Artists, curators and gallery owners exchanged shocked phone calls today as word spread that Carl Andre, an internationally known Minimalist sculptor, was being held in a Riker's Island detention cell charged with second-degree murder in the death of his wife.

Detectives from Manhattan's 6th Precinct arrested Andre, 49, Sunday evening. In Criminal Court Monday, the Manhattan district attorney's office charged that Andre had intentionally pushed 35-year-old sculptor Ana Mendieta from the 34th-floor bedroom window of their Greenwich Village apartment. Bail was set at $250,000 and the case is expected to go before the grand jury within a week.

Andre's reputation has been established for more than two decades. "He's one of the most important sculptors who emerged in American art during the 1960s," said Patterson Sims, associate curator of the permanent collection at the Whitney Museum, which owns one of his series of floor pieces made of abutting copper plates. His sculptures are "stark and spare," Sims said.

Andre's uncompromising artistic vision has sparked some controversy. In 1976, the Tate Gallery in London acquired an untitled work consisting of 120 bricks for $1,000, to be installed on the floor according to the artist's instructions, and a furor resulted from the purchase. And in 1977, after the State of Connecticut paid $87,000 for "Stone Field Sculpture," a series of 36 uncut boulders set like so many standing stones in a Hartford public park, the mayor charged the artist had brought "international ridicule" to the city.

Mendieta was a Cuban-born artist whose work was attracting increasing notice after a Guggenheim Fellowship and a year at the American Academy in Rome.

"Things were starting to really happen for her; she was getting established as an artist," said Al Nodal, director of the Otis Art Institute in Los Angeles and a former director of the Washington Project for the Arts. Mendieta was one of 11 artists participating in Otis' program to install public art in Los Angeles' MacArthur Park.

In the aftermath of Mendieta's death and Andre's arrest, people who knew them struggled to understand what might have happened in their Mercer Street apartment Sunday. Assistant District Attorney Martha Bashford told the court that police had found scratches on Andre's face and evidence of a struggle in the apartment, and that a witness had heard a woman's scream early Sunday morning before Mendieta's body was found on a second-story roof.

Andre told police that the couple argued, that his wife went into their bedroom, and that he followed shortly thereafter but could not find her. The district attorney's office said in court that Mendieta had dinner plans that evening and had no reason to commit suicide, and that her husband pushed her to her death.

"It's painful for people who respect his art," said Ivan Karp of the O.K. Harris Gallery in SoHo. "We think of this turbulence, in a way, as affecting the future of American art."

Mendieta and Andre had been living together for several years, said friends, who added they were surprised when the couple married in January. Both were working in Europe at the time, and they had only recently returned from their apartment in Rome, according to Lowry Sims, associate curator of 20th-century art at the Metropolitan Museum, who had expected to meet Mendieta for lunch Monday. She was due in Los Angeles next week to continue work on her MacArthur Park piece.

"She was really full of life, a vital person," recalled friend and fellow sculptor Ron Fischer, who visited Mendieta this summer in Rome. "I don't think she'd even think of suicide." "That's not the woman I know."

Mendieta and her family left their native Cuba after Castro came to power, and she had a reputation in art circles for trying to promote interest in Cuba and its artists. She had visited her homeland several times, brought groups of visiting American art world people and had received several commissions from the Cuban government, apparently the only American artist to be so honored, Nodal said.

"She felt she could cross the boundaries," said Nodal.

Mendieta -- described by friends as short, wiry, dark, energetic and outgoing -- had felt her career slipping slightly after an initial groundswell of attention in the late 1970s. But she won a Guggenheim Fellowship in 1980 and had several group shows over the past several years. (In 1981 the Washington Project for the Arts commissioned a Mendieta street work, a mound installed at a cemetery on Wisconsin Avenue, Nodal said.) In 1983 she was one of two sculptors selected from 300 applicants for a year's fellowship at the American Academy in Rome.

She stayed on for an additional year, working on pieces fashioned from tree stumps and experimenting with fixing her earth sculptures so that they could be brought inside and exhibited in galleries.

"She was very active in Rome, getting out to make friends, building her career -- active and ambitious, in the best sense of the word," remembered American Academy President Sophie Consagra.

The demands of their dual careers kept Mendieta and Andre traveling, not always to the same places at the same time. They appear to have had separate groups of friends and associates. "This is a quite unexpected event," Patterson Sims said yesterday. "It's not as if one could say, 'Oh, yes, we always knew . . .' "

Both Andre and Mendieta are described as people with strong convictions, particularly about their work. Andre had changed galleries several times, which is not unusual. (He is currently represented by the Paula Cooper gallery on Wooster Street; Cooper was unavailable for comment yesterday.) He had arguments with curators he felt paid insufficient attention to the presentation of his sculpture, Patterson Sims said. He said Andre was "not very accessible, a little antagonistic, both towards certain curators and certain museums. He had very definite ideas about how objects were to be treated and shown . . . a very commanding presence."

"A man of intense idealism," added Karp. "Had very strong political convictions. Fiercely committed to his work, unrelenting in his dedication."

Such traits are unexceptional among artists, both added. "Sculptors are a very turbulent breed, a pretty fierce group," Karp pointed out. "Painters can be more sedate."

Mendieta, too, was known for her passion and a sense of mission about her art. "She was magical as a person . . . had incredible energy, a real feminist though not in a dogmatic way. She cared about her power as a woman," said Nodal.

Her uncompleted work for Nodal's MacArthur Park project, a circle of carved and burned totems entitled "La Jungla," probably will never be installed, Nodal said. But he plans to place a memorial tablet in the grove of trees where the sculpture would have stood.