Two veteran box-office bruisers, Mark Wahlberg and Arnold Schwarzenegger, backed by their Oscar-winning cohorts Russell Crowe and Forest Whitaker, stormed North American movie theaters this weekend. Yet when the smoke cleared, the sheriff of the Martin Luther King holiday was a pale, thin actress virtually unknown two years ago. Jessica Chastain held the top two spots with the PG-rated ghost story Mama, which earned $33 million over the four-day weekend, and her holdover hit Zero Dark Thirty, which took in $18.7 million, according to preliminary studio estimates. Wahlberg’s urban-crime ... Read More