Helen Frankenthaler’s abstract paintings allude to landscapes and moods; a showcase of the artist’s work from the ‘90s at Gagosian Gallery conveys the pleasures of colors and feelings observed in nature. Pioneer of an influential staining technique in mid-century American abstraction, Frankenthaler here adds an overt, textured brushstroke that emphasizes the surface of the canvas. Appearing to hover over aqua-toned pools of color and an underlying dark depth, the long orange mark sets in play a complicated and shifting illusion of depth. (On view through April 15th on 24th Street in Chelsea).