As unlikely collaborations go, Icon Give Thank is hard to beat. Armed with some rough musical templates, Cameron Stallones (a.k.a. Sun Araw) and M Geddes Gengras, two noted authors of heavy-lidded psych-improv from the US West Coast, travel to Jamaica to record with the legendary, recently rejuvenated roots reggae vocal group The Congos, mainly famous for 1977’s Lee “Scratch” Perry-produced masterpiece Heart of the Congos. As portrayed in Icon Eye, the documentary film that accompanies the album, the American visitors ended up living, sleeping, eating and smoking (this ranks amongst the most deeply stoned recordings yet produced) in the Congos’ H.Q. in St. Catherine (about a 45 minute journey from Kingston) for ten days. The closeness has really paid off. Icon Give Thank isn’t about one artist faxing in hastily cobbled vocals to tag on to music coined in isolation by the other. Neither is this in the style of Jamie xx’s superb Gil Scott-Heron remix album We’re New Here, where the younger artist remoulded existing music by the veteran. Neither party is expecting the other to bend to their favoured methods: this is a genuine collaboration, a truly organic symbiosis of sounds and styles, the participants blending seamlessly into one another whilst maintaining their unique musical identities.

Both parties benefit. Often self-indulgently fragmentary and needlessly noodle-y, the hazy soundbeds cooked up by Stallones and Gengras find a compelling anchor and, crucially, warmth and heart from the presence of the Congos. The vocal group, meanwhile, gain by having their traditional offerings – heaven-bound harmonies and simple melodies delivered in praise of Jah – welded to the unmistakably contemporary experimentation of their American visitors. It doesn’t matter how many reggae cuts about giving thanks and praise you’ve encountered: you’ve never heard these topics covered quite like they’re tackled here. Although not strictly speaking roots or dub reggae, Icon Give Thank recharges the timeworn templates of roots reggae, an offshoot that ruled Jamaican music during reggae’s ’70s reign but has since seen its spiritual, righteous concerns relegated to the margins as coarser concerns have taken hold of the island’s music biz.

OK, OK, but what does it all sound like? Despite the project’s boundary-stretching, oddness-embracing ethos and Stallones’ and Gengras’ impeccable psych-noise credentials, this is essentially an album of tunes: simple, timeless, hymn-like and hugely infectious tunes escalated to otherworldly radiance by the blissful contributions of the Congos. The fact that these songs are then twisted to startlingly unpredictable shapes is what makes Icon Give Thank such an unexpected, exciting treat.

It’s best not to expect Icon Give Thank to yield its secrets easily, however. On first encounters, the album can be a patience-exhaustingly unhurried deal, with seemingly disembodied noises and sleepy melodies glittering in the distant horizon like an alluring yet forever unattainable mirage, The Congos trying to locate their cues amidst the dense musical brew. Stick with it, though, and repeated exposure brings these initially half-formed songs, which appear to drift in slowly through a thick heat mist, into sharp, hugely hypnotic focus.

These are sounds that appear to emerge straight from the soil. Built on a disorientating rich foundation fashioned out of a few simple ingredients (Icon Give Thank definitely takes a few pointers from Black Ark-era Lee “Scratch” Perry’s less-can-be-more ethos), ‘Jungle’ is presented so that the malformed “riddim” – Gengras’ keyboard noise eruptions fraying everything around the edges – appears to drift in from one side of an echo-laden valley. The Congos deliver their declamations from the other side, with the listener stood at the bottom of the densely-foliaged valley in the middle, open-mouthed in awe as the dubwise bass line rumbles underground. Powered by a restlessly bubbling rhythm track of heavily treated guitars and the pounding of a bass-enhanced hand drum, ‘Happy Song’ is at least as mesmerising, The Congos appearing to float on a rickety raft atop the choppy waves that propel the tune. ‘Sunshine’’s creepy, treacly underwater crawl sounds positively sunburnt, with Stallones channelling his inner echo chamber-frequenting “Scratch” to the max.

Elsewhere, ‘Invocation’ embarks on its unhurried journey as a standard-issue vocals-and-percussion rasta chant, only to be catapulted to outer space once the first buzz of bass kicks in at around 2:15. The results are respectful yet rulebook-shredding; challenging convention without ever undermining the spiritual heft of the Congos’ performances. By the tranquil closer ‘Thanks and Praise’ we’ve entered an area – extra-terrestrial dub-folk gospel – that really doesn’t sound much like anything ever done by either party individually: in other words, collaboration at its finest.