The Greencards perform Saturday at MerleFest

With their Sugar Hill Records debut, it’s official.

Fascination describes the essence of this band. It was, first of all, their fascination with American roots music – bluegrass especially – that drew singer/bassist Carol Young and multiple string-instrument master Kym Warner from Australia, and violinist/violist Eamon McLoughlin from the U.K., to Austin, Tex., where they began performing together, and later to their current home base in Nashville, Tenn.

That urge to challenge themselves, to test the limits of any established genre, guided them on their first three albums. It kept them focused as they accumulated awards and acclamations, from the Americana Music Award in 2006 for “Emerging Artist of the Year” through tours with Bob Dylan and Willie Nelson to last year’s “Best Country Instrumental Performance” Grammy nomination for “Mucky the Duck,” a track from Viridian in 2008.

All of which leads to Fascination, the band’s most daring accomplishment to date. Meticulously crafted arrangements serve as springboards for exhilarating improvisations. Acoustic textures shimmer in the light of Jay Joyce’s innovative production. On a dozen tracks, a dozen vistas open: an urgent urban scene on “The Avenue,” a dreamy shadowland on “Three Four Time,” a fiddle-sweetened reverie on “Outskirts of Blue,” a hallucination, as much silence as substance, equal parts jazz, blues, and Pulp Fiction on “Into the Blue,” a blaze of virtuosity unleashed on “Little Siam,” a mesh of pizzicato pulses on the title track that sounds something like a reggae jam inside a grandfather clock.

Complex and rich as Fascination is, the motivation behind it couldn’t be simpler. “We set out to make this music different from anything we did on our first three albums,” Young said. “So we wrote accordingly. And we took much more time than we’d ever taken before. Normally, we start writing a couple of weeks before recording ...”

“...and this time, we took eight or nine months,” says Warner.

Writing on the road, The Greencards rode an accelerating current of creativity. They produced more prolifically than ever and, more important, evolved their sound beyond anything they might have anticipated even just a few years ago. Almost apprehensively, they tried out some of this material at bluegrass festivals, beginning with the title track.

“There’s nothing bluegrass about that song,” Warner said, laughing. “We played it live just two days after we wrote it, and I was really surprised at how well it was received.”

“This older gentleman came up to our merchandise desk and asked specifically for Fascination,” Young added. “He actually said to me, ‘Hey, I like what you guys are doing – even the weird stuff.’”

The Greencards think of Fascination as a puzzle whose pieces form one varied but unified image, whose music speaks as one voice, directly to the heart.

More than that, Fascination represents the band’s achievement of its primary goal, which is to draw from the roots while also advancing the possibilities of the music that inspires them, with each side of this equation nourishing the other. Just as important, it challenges The Greencards to maintain this process onstage and in its future visits to the studio, by raising the levels of what they expect from themselves.

“We went into the studio on Fascination from Day One that this wasn’t The Greencards two years ago – this is us moving forward,” Warner said. “The issue with us now is where that’s going to take us over the next year.”

“We have so many new songs to play and a new approach to present to audiences,” Young says. “That gives us something to work for. But that also makes it so much more interesting.”

The Greencards will take MerleFest’s Creekside Stage on Saturday, April 25, at 5 p.m. and Sunday 1 p.m. on the Hillside Stage.