DUBAI/BUENOS AIRES (Reuters) -Argentine authorities have grounded an Iran-linked Venezuelan Boeing 747 cargo plane, a local opposition lawmaker and Iranian state media said on Sunday, in an unfolding drama that is throwing a spotlight on political undercurrents in Latin America. The Emtrasur cargo plane, sold to Venezuela by Iran’s Mahan Air a year ago according to the Iranian airline, arrived in Buenos Aires on June 8, flight tracking data show. It was then seized by authorities, the lawmaker and Iranian media said. Argentina’s government has not publicly confirmed the seizure, but an Interio…