We're in a new era of jumpy charts, which now reflect each ripple on the changing waves of popular taste. This week's surprise is Genesis, those venerable art-rockers, who-even though key members like Phil Collins and Peter Gabriel have long since gone their separate ways-stage a reunited debut this week all the way up at No. 4. Up-to-date hit maker Richard Marx, by contrast, bowed last week at only No. 40, and this week still didn't make the top 10. Michael Bolton, meanwhile, bounds back from No. 13 to No. 8, no doubt propelled by his version of ''When a Man Loves a Woman,'' the No. 1 single last week. LAST WEEKS ON WEEK POP ALBUMS CHART

1 1 GARTH BROOKS 10 Ropin' the Wind, Capitol Nashville 2 2 HAMMER 3 Too Legit to Quit, Capitol 3 3 ICE CUBE 3 Death Certificate, Priority 4 - GENESIS - We Can't Dance, Atlantic 5 4 NIRVANA 8 Nevermind, Geffen 6 5 GUNS N' ROSES 9 Use Your Illusion II, Geffen 7 6 METALLICA 14 Metallica, Elektra 8 13 MICHAEL BOLTON 30 Time, Love & Tenderness, Columbia 9 12 GARTH BROOKS 63 No Fences, Capitol Nashville 10 8 BOYZ II MEN 27 Cooleyhighharmony, Motown

2 WKS. AGO WORLD MUSIC ALBUMS

1 2 MICKEY HART 7 Planet Drum, Rykodisc 2 1 SALIF KEITA 15 Amen, Mango 3 3 GIPSY KINGS 19 Este Mundo, Elektra 4 4 BURNING SPEAR 13 Jah Kingdom, Mango 5 5 BEAUSOLEIL 17 Cajun Conja, Rhino 6 6 MARISA MONTE 17 Mais, World Pacific 7 13 ASTER AWEKE 3 Kabu, Columbia 8 7 ZIGGY MARLEY & THE MELODY MAKERS 21 Jahmekya, Virgin 9 10 LUCKY DUBE 9 Captured Live, Shanachie 10 9 PATRICIA KAAS 7 Scene de Vie, Columbia