The electoral coalition that catapulted Sharon Pratt Dixon to her upset victory in Tuesday's Democratic mayoral primary was nearly identical to that which launched Marion Barry's mayoral career: impressively strong support in largely white areas and respectable numbers in majority-black neighborhoods.

A precinct-by-precinct analysis of election returns shows that Dixon's showing among blacks in the five-way contest surpassed that of Barry in 1978, when he first captured the mayor's office in a landmark victory over two major opponents.

Like Barry, Dixon piled up substantial pluralities in the racially mixed core areas of Wards 1, 2 and 6 and in the affluent and predominantly white upper Northwest neighborhoods of Ward 3, while also picking up her home turf, Ward 4, a predominantly black and middle-class section of Northwest that rebuffed Barry in his first bid. Dixon won 59 percent of the vote in Ward 3, which Barry carried with 47 percent in 1978.

In the race for the Democratic nomination for D.C. delegate to Congress, Eleanor Holmes Norton decisively defeated four opponents by carrying six of Washington's eight wards, despite the last-minute disclosure that she had failed to file her city income tax returns for seven years.

Dixon, a lawyer and former utility company vice president, spent yesterday receiving congratulatory calls, meeting with reporters and making conciliatory gestures to her erstwhile opponents. Several key Democrats on Capitol Hill called yesterday to say they were prepared to work with her in dealing with the city's mounting financial problems should she defeat Republican Maurice T. Turner Jr. in the Nov. 6 general election.

The impressive depth and breadth of Dixon's support should serve her well in November, in part because Democrats outnumber Republicans 8 to 1 in the District. Should Dixon capture the mayor's office, the biracial quality of her political base also could help her in any effort to unite blacks and whites, while serving as a mandate for change in city government.

Dixon's victory showed that "the demand for newness and innovation in how the District government is run is pretty broad," said Robert L. Johnson, a onetime Barry supporter who ran D.C. Del. Walter E. Fauntroy's campaign for the mayoral nomination this year.

"Her trick now is to take this thing and run this revolution and turn it into the government," Johnson added.

Although the results in the mayoral primary showed Dixon's strength among blacks and whites alike, voting in the party's primary for D.C. delegate broke more sharply along racial lines.

D.C. Council member Betty Ann Kane (At Large) carried Wards 2 and 3 by large margins over Norton, whose support among whites in those areas apparently fell dramatically after the disclosure about her income taxes.

Nevertheless, Norton remained strong in Ward 4, where she built a better than 2 to 1 margin over Kane, and in Wards 7 and 8. Norton carried Ward 8 with 4,040 votes, while Kane ran fourth, with 861 votes.

A number of political observers and advisers to Dixon rival John Ray, the summer-long front-runner in polls who collapsed in the last-minute surge by Dixon, attributed his loss in part to an overly cautious campaign that gave voters few compelling reasons to vote for him over Dixon.

"Ray never delivered a reason to vote against her," said one close adviser to the at-large D.C. Council member, who asked not to be identified.

Added D.C. Council member Jim Nathanson (D-Ward 3), "Ray got complacent and began a holding action, and that was not enough."

Strategists for most of the five Democratic campaigns cited an editorial campaign by The Washington Post as perhaps the turning point for Dixon. They said it helped confer on Dixon a status as a legitimate alternative to four veteran politicians at precisely the moment when undecided voters began making their decisions about the race.

At the same time, observers credited Dixon for fashioning a clear and powerful message to tap voter discontent with Barry's 12 years of dominance in city politics.

"She got the I'm-mad-as-hell-and-I'm-not-going-to-take-it-anymore vote," said Mark L. Plotkin, a onetime Democratic council candidate and political commentator on radio station WAMU-FM.

"It was head and heart," Plotkin said. "She appealed to their intellect and to their emotions."

Citywide, Dixon received 42,194 votes or 35 percent of the record total for an off-year election, followed by John Ray with 26 percent, Charlene Drew Jarvis with 21 percent, David A. Clarke with 11 percent and Fauntroy with 7 percent, according to complete but unofficial returns.

Dixon's success was not limited to Wards 1, 2, 3, 4 and 6. She ran third behind Jarvis and Ray in Wards 7 and 8, predominantly black areas of Northeast and Southeast Washington, but second only to Ray in his home base of Ward 5, the upper Northeast area that includes some of the precincts with the highest turnout in the city; Dixon managed to carry five of the 17 precincts in Ward 5 and lost half a dozen others by narrow margins.

If Dixon's support was broad, it alsowas deep, the returns indicate. For instance, in Precinct 130, an affluent and largely white enclave on Capitol Hill, Dixon's four opponents averaged 35 votes each, while she won 221 votes.

In Precinct 66, which has more registered Democrats than any other precinct in Washington, Ray won with 831 votes, but Dixon finished a strong second, with 695 votes. Similarly, in Barry's home precinct, 110 in Ward 7, Dixon again finished second to Ray, but only by a whisker, 543 votes to 541 votes.

While Dixon was eroding Ray's lead in the polls with her pledge to "clean house" in District government, Ray displayed tremendous confidence, suggesting it was impossible to lose so late in the campaign.

However, when a voter survey by WJLA-TV (Channel 7) detected a late Dixon surge and a narrow Ray lead on Friday, four days before the election, the Ray campaign was faced with the task of slowing Dixon down with virtually no time left.

"It was clear we had a big, big problem when we saw that on Friday," said one Ray confidant.

With the advantage of morning-after hindsight, some Ray advisers said yesterday the seeds of his defeat may have been sown early in the campaign, when Ray decided on a positive, feel-good message that cast the longtime council member as a role model for youth and a quiet, judicious alternative to the Barry era.

Those themes, said one strategist, were the first ingredients of what was to have been a three-part strategy. Ray was to give those first messages a sharper edge by recounting his accomplishments, and then hone the theme even further by contrasting himself with an opponent or saying specifically what his policies and goals would be in the future.

Instead, "we never got to the end in our campaign," said one Ray aide.

In other developments, Dixon and Turner, a former D.C. police chief, squared off for the first time yesterday in a brief appearance on WRC-TV (Channel 4).

Turner criticized Dixon's proposal to fire 2,000 city employees, saying the government work force should be trimmed through attrition. Dixon cited the surge in drug-related crime and violence during Turner's eight years as chief, adding "I don't think that's a record to run on."

Staff writer Michael Abramowitz contributed to this report.