In the spring of 1978 the Virginia Opera Association in Norfolk put itself on the national music map with its American premiere of Thea Musgrave's opera, "Mary, Queen of Scots." Last night at Wolf Trap the 4-year-old company gave an excerpt from that production just long enough to whet the appetite for more.

The scene presented was the dramatic confrontation of the second act between Mary, begging for her brother's loyalty, and James, demanding power as the price for his protection. The scene builds to Mary's recognition of James' motives and her angry denunciations of him as a traitor. Left alone she ponders her helplessness and then reasserts her determination to maintain her kingdom.

It is powerful drama, matched by music of strength and clarity. Musgrave knows how to propel events forward with forceful flowing lines and insistent rhythms. The scene revealed a possible weakness when it comes to her capacity to convey certain emotional states. The setting of Mary's plaintive line, "Alone - where can I turn?" failed to catch musically the poignance of that cry.

Repeating his performance in both the Edinburgh premiere and the Norfolk production was Jake Gardner, a baritone of rich vocal and dramatic resources. Recreating her role as Mary from the Virginia production was soprano Ashley Putnam, whose strong, pure voice and impressive acting talents are catapulting her into the front rank of young opera singers. Peter Mark, artistic director of the Virginia Opera Association and, incidentally, husband of composer Musgrave, moved the orchestra along with sure, dramatic instincts and enormous vitality.

In the second half of the program Putnam and Gardner turned to "La Traviata" with equally impressive results, both dramatically and musically. With exquisite shading on "Gior! Gior!" Putnam launched into a "Sempre libera" that brought the house down with its effortless agility.