(Recasts with other financial details, market forecasts)
VANCOUVER, Oct 25 (Reuters) - Barrick Gold Corp, the world's largest gold miner by production, reported slightly weaker-than-expected third-quarter earnings on Wednesday, reflecting lower production and gold prices as well as the impact of an export ban on its Tanzanian unit.
The Canadian miner, which also produces copper, lowered the top-end of its 2017 production forecast range and raised the bottom-end of its cost outlook.
Barrick said it now expects to produce between 5.3 million and 5.5 million ounces of gold this year at all-in sustaining costs of between $740 and $770 per ounce.
It said previously that it expected to produce 5.3 million ounces to 5.6 million ounces at all-in sustaining costs of $720 to 770 per ounce.
Barrick's adjusted earnings declined to $186 million, or 16 cents a share, in the quarter from $278 million, or 24 cents a share. Analysts, on average, were expecting adjusted earnings of 17 cents per share, according to Thomson Reuters I/B/E/S.
Earnings were hurt by a tax provision of $172 million related to a proposed framework for its Acacia Mining Plc unit's operations in Tanzania. Barrick last week reached a tentative deal with the East African country, which has halted most of Acacia's exports. (Reporting by Nicole Mordant in Vancouver; editing by Grant McCool and Diane Craft)