"The reason that the survey work is being undertaken as I understand it is because there are many other benefits that may flow from that data collection including geological information, so they can look at faults, for instance."
Green Party MP Catherine Delahunty was concerned that major mineral findings in precious conservation land would lead to pressure from the industry to mine it.
She said even if world heritage sites were omitted from mining plans, mineral companies could ruin the protected land by digging around the fringes.
The United Nations Educational, Scientific and Cultural Organisation (Unesco) identified Te Wahipounamu as one of 183 worldwide sites with "outstanding universal value".
It contained flora and fauna linked to ancient super continent Gondwana, as well as spectacular glaciers and endemic and rare species such as kea, takahe and kiwi.
Environmental groups wanted the Te Wahipounamu land to be re-categorised as Schedule 4 to ensure it would remain untouched.
Similar aeromagnetic flights took place in Northland last year, which resulted in the opening of a tendering process for exploration permits last month.
Ms Delahunty said the same arguments for the wide value of surveying were made in Northland, but mining interests were the only parties represented at results of the research.
The National-led Government backed down on plans to mine Schedule 4 land - the highest rated conservation land - in 2010 after a major groundswell of public opposition which climaxed with a march down Queen Street.
Since that U-turn, consent has been granted to a huge open-cast mine in the biodiversity-rich Denniston Plateau, also on the South Island's West Coast.
Australian mining company Bathurst has been granted permission to take coal from the 160 hectare site - which was not under Schedule 4 protection - and the company was awaiting permission to access it and dig under the plateau to reach the coal.
