Team to drill into un­der­sea vol­cano

Broth­ers ex­pe­di­tion will probe life forms able to sur­vive in ex­treme en­vi­ron­ment

The New Zealand Herald - - NEWS - Jamie Mor­ton

Dscience eep in the ocean, sev­eral hun­dred kilo­me­tres north­east of New Zealand, lies the world’s most hy­drother­mally ac­tive vol­cano.

The Broth­ers vol­cano is huge — it’s about three times the size of White Is­land and its sum­mit rises to within 1200m of sea level — and it sits in one of the most ac­tive re­gions of the planet, the Ker­madec Arc.

In a bold first, sci­en­tists will soon at­tempt to drill di­rectly into the beast’s belly, en­coun­ter­ing rocks as hot as 400C as they go.

The two-month-long in­ter­na­tional ex­pe­di­tion, set­ting out from Auck­land this week, will drill three bore­holes into Broth­ers. One is planned to reach a depth of about 800m in a cone grow­ing up in­side the sub­ma­rine vol­cano’s caldera.

The oth­ers will reach depths between 400m and 570m at the top and base of the caldera walls.

Led by the 23-na­tion In­ter­na­tional Ocean Dis­cov­ery Pro­gramme (IODP), the $21 mil­lion project aims to learn more about how met­als move through the Earth’s crust, while gain­ing new in­sights into lo­cal life forms some­how able to sur­vive in such ex­treme en­vi­ron­ments.

The ex­pe­di­tion’s co-chief sci­en­tist, Dr Cor­nel de Ronde, of GNS Sci­ence, has vis­ited Broth­ers 12 times be­fore, us­ing sur­face ships and re­motely op­er­ated ve­hi­cles, or ROVs.

All mag­mas con­tained small amounts of met­als, he ex­plained, but the magma and re­sul­tant vol­canic rock at Broth­ers was un­usu­ally rich in met­als such as cop­per, gold, sil­ver and molyb­de­num.

“We don’t re­ally know the full range of met­als and in what quan­ti­ties we will find at Broth­ers, or even how they are dis­trib­uted within the vol­cano,” he said. “But if the chim­neys sit­ting on the seafloor are any­thing to go by, we sus­pect we will see net­works of veins be­neath the seafloor that will be host to sig­nif­i­cant cop­per, zinc and gold min­er­al­i­sa­tion.

“This voy­age will in­crease our un­der­stand­ing of where these met­als come from and how they ac­cu­mu­late in sub­ma­rine vol­ca­noes, which may help in the ex­trac­tion of these eco­nom­i­cally im­por­tant and crit­i­cal met­als in sim­i­lar set­tings world­wide.”

Co-chief sci­en­tist Su­san Humphris, of US-based Woods Hole Oceano­graphic In­sti­tu­tion, said the ex­pe­di­tion would also help sci­en­tists bet­ter un­der­stand what reg­u­lates the chem­i­cal com­po­si­tion of sea­wa­ter.

“Chem­i­cal re­ac­tions between rocks and sea­wa­ter at depth in the vol­cano change the chem­istry of the fluid that is re­leased through hy­dro­ther­mal vents into the ocean.”

The team was also likely to find mi­crobes com­pletely new to sci­ence.

The hun­dreds of vents and chim­neys, some as tall as 20m, that dis­charge flu­ids rang­ing in tem­per­a­ture from 10C to 310C were fo­cal points for a wide range of ma­rine life, from mi­crobes to tube­worms.

As well as tol­er­at­ing tem­per­a­tures as high as 120C, some of the micro­organ­isms lived in flu­ids as cor­ro­sive as bat­tery acid — and ex­am­in­ing their tol­er­ance could help bi­ol­o­gists bet­ter un­der­stand how life be­gan on Earth.

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