UPDATE 1 — Striking unions at Antofagasta's Centinela copper mine reach preliminary deal, ending strike
(Adds context, detail throughout) SANTIAGO, Oct 16 (Reuters) — Workers from two striking unions at Antofagasta's Centinela copper mine in Chile reached a preliminary agreement on a new collective contract, ending a strike that has lasted more than a week at the mine, the unions said late on Friday in a statement sent t