The one indelible moment in “Björk” — a worshipful retrospective at the Museum of Modern Art, which has met with something other than critical approval — happens in “Black Lake,” a sound and video installation commissioned for the show. Björk is depicted alone, in a stark Icelandic landscape, furiously pounding a fist against her chest. She seems riven with despair, possibly trying to jolt her heart back into its rhythm, as unseen strings sustain a restive chord for an eternal half-minute or so.

At Carnegie Hall on Saturday afternoon — in her first of seven New York City concerts over several weeks, and the kickoff to a world tour — Björk imbued her performance of “Black Lake” with a subtler semaphore. Reaching that point in the song, she clasped her hands at her clavicle, as if grasping for composure. The chord, played by members of the new-music chamber ensemble Alarm Will Sound, became a ghostly ellipsis, hanging heavy and impassive in the air.

Heartbreak has been the overwhelming subject for Björk in recent months, as she readied and released her emotionally raw new album, “Vulnicura” (One Little Indian).

Coming after the end of her longtime union with the artist Matthew Barney, the album is her report from the epicenter of a recent devastation, issued in a spirit of elegy as well as rebuke.