and Georgia coasts, a discovery that they said could lead to the first ocean floor mining along the East Coast.

The announcement sparked concern by environmentalists, who warned that mining of the sea floor deposits could disrupt marine life, disturbing fish, plants and sediment.

Assistant Interior Secretary Robert Broadbent stressed at a news conference aboard the research vessel J.W. Powell in Washington that more information is needed before it can be determined if it would be profitable to mine the titanium.

"We can't make commercial judgments on the basis of the few samples collected so far," he said, "but we definitely need to, and will, take a second look."

President Reagan set the stage for yesterday's announcement two years ago, when he claimed minerals within 200 miles of the U.S. shores, declaring an Exclusive Economic Zone, Interior officials said. The Reagan administration declared then that the United States should develop sea bed resources to lessen its dependency on imports of energy and strategic minerals.

Titanium is crucial to the aerospace industry, because it is light, strong, and resistant to heat, shock and corrosion. The United States is a leading consumer of titanium, much of which it imports from Australia.

The titanium deposits were found in a mineral called ilmenite, which is used to produce titanium and titanium dioxide. The latter is used as pigment in paints, plastics and other coatings, and to coat and protect welds.

The titanium discovered near Virginia was found in an area between 10 miles to 50 miles off the coast, and as far down as 20 feet, according to Edward Escowitz, the chief scientist on the research boat, which returned to its home port of Washington yesterday.

Escowitz said that the concentrations of titanium were greater than the concentrations generally found in the commercial mines on land. The initial onboard analysis of the sand and gravel found 3 to 10 percent heavy mineral, including ilmenite and zircon. By comparison, 3 to 5 percent heavy minerals are generally considered sufficient for commercial mining on land.

Escowitz said that there are added costs associated with mineral mining in the ocean, and that there are also additional environmental problems.

Carl Gawell of the National Wildlife Federation said later that, in general, environmentalists are concerned about deep sea mining, "because of the disruption to the ocean floor and marine life . . . . It raises lots of concerns."

"I would question whether they [the federal government] will apply strong environmental criteria to the leasing process," said Geoffrey Webb, Washington director of the Friends of the Earth, another environmental group. "The experience so far with the Reagan administration hasn't been encouraging."

Broadbent said Interior is developing regulations for a plan to lease offshore sites to companies that want to mine minerals. The regulations for leasing and operating the property are expected to resemble the offshore oil and gas regulations. A spokesman for Interior's Minerals Management Service said it could be several years before a leasing program is in place.

Escowitz said that a couple of companies, including the chemical giant DuPont, had indicated an interest in offshore mining of titanium, depending on the quality of the ore.

A DuPont spokesman said yesterday the company was not familiar with the test off the Virginia and Georgia coasts, which occurred during the past four weeks, but said the firm was always interested in titanium discoveries. He said DuPont is the nation's leading refiner of titanium dioxide.

Although titanium has not been mined offshore in the United States, it has been mined off the coasts of Malaysia and Sri Lanka, "so there is a backlog of technology to draw on," said Escowitz.