By Clara Denina and Iain Withers LONDON (Reuters) -The $53 billion planned merger between Anglo American and Teck Resources announced on Tuesday marks a breakthrough after years of failed mining sector consolidation attempts and could spur their rivals to action. The sector's second-biggest ever tie-up that would create the world's fifth-largest copper company appears to have broad support. Anglo shares rose 9%, while Teck stock was up 14% after the announcement. Rivals Glencore, BHP, and Rio Tinto, whi ...