Anne Burnett Windfohr Marion, a prominent Texas rancher, oil heiress and patron of the arts who helped found the Georgia O’Keeffe Museum in Santa Fe, N.M., died on Feb. 11 in Palm Springs, Calif. She was 81.

The cause was lung cancer, said Neils Agather, a family representative.

Mrs. Marion represented the fourth generation of a renowned Texas ranching family that once owned more than a third of a million acres; today the holdings amount to about 275,000 acres. Its 6666 Ranch, known as the Four Sixes, has long been one of the biggest in Texas and much celebrated for its Black Angus cattle, quarter horses and oil. In the 1960s and ’70s, its distinctive red and white barn provided the backdrop for Marlboro cigarette ads.

While the family fortune was founded on ranching and cattle, it was the discovery of oil, in 1921 and then in 1969, that produced the riches that made it possible for Mrs. Marion to become a major benefactor of the arts and culture in Fort Worth and beyond.

Former President George W. Bush, in a statement, called her “a true Texan, a great patron of the arts, a generous member of our community and a person of elegance and strength.”