As Mr Turnbull summoned business, union, and community leader to Canberra on Thursday for a mini-summit aimed at revitalising the reform conversation around company tax, as well as GST, retirement incomes, and education, Australia's heavily resource-based economy was given a timely reminder of its vulnerability to world markets, the declining role of the mining sector, which led the falls, and the urgent need to create new wealth across a broader base.

In a day of trading widely described as a "bloodbath", the benchmark index slipped to 4925.6, to be 3.8 percentage points lower than a month ago, taking it to a fresh two-year low.

That is down about 18 per cent from its recent highs in April. The Australian dollar continued to hold up amid the carnage finishing just below 70¢ US.

It was the worst day on the market since August 24, when the ASX200 closed 4.1 per cent lower, and the lowest point it has hit since July 2013.

Nonetheless, some analysts felt the sell-off - driven largely by a 30 per cent fall in UK-listed mining giant Glencore - was a little overdone with CMC chief markets strategist Michael McCarthy calling it a "classic sharemarket panic".

Mr Turnbull has called eight of the lead participants in last month's National Reform Summit to discuss ideas raised with a view to identifying areas of common ground. Among these are a consensus on a lower company tax rate, changes to high-end superannuation tax concessions, and the replacement of so-called inefficient taxes such as stamp duties, with more efficient and nationally consistent land taxes.

There is also the prospect of a further discussion around the GST, although unions, many crossbench MPs, and the opposition, remain opposed to that in principle due to the disproportionate impact on low income earners.

It came as the government continued to weather the political aftershocks of its September 14 leadership showdown, with defeated former prime minister Tony Abbott using his first radio interview to defend his record, and claim that no economic policies nor even the phrasing around them had changed.

However Treasurer Scott Morrison has confirmed that previously rejected proposals, such as curbs on superannuation tax concessions for the well-off, could be considered after all because all suggestions are back on the table in a post-Abbott atmosphere he characterised as "an opening up".

"There has been, I think, an opening up of what is being prepared to be considered," Mr Morrison said.

"We want to look at the system, and anything, any idea, that is going to encourage Australians to work more and work effectively and work more productively, that is going to save more effectively for their future ... we're not into the rule-in-rule-out game on the features, we know what the benefits need to be and if there are measures that are going achieve those benefits, great, let's look at them."

With the government treading a fine line between protecting its economic core on the one hand and justifying the leadership change on the other, Mr Morrison described Mr Turnbull's Thursday meeting as "a good opportunity" to bring considered collective views together.

"We should always be listening, I mean that's what good governments do, they're always listening," he told Sky News.

"They've got a large number of people together ... this is a good opportunity for them to bring their considered collective views directly and discuss it with the senior ministers in the government.

"One of the most important things I think together we can accomplish is this, whether it's particularly the tax system, where they've had a lot of discussion about that, how do we take the Australian people with us about the sort of changes that we need to make to the tax system that actually will boost economic growth going forward?"

He said the problem for the budget was not one of revenue but of spending, the answer to which was stronger growth.

"I want the economy to earn more. Now that's obviously taken some hits with movements in commodity prices and things of that nature, that will impact your earnings," he predicted.

One of the participants at Mr Turnbull's meeting, Australian Industry Group chief executive Innes Willox, described it as "a chance to kickstart discussions around developing a serious reform agenda to turn Australia into a leading edge 21st century economy".

"If there is not acceptance from all participants that the current economic model needs to be retooled so we can refocus our relatively slow and low growth economy, it will be a wasted opportunity," he said.

"Old thinking won't cut it anymore. To globally compete, our high-cost economy needs to put innovation at its fore to encourage start-ups and investment in new technologies and provide incentives for world-class research and development while making adjustments to increase efficiencies and maintaining our record of fairness."

In one of the worst days of selling on the ASX, investors responded to weakening demand from China and the prospect of an end to the cheap-money era provided by the US Federal Reserve.

According to the Bloomberg index of commodity futures, values have fallen 50 per cent since a 2011 high, revealing the days of the full-blown resources boom are over.