Shadow Morton, a songwriter and producer who for a brief, luminous period in the 1960s poured the discontents of adolescence into original hit songs, including “Leader of the Pack” and “Remember (Walking in the Sand),” died on Thursday in Laguna Beach, Calif. He was 71.

The cause was cancer, said Amy Krakow, a family friend.

By all accounts possessed of a brazen, naïve genius — he played no instrument, could not read music and wrote his songs in his head — Mr. Morton was almost single-handedly responsible for the wild success of the Shangri-Las, the Queens girl group he introduced and propelled to international stardom.

The group had its first hit in 1964 with “Remember,” recorded more or less on a dare in a session frantically pulled together by Mr. Morton, who had never written a song before.

The result, with lyrics and music conceived by Mr. Morton in what he later said was about 22 minutes, was released on the Red Bird label and reached No. 5 on the Billboard singles chart.