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Dunedin’s ‘Pompeii’ to be mined to make pig food

A storm is brewing west of Dunedin where a majority Malaysian-owned company is planning on open-pit mining a geologically important site to make animal food.

The site, Middlemarch’s Foulden Maar, was formed 23 million years ago when a volcano erupted and formed a deep crater lake. The lake has since filled with the sediment from the microscopic diatomite plant and dried out, leaving behind a “cornucopia” of fossils.

Plaman Resources, which owns the land and mining rights to the maar, plans to dig out all of the the 23-million-year-old fossil-containing diatomite and turn it into food for intensively-farmed pigs, chicken and turkeys around the world.

Digging painstakingly through the layers of the diatomite has been a little like unearthing Pompeii. What’s destined to be pig food has already given scientists a glimpse into past life.

It’s the only maar of its kind in the southern hemisphere. A similarly important one in Germany is a world heritage site. Excavation is permitted, but only for scientific purposes.

“They think we are too poor and too ignorant to put up a successful fight.”

The diatomite - which has done such a good job of preserving the fossils - is used by the palm oil industry and in animal foods. Poor quality diatomite can be used in concrete.

Plaman Resources has registered the name of their proposed product: Black Pearl.

What’s standing in Plaman’s way is Overseas Investment Office approval to purchase a neighbouring farm. The additional land would improve the financial viability of the operation, improving access and ensuring the entire deposit can be excavated.

A 112-page confidential report written by Goldman Sachs, which has lent Plaman almost $30 million, was leaked to the Otago Daily Times. The report says former Labour MP Clayton Cosgrove has been engaged as a lobbyist to “secure approval” for the mine.

"Clayton has outstanding relationships with the ruling Labour Government and is doing everything possible to ensure a decision is made by the relevant ministers as soon as possible."

It also describes the Dunedin City Council as pro-mining and said the council had given letters of support for the project, highlighting the 100 jobs the mine could create.

The report is skeptical of community action blocking the mining.

"Any appeal to the Environment Court is likely to come from a small number of local residents, who are not well-resourced and will not have comprehensive technical reports to the same extent at Plaman Global would have."

Locals, who are meeting Saturday to discuss the impact the mine, its dust and constant truck traffic will have on their quiet community, paraphrase this as:

“They think we are too poor and too ignorant to put up a successful fight.”

Scientist Daphne Lee commissioned an ecologist and illustrator to recreate the flora and fauna at the site based on leaves, insects and fish which been found to date. Illustration: Dr Paula Peeters

A historical treasure chest

The maar has been part of University of Otago’s Daphne Lee’s career for years. She’s written 40 papers on it and given around 80 conference presentations since 2005.

She explained its uniqueness lies in the layers of diatomite which formed each year in the bottom of the lake. Over 120,000 years the shallow lake was home to a microscopic plant, diatomite, which bears silica. As the plant died off each year it formed a thin layer. Prising apart the layers are like opening the pages on a book of fossils for scientists.

“There’s no life at the bottom part of it [the lake], it’s anoxic. That means no bacteria decaying things. Picture a leaf blowing into the lake and drifting through the water to the bottom. There’s no decay process happening. The leaf will lie on one of these beds and the next year will be covered up by the next layer without decomposition. There’s no burrowing or swimming creatures there. It’s almost pickled.”

Layer-by-layer the lake pickled 120,000 years of fossils at a key time in the planet’s history - the beginning of the Miocene era. Dinosaurs had long-since vanished, but there were plenty of creatures and plants, and the climate was in flux with Antarctica cooling down.

Lee said so far only the centre of the lake has been surveyed. This has uncovered fish, spider, insect, leaf and flower fossils. Many of the species are now extinct.

The oldest galaxias (whitebait) fish in the world was found at the site.

"That fish is lying there as it sank to the bottom of the lake. Every little bone is intact."

She’s confident surveying an area closer to the shore will unearth birds, possibly even moa. 

“Think of a football field and a teaspoon. We’ve probably looked at one teaspoon full.”

A 23 million-year-old leaf found at Foulden Maar. Photo: Supplied

Lee is not alone in her belief in the importance of the maar.

A discussion is currently occurring among New Zealand's geological community and it's expected an official comment will be made in the coming days. Dr Bruce Hayward, a leader in identification and assessment of New Zealand geological heritage, shared his personal views with Newsroom.

“The diatomite in Foulden Maar is an irreplaceable treasure box from which only a small proportion of its jewels have been found so far. It is far too valuable a part of New Zealand's geoheritage to be quarried away and sent overseas for making fertiliser or other low-value products.”

He worries mining it for short-term financial gain is short-sighted.

“In future decades many new techniques and technologies will be developed that allow much greater interrogation of the rock sequence with potential for greater and more detailed understanding of the history held in the rocks and fossils.”

He doesn’t believe the mining operation - no matter how careful - will be able to preserve enough for scientists to use.

Lee, who has worked in the site extensively, said the best way to do it would be to mine half of the maar only and leave the other side for ongoing scientific excavation. Unfortunately, it’s not a viable solution.

“Imagine the lake as shaped like an ice cream cone. You would have to cut it down the middle so half of the full thickness is preserved. The problem is you can’t have a mine with a wall 120 metres high.”

Whether a wall 120 metres high is possible seems like a moot point according to the leaked Goldman Sachs report, which indicates the mine will only be a viable option if it reaches the predicted full production forecast of 500,000 tonnes a year.

The mining permit is valid until 2033 and the company estimates the area contains 31 million tonnes of fossil-rich diatomite.

Plaman, palm oil and pig food

The maar has been mined before.

Local Middlemarch residents Andrea Bosshard and Shane Loader, who are against the proposal, have looked into the history and claims made by the company.

They think the term Black Pearl used by the company is marketing. White diatomite is the purest form, black diatomite is low quality. Loader said he had been in contact with a previous owner of the farm.

“He said it’s very low quality. All they could use it for was as an additive in cement.”

A subsequent buyer of the land Featherston Resources went into liquidation. The company had attempted to turn the diatomite into fertiliser. It estimated the reserves of diatomite to be five to six million tonnes and of too low a quality for many markets. 

In 2014 Plaman Global, known for purchasing distressed assets, bought the operation.

Plaman’s biggest shareholder is Iris Corporation, a Malaysian-based company which initially planned to use the diatomite as a fertiliser on palm oil plantations.

Since then, the plan has been revised to create an animal food additive from the diatomite.

The Goldman Sachs report includes talk of removing Iris Corporation as a shareholder to “remove any links” to the palm oil industry, saying this would be viewed positively by ministers.

Unrest in Middlemarch

Loader said the mine has divided the local community.

“There are people there saying it’s going to be a boom time, the best thing since sliced bread.”

Others may need to move out of their houses, according to Loader.

“Their house will be so close to the road, which will have to be widened to allow the number of heavy trucks. Their house will literally be metres away from the road. Those trucks will be coming past every six minutes.”

Bosshard and Loader plan to make a presentation at Saturday’s community meeting which may spur local action.

“I think that we will probably come out of that meeting with an agreement to set up an incorporated society. That’s my hope for the meeting.”

The pair have talked of the opportunity to create a "geopark" in the area instead of a mine.

Scientist Daphne Lee would like to see an eventual outcome of at least half of the site preserved in perpetuity.

"From a scientific perspective we don't yet know the importance of what it contains. If it's completely destroyed now, in the future people are going to say it would be like destroying Pompeii, 'Why did you do that?'"

Clayton Cosgrove and Plaman Resources have been approached for comment but did not respond by the time of publishing.

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