Days of Future Past with Kronos Quartet and Nicole Mitchell's Black Earth Ensemble

Music can thrill and entertain us. It can also suggest new ways to think about the past and the future. Two new albums by visionary California artists look backward and forward at the same time.

After more than four decades expanding the creative limits of classical music, San Francisco’s Kronos Quartet is more than capable of delivering surprises. On their latest album, “Folk Songs,” they’re exploring traditional American music with four guest artists who are all Nonesuch label mates: Natalie Merchant, Olivia Chaney, Sam Amidon and the Carolina Chocolate Drops’ Rhiannon Giddens.

Part of what makes “Folk Songs” such a departure for Kronos is what’s not here. We often expect instrumental pyrotechnics and exotic timbres from the ensemble. “Folk Songs” slows the action down, luxuriating in traditional American forms.

Working with imaginative arrangers like Gabe Witcher, Nico Muhly and Jacob Garchik (son of longtime San Francisco Chronicle columnist Leah Garchik), Kronos keeps the spotlight on the singers, who fully inhabit a series of soundscapes haunted by death, separation and judgment day.

In many ways the album’s touchstone is Amidon’s lugubrious take on “I See the Sign,” a harbinger of the apocalypse in which he sounds utterly resigned to the end. The song also served as the title track of his 2010 Bedroom Community album, an avant-chamber folk project featuring gorgeous arrangements by Muhly, who seems to distill that chart for Kronos. Muhly also contributes a starkly beautiful arrangement for Amidon on “Oh Where,” a traditional lament that opens the album.

Giddens seems to be everywhere these days, and her striking voice is heard to advantage on “Folk Songs.” Like with Amidon, Kronos features her on a song she previously recorded, with Gabe Witcher revamping his arrangement of “Factory Girl” (the title track of her 2015 Nonesuch EP). The contrast between the purity of her tone and the brutal story about an industrial disaster heightens the drama, which rises with Sunny Yang’s cello.

With so many bad tidings, rumors of war can’t be far behind, and Natalie Merchant continues her sojourn into Anglo-American roots music with “Johnny Has Gone for a Soldier,” a swirling, ache-filled arrangement by Garchik. After all the loss and devastation, Kronos closes the album with Giddens delivering Witcher’s brisk and beautiful arrangement of “Lullaby.” Thematically and musically, the quartet ushers string band-inspired music into the world of contemporary chamber music.

Nicole Mitchell’s Black Earth Ensemble

While Kronos reimagines the musical past on “Folk Songs,” flutist and composer Nicole Mitchell is exploring the future on "Mandorla Awakening II: Emerging Worlds." Recorded in concert at Chicago’s Museum of Contemporary Art, the album features her Black Earth Ensemble, a singular band built on a coruscating matrix of strings, percussion and winds (particularly the intertwined lines of Mitchell’s flute and the shakuhachi of Kojiro Umezaki, best known for his work in the Silk Road Ensemble).

Bristling with exceptional improvisers, the Black Earth Ensemble features the brilliant cellist Tomeka Reid (who doubles on banjo); violinist Renèe Baker; Tatsu Aoki on bass, shamisen and taiko; Alex Wing on electric guitar, oud and theremin; percussionist Jovia Armstrong and vocalist Avery R. Young.

Part song cycle, part suite — and very much an attempt to imagine a brave new world — "Mandorla" is set on an island in post-apocalyptic 2099. Inspired by writers like Octavia Butler, Mitchell paints another chapter in her ongoing Afro-futurist project, an attempt to imagine a realm in which gender and race aren’t vectors for oppression.

Like much of Mitchell’s music, there’s a lot going on. She can sound rootsy and avant-garde in the same phrase. One of the greatest flutists in jazz, she’s a strikingly expressive improviser, and her instrument is the album’s primary voice, though she also relies on vocalist Avery Young, who gives an incendiary, soul-steeped performance.

Mitchell grew up in Orange County and currently works as a professor of music in UC Irvine’s Claire Trevor School of the Arts’ integrated composition, improvisation and technology program. But she’s very much a product of the Chicago scene. Part of what makes her such a consistently enthralling artist is the way she’s forged a vividly idiosyncratic vision out of the disparate sonic strands running through Chicago's Association for the Advancement of Creative Musicians.

“Mandorla” is the latest dispatch from an artist pushing jazz forward from the inside and the outside. And while “Mandorla” and “Folk Songs” sound like worlds apart, it wouldn’t be a stretch for Kronos to commission Nicole Mitchell on some future project.