* Oil sinks below $30 a barrel
* Aussie, kiwi, Canadian dollars all dive 1 pct or more
* U.S. dollar index edges down, though on track for weekly gain
* Eyes on U.S. retail sales, Fed's Dudley
By Patrick Graham
LONDON, Jan 15 (Reuters) - The Australian, New Zealand and Canadian dollars all sank on Friday on the back of another slide in Chinese stock markets and an almost 5 percent tumble in oil prices to less than $30 a barrel.
The dollar fell roughly half a percent against both the euro and yen EUR= JPY= and China's yuan was also back under pressure in offshore markets after Shanghai stock markets slid to their lowest point since December of 2014. ID:nL8N14Y1QC
Sterling, however, hit another 5-1/2 year low of $1.4331 GBP=D4 , helping to limit the dollar index's overall loss to just 0.2 percent against a basket of currencies. .DXY
"The oil market is just a mess and it all seems to be stemming from that," said Tobias Davis, a currency hedging manager with Western Union in London.
Richard Benson, co-head of portfolio management at currency fund Millennium Global, said the Canadian dollar - down by a third in value against its U.S. counterpart since 2012 - was suffering from bets on more easing of monetary policy next week.
"A lot of people are expecting the Bank of Canada to cut rates again next week," he said. "Its about 50-50 priced and the weakness of the currency might yet stop them. But dollar-Canada roofed it this morning."
By 0839 GMT, the Canadian dollar had fallen to C$1.4518, down 1 percent having hit a 13-year low of C$1.4545.
The Aussie dived 1.5 percent to an almost 7-year low of $0.6870 and the kiwi dollar 1.1 percent to $0.6395. The Norwegian crown weakened by almost 1 percent to 9.6205 crowns per euro.
All of that looked like the latest leg of a now deep-rooted concern in markets over the outlook for global growth and prices of commodities and other traditionally higher-risk asset markets.
Euro-dollar rates have largely ridden that out, but a handful of events over the next week should put the divergence of economic growth and monetary policy on either side of the Atlantic back at the front of investors' minds.
U.S. retail sales data on Friday are accompanied by an appearance by New York Federal Reserve President William Dudley. That all prefaces a European Central Bank meeting next week eyed for more signs on further policy easing this year.
"Generally all of this still comes down to the dollar and the diverging policies we've seen," said Brenda Kelly, chief market analyst at London Capital Group.
"This uncertainty dates back to the dollar's gains against the yuan in August. Those abated in December enough to let the Fed raise rates. But there is a chance that the strong dollar and the fall in commodities prices may mean the Fed will row back on those commitments." (Editing by Mark Heinrich)