The Senate voted yesterday to authorize the construction of a novel and expansive memorial to Franklin D. Roosevelt in West Potomac Park, a stone's splash across the Tidal Basin from the classic marble rotunda that honors Thomas Jefferson.

The Senate action came on a unanimous voice vote, sending the measure to the House for final congressional disposition. Since, unlike the Republican-controlled Senate, the House is controlled by FDR's Democratic Party, approval there seems certain.

A memorial to Roosevelt, who was born 100 years ago last month and died during an unprecedented fourth term in 1945, has been under consideration since the mid-1950s. The plan authorized yesterday provides for a 27-acre site on a triangle of land that encloses the southwest side of the Tidal Basin across from the Jefferson Memorial.

Although the approved design for the memorial carries a cost estimate of about $24 million, the bill approved yesterday authorizes spending "such funds as may be necessary" to do the job.

Charles H. Atherton, secretary of the U.S. Fine Arts Commission, said the approved design calls for a series of water gardens, fountains and pools, together with bronze bas reliefs mounted on rich red granite depicting episodes in Roosevelt's life. The Japanese cherry trees that line the Tidal Basin shore would not be disturbed.