Sonoma State University on Tuesday announced a $15 million deal with MasterCard Worldwide to sponsor an outdoor pavilion at the Green Music Center.

The pavilion will enable the music center to host large-scale performances — including jazz, reggae and other international genres, as well as ballet — that draw a sizeable audience, said Erik Greeny, interim vice president for university development.

MasterCard Worldwide's name will be incorporated in the pavilion's name in perpetuity, but the naming details have not been worked out, he said.

The sponsorship deal also must be approved by the California State University Board of Trustees at its meeting next Tuesday.

SSU said it is the largest sponsorship ever secured by the university, and it was arranged by the Joan and Sandy Weill, the philanthropists who gave SSU its largest cash gift. The Weills will get credit for the MasterCard sponsorship, Greeny said.

The couple gave SSU $12 million last year to complete the Green Music Center, including its signature 1,400-seat Tanglewood-style concert hall named after the Weills.

Sanford "Sandy" Weill is a former chief executive of Citigroup, which he built into the world's largest bank before the financial meltdown of 2008, and is a nationally recognized philanthropist. The Weills bought a 362-acre estate in the hills west of Sonoma for nearly $31million in 2010.

Greeny said the MasterCard sponsorship is "just another example of their extraordinary leadership."

The Weills, both lovers of classical music, have been talking to other patrons of the arts, both private and corporate, about the music center, Greeny said.

"They have a vision shared with Don Green and (SSU President) Ruben Armi?na that we will have a world-class facility," he said.

Green, a telecom valley pioneer, kicked off the music center project with a $10 million donation. Total cost of the center was pegged last year at $120 million.

Green Music Center's inaugural 2012-13 season opens the weekend of Sept. 29-30 with performances by concert pianist Lang Lang, the Santa Rosa Symphony and Alison Krauss & Union Station, a bluegrass group.

The Weills' gift financed completion of the main concert hall. The pavilion, a permanent, all-weather tent structure with seating and landscaping, will be built on the east side of the concert hall. A third venue — the Schroeder recital hall — remains an empty shell and SSU needs $5 million to complete it, Greeny said.

The pavilion will accommodate "more contemporary music," including performances that involve amplification, he said. It also will be large enough for ballet and symphony pops performances.

Other major contributors to the music center include Jean Schulz, wife of Peanuts cartoonist Charles Schulz, $5 million; Evert Person and his wife, Norma, former owners of The Press Democrat, $3 million; telecommunications executive John Webley and his wife, Jennifer, $2.1 million; Herb Dwight, onetime CEO of the former Optical Coating Laboratory and his wife, Jane; $1.2 million; and the Trione Foundation, founded by financier and businessman Henry Trione, $1.1 million.

Conference at Sonoma State University

Three panel discussions will be open to the public for free. All will be held at Person Theater:

Hidden Sonoma: Laboring Voices and Hidden Voices. 11:30 a.m. Thursday

Nepantlan Warriors, Laboring Bodies and Communal Practices. 11:30 a.m. Friday

Water, Plantas y Medicina: Lessons from the Anti-Dakota Access Pipeline Movement, 11:30 a.m. Saturday

For more information, click here.