Sparks flew at a Monday night town hall organized by District 10 Councilman Marc Whyte as he and Mayor Gina Ortiz Jones — a guest at the event — traded verbal jabs over Project Marvel. Jones, who’s on a last-minute blitz to build support for a “strategic pause” on negotiations for the downtown sports-and-entertainment district, called on those attending the meeting at the Northwest San Antonio senior center to make sure Whyte knows what they think of the costly proposal. The $4 billion development would include a new Spurs arena, and the city would be on the hook for $489 million of the facility’s cost.