Thirteen studio albums in, Norway's Enslaved are still pushing at the boundaries of the music that inspired them back in 1991 when guitarist Ivar Bjørnson and vocalist/bassist Grutle Kjellson (13 and 17 years old at the time) first formed the band.

With a lineup that has been constant for more than a decade, they have continually redefined the parameters and possibilities for black metal.

In Times is, in many ways, a continuum of the sonic approach they began exploring on 2009's Monumension.

Co-produced by the band and Iver Sandøy and mixed by Jens Bogren, In Times projects the rage, swirling darkness, and fury (which have been there all along) stitched inside progressive elements, sonic ambiences, and even psychedelic explorations while remaining black metal.

The songs are sprawling but the arrangements are tight.

The concept is an exploration of the human notion of time itself through consciousness, metaphysics, mythology, and pagan spirituality, and the lyrics are as sophisticated and poetic as the music.

Check the eight-plus-minute opener "Thurisaz Dreaming." It begins with blastbeats and screaming amid downstroked guitar riffs, single six-string flailing, and bass throb, but winds out over eight minutes toward the unknown with clean vocals, woven keyboards, alternate tempos, and even chants, before unwinding and climaxing in an orgy of anger.

"One Thousand Years of Rain" is like a suite, where black metal aggression meets knotty prog and tinges of post-psych -- there are even Gentle Giant-esque vocal interludes and field recordings woven into the mix, yet it never loses it ferocity.

The title track commences with a straightforward, repetitive, two-chord cadence in midtempo before keys, a guitar solo, and a melodic bassline assert themselves.

In the backdrop, clean, layered vocals wordlessly flirt with the margins, enhanced with reverb and space.

After one is thoroughly taken in by its hypnotic quality, the screaming black metal assault begins after about two-and-a-half minutes, but changes just as quickly to prog metal; it shifts every few minutes until it builds into a near operatic climax.

This is metal sprawl of the best kind, with aural surprise after aural surprise.

In Times is all the more remarkable (though Enslaved fans should be used to it by now), because despite their growth -- musically and production-wise -- they have never forgotten where they came from.

They have understood that black metal is a root music that quite naturally lends itself to explorations of other themes, rockist subgenres, sonics, and songwriting structures.

With In Times, Enslaved prove once again that they are among the few survivors of their generation that have never repeated themselves, nor have they morphed into something so unrecognizable that they're merely another metal band.

This is vital, bracing music.