Australia shares tumble as commodities decline weighs on resources

* Oil, iron ore, copper, gold down

* Chevron Caltex sale drags index

* Little upbeat economic data (Adds analysis, quotes, stocks on the move)

SYDNEY/WELLINGTON, March 30 (Reuters) - Australian shares fell sharply on Monday as resources stocks followed oil and metals prices lower, while investors failed to take inspiration from late Wall St gains on Friday.

United States energy giant Chevron Corp's $3.7 billion sale of its half stake in fuel firm Caltex Australia (Stuttgart: CLZ.SG - news) , Australia's biggest block trade ever, also pushed the benchmark lower in line with the stock's discounted sale price.

Caltex fell 10 percent to A$34.22 after Chevron (Swiss: CVX.SW - news) swiftly unloaded its long-held stake over the weekend at a floor price of A$34.20.

By 0128 GMT, the S&P/ASX 200 index was down 1.3 percent or 78.9 points to 5841.0, its lowest since March 19.

"The commodity market is definitely the major factor," said Quay Equities head of trading Tristan K'Nell.

"The market's going to be very similar to last week with a lack of econmomic data not giving much of a catalyst to drive markets forward."

Iron ore producer Fortescue Metals Group led its peers lower, dropping 4 percent after the key steel ingredient hit a record low last week. Larger rivals BHP Billiton (NYSE: BBL - news) and Rio Tinto (Xetra: 855018 - news) each fell nearly 2 percent.

Gold producer Newcrest Mining (Dusseldorf: NMA.DU - news) dipped 2 percent after the gold price fell.

Energy stocks fared worse as concerns that a potential Iran nuclear deal could put more oil into the market sent oil prices down 5 percent on Friday.

Woodside Petroleum (Xetra: WOPA.DE - news) declined 3 percent, Santos fell 6 percent and Oil Search lost 4 percent.

Banks outperformed the index amid hopes of a rate cut next week but still lost ground, with Commonwealth Bank of Australia (Other OTC: CBAUF - news) , National Australia Bank and Australia and New (KOSDAQ: 160550.KQ - news) Zealand Banking Group all down 1 percent.

New Zealand's benchmark NZX50 index slipped 22.1 points or 0.4 percent to 5,832.09, weighed by selling in health care- and consumer-related sectors.

Online auction site Trade Me (NZSE: TME.NZ - news) fell 2.1 percent after a media report said New Zealand's Inland Revenue services was cracking down on collecting taxes on goods sold online, which may curb sellers on the country's most visited website.

Synlait Milk tumbled 8.6 percent to its lowest since August 2013 after the milk processor announced a first-half loss, following weak results from dairy co-operative Fonterra last week.

Power generator Meridian Energy fell 1.5 percent while outdoor clothes retailer Kathmandu eased the same amount is it continues to struggle following last week's weak first-half results. (Reporting by Byron Kaye and Naomi Tajitsu; Editing by Kim Coghill)