Christmas Island seamounts: is the mystery finally solved?

The CHRISP forms a diffuse volcanic belt with an E–W length of ~1,800 km and a N–S width of ~600 km and is divided into four sub-provinces: (1) Argo Basin (136 Myr), (2) Eastern Wharton Basin (94–115 Myr), (3) Vening-Meinesz (64–95 Myr; Christmas Island 37–44 and 4 Myr), and (4) the Cocos/Keeling (47–56 Myr) volcanic provinces.

Also shown is Outsider Seamount (53 Myr). Plate motion vector and rate from UNAVCO model.

From MSNBC

If you ever find yourself on a leisurely submarine ride through the northeastern Indian Ocean, be on the lookout for some amazing views: more than 50 large seamounts, or underwater mountains, dot the ocean floor, some rising as high as 3 miles (4,500 meters).

The Christmas Island Seamount Province, as the area is known, spans a 417,000-square-mile (1 million square kilometers) swath of seafloor.

Just how the massive underwater structures got there has been up for debate, but some new geochemical detective work may have solved the mystery.

The seamounts are made of recycled rocks from the ancient supercontinent of Gondwana, said geochemist Kaj Hoernle of the University of Kiel in Germany.
Their turbulent geological history explains the massive size and puzzling placement of these features.

Ubiquitous and mysterious

Tens of thousands of seamounts line the floors of the world's oceans, but exactly how most of these formed is unclear.

Some, like the Hawaiian–Emperor seamount chain that extends northwest from the Hawaiian Islands, formed over hotspots in the mantle, just as the islands themselves did.
Other seamount chains were created when tectonic plate boundaries and other fractures in the ocean crust allowed lava to escape and harden at the surface.

Lavas on Christmas Island, north-east Indian Ocean

But the Christmas Island Seamount Province doesn't fit either of these models, Hoernle said. The structures are too widespread and diffuse to have formed over a single hotspot; they’re also aligned perpendicularly along breaks in the ocean crust, which means they didn't form above a fracture.

"We knew they were volcanic," Hoernle told OurAmazingPlanet, "but beyond that, it was more or less a mystery."

Geochemistry to the rescue

To solve the puzzle, Hoernle and his colleagues set out to map and collect samples of the seamounts.

The evidence they brought back to the lab told an interesting story: The rocks' geochemical signatures didn't match those from mid-ocean ridges or hotspot volcanoes.

Instead, they matched the signatures of continental rocks — in particular, rocks from northwestern Australia.

Around 150 million years ago, greater India, Australia and Burma — all once part of this supercontinent — began to rift away from each other.
This created the spreading center (or mid-ocean ridge) that eventually formed the Indian Ocean. As this was happening, the bottom part of the continental crust delaminated, or "peeled off in a sheet," Hoernle said.
The peeled-off continental crust mixed with the upper mantle, heated up and eventually was pulled to the surface again at the Indian Ocean spreading center.
"When the spreading center passed over that area, it essentially sucked the continental bits and pieces up again," Hoernle said. "Because these pieces have more volatile content (such as water and carbon dioxide), they produced more melted material than the normal upper mantle, and formed seamounts instead of the normal ocean crust."

The first seamount in the Christmas Island Province formed around 136 million years ago.
The spreading center continued to create seamounts until about 47 million years ago, when it migrated away from the part of the mantle containing the recycled continental crust, Hoernle said.
The team's findings are detailed in the December issue of the journal Nature Geoscience

Links :

• GeoGarage blog : Surprising sunken islands discovered near Australia

Book review: ‘Oceans Odyssey’

From TheEpochTimes

I met Greg Stemm’s partner in Odyssey Marine Exploration in South Dakota.
Of all places, South Dakota is not a likely place for an ocean explorer to be.
If he had been there when the ocean covered the place, Don Mann would have to be a lot older than he is.
Actually Mann was on another odyssey, filming for television’s “Primal Quest Badlands” episode.
Greg and Don’s quest underwater has taken them around the planet.
Their accomplishments have brought amazing deep ocean discoveries that include the steamship Republic that sank off Georgia in 1866, with a fortune in gold aboard.
(see NYTimes)

Odyssey Marine’s endeavors are the stuff of front-page newspaper headlines all over the world.
Recently The New York Times carried a story about their work with the British government on the discovery and planned exploitation of the British steamship Mantola.
A German U-boat sank the Mantola in 1917, off the Irish coast.
It went to the bottom with 20 tons of silver bullion.
That’s $18 million today.

Undaunted by success Odyssey discovered another prize off the Irish coast laden with 240 tons of silver.
The cargo is estimated to be worth $200 million according to the report.
The Gairsoppa was sunk by a German torpedo in 1941.
Odyssey is working with the British government and will partner shares.
Oddly enough the British Indian Steam Navigation Company owned both ships, one sunk in World War I, the other in World War II by German submarines.
The Mantola sank in the deep ocean a mile down.

Controversy still rages between private enterprise and some jealous academics about who gets what on the ocean floor.
By and large this often means who gets the credit for major discoveries.
One fact is very clear: if shipwrecks are not found, studied, mapped, and their cargoes recovered in an archaeologically acceptable way, the knowledge they contain and their valuable artifacts will be lost forever.
In this pursuit, no government and no academic institution has ever had the funding, resources, or expertise to do the job of deep-water archaeology properly.

The prejudice among academics and government bureaucrats has always been that private enterprise can never be compatible with archaeological recovery of shipwrecks.
Sadly, corruption in government labs and storage facilities resulted in the loss of major treasures that were recovered by the late Mel Fisher and his team of divers as well as others working with the State of Florida.

Private sector involvement has made the only significant contributions to, not only knowledge, but to public museum collections of maritime history in recent years.
Certainly this is true in deep-sea technology to a very large extent.

Oceans Odyssey by Greg Stemm and Sean Kingsley is a two-volume presentation of astonishing marine research and exploration that will open the eyes of experts and enthusiasts, alike.
Two major books have been recently published by Odyssey Marine Exploration as reports of their work.
The two volumes will be part of continuing efforts by Greg Stemm, Sean Kingsley, and Odyssey’s curator Ellen Gerth to document and publish, with scientific papers and reports, the results of their work on the SS Republic, HMS Sussex, HMS Victory, and other vessels lost in the deep oceans.

Both books are major undertakings in full-color, large 9” x 11” format.
Ocean Odyssey I contains 288 pages, Ocean Odyssey II is 354 pages.
The books publish papers produced by archaeologists and scientists working on the projects.
Some are technical or scientific and all are well researched.
The editors make no attempt to dissuade opinion since one paper contains the pros and cons of treasure hunters being involved with shipwrecks at all, authored by an archaeologist.
The color photography obtained in situ of deep-water shipwrecks is not only amazing it is beguiling.
To be able to see clearly about .31 miles beneath the surface, and see what no one has seen before since the ship went down, is an incredible feat.

On the SS Republic site, located about 93 miles off Georgia’s coast, in about .31 miles of water, the scatter fields of cargo and artifacts are revealed in minute detail in the pictures.
Recovered from the depths were 51,404 gold coins from the paddle-wheeler that sank in a terrible storm on October 25, 1865, while en route from New York to New Orleans.
Volume I contains reports of the field work, and site history, the cargo, coin collection, bottles, and other artifacts recovered from the shipwreck.

The book also documents what has been called the Blue China shipwreck off Jacksonville, Fla. with its cargo of porcelains.
When the 80-gun HMS Sussex went down in 1694, it was a major loss to the Royal Navy.
Now the wreck has been brought to light again with its history coming back to life.
Volume I describes Odyssey’s work on the about 109-yards-deep HMS Victory lost in the western English Channel.
The shipwrecks have been explored using Remotely Operated Vehicles (ROVs) equipped with cameras and powerful lights.
Intricately engineered limpets with rubber suction cups have been used to recover artifacts from the deep wreck sites after methodically mapping and recording the finds.

Greg Stemm and Odyssey Marine found the first colonial deep-water Spanish shipwreck in 1989.
Their excitement at the discovery challenged them.
Stemm’s introduction proclaims that there are some 3 million shipwrecks worldwide.
Many of the shallow water wrecks have already been pillaged before any archaeology could be performed.
Deep ocean wrecks were raked over by fishing trawlers and many sites have been destroyed by natural events.
What Stemm and his team have proved is that archaeology can be successfully performed using remote vehicles.
Odyssey’s engineers are responsible for developing the technology, at great cost, to make this possible.

In Stemm’s words, “We found that even in deep water, shipwrecks were being destroyed at an alarming rate and that the politics of underwater cultural heritage were so complex that some government bureaucrats were happier to see shipwrecks being destroyed in situ than to consider a new private sector model for managing cultural heritage. In addition, a handful of archaeologists in positions of power were dead set against the private sector coming into ‘their’ territory, a perceived threat to their funding sources and monopoly on underwater archaeology.”
Stemm uses the example of their discovery in 2008, of Admiral Sir John Balchin’s HMS Victory in the English Channel.
The shipwreck is badly damaged by trawling activities and natural causes, according to the book, documented with deep-sea photographs.

Volume II describes the UNESCO 2001 Convention on shipwrecks and its potential controversial application unless the requirement to work with others is enhanced.
Many German U-boats from World War II have been located by Odyssey Marine’s deep ocean surveys.
They have documented the U-325, U-400, U-650, U-1021, and U-1208.
Volume II also carefully describes in minute detail a carpenter’s rule found on their site 35F.
The book includes a paper about brass guns from HMS Victory.
One paper describes La Marquise de Tourny, a Bordeaux Mid-18th Century Armed privateer’s Art and Archaeology.
The volume includes additional carefully drawn papers about the Jacksonville Blue China wreck.
It was found to be a Mid-19th Century American schooner.
Curator Ellen Gerth and her colleagues describe the Ceramic Assemblage as well as the Glass Assemblage and Clay Tobacco Pipes found on the Blue China wreck site, about .23 miles deep and 70 miles off Jacksonville.
Photomosaics of the wreck site give clear details of the in situ wreckage that was first discovered by fishermen trawling the area over the last 40 years.
Trawlers dredged up porcelain artifacts in their nets.

For the academic, researcher, historian, shipwreck buff, diver, and ocean enthusiast Odyssey Marine’s two-volume set is indispensable.
While the papers are scientific they are easy to read and fascinating.
The photographs are amazing in fidelity and content.
The information contained in the volumes would require years of research to find in scattered archives.
The discoveries themselves are news of the century.
As reference books, the two volumes are required for archaeologists and maritime historians.
Additional volumes are planned and will be published as new material comes to light and the research is completed.

Links :

• GeoGarage blog : British shipwreck with a fortune in silver on board discovered in Atlantic

Coastal and ocean mapping: a nautical cartographer's perspective

CCOM Seminar - CDR Richard Brennan - Coastal and Ocean Mapping: A Nautical Cartographer's Perspective - 12/9/2011 from CCOM JHC

The Tank Bangers - Our Blue..

www.thetankbangers.org

Innovative, inspirational and scary.
A must watch for divers and anyone who cares about the marine environment.

The reality of ‘Finding Nemo’s’ marine life

From WashingtonPost

A new study found that when it comes to surviving in the non-Pixar sea, being adorable isn’t enough.

The underwater world in the Disney film is teeming with cheery creatures.
But a study says that of the real-life species associated with those in the film, many face the threat of extinction.
The underwater world on display in Disney’s “Finding Nemo” is teeming with a dizzying array of cheery creatures, from sea turtles to seahorses and mackerel to sharks.
So a team of Canadian and U.S. scientists decided to assess the mythical ecosystem inhabited by the small clownfish and his friends to see how their real-world counterparts were faring.
It turns out that when it comes to surviving in a non-Pixar sea, being adorable isn’t enough.

Sixteen percent of the species associated with characters in “Finding Nemo” that have been evaluated face the threat of extinction, according to the study, which was conducted by the International Union for Conservation of Nature (IUCN) and Canada’s Simon Fraser University.
The analysis of 1,568 species is not just a whimsical look at American popular culture and its cartoon characters.


It reveals how humans treat some of the ocean’s most charismatic inhabitants.
“These are species that should be doing better because they are the ones we care about,” said Loren McClenachan, a post-doctoral fellow at Simon Fraser University.
She said that highly migratory species such as turtles, sharks and rays are particularly vulnerable to fisheries and other human pressures.
“They’ve got life histories that cause them to interact with people wherever they go,” McClenachan said.
The Oscar-winning 2003 Disney/Pixar movie, which details how the clownfish Marlin defies all odds to save his son from the aquarium trade, has a conservation message.
But the film actually inspired a booming aquarium trade in the bright orange fish with white stripes, significantly reducing native clownfish populations on coral reefs in Australia and elsewhere.

While the IUCN classifies clownfish as a “species of least concern,” meaning it does not face an imminent extinction risk, 18 percent of the evaluated species that are related to Nemo — those of the scientific family Pomacentridae — are at risk of extinction.
There have been few formal scientific assessments of coral reef fish populations that are sought by the aquarium trade, McClenachan said, so “it’s very hard to know the true extent of the aquarium, live reef and curio trade.”Disney officials could not be reached for comment.

Boris Worm, a marine biologist at Canada’s Dalhousie University who has reviewed the study, which is being published Tuesday in the journal Conservation Letters, said the clownfish boomlet underscores the complex relationship humans have with marine species.
“When people see a beautiful film about tigers, they don’t go out and shoot a tiger. They don’t go out and purchase a tiger,” Worm said in an interview.
“In the case of things in the ocean, they think, ‘I care about them, so I’d like to have them,’ or, ‘I care about them, that’s why I’d like to fish them.’

Direct exploitation is the key driver of many of the species’ decline.
Many sharks are being targeted to make the Asian delicacy shark fin soup; seahorses are coveted as curios.

Other species, such as sea turtles, are vulnerable because they can easily get entangled in commercial fishing gear and because their nesting areas have been trampled or hampered by development.

Neil Hammerschlag, a research assistant professor at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science who studies sharks, said many people are unaware that sharks are under such pressure.
“They are truly the celebrities of the ocean,” Hammerschlag wrote in an e-mail.
“Despite their legendary status, most people are unaware that sharks are literally being fished to extinction.”

A survey of the animals with speaking parts in “Finding Nemo” gives a decent sense of how these species are doing.
More than half of all hammerhead sharks (personified by “Anchor” in the movie) face a threat of extinction, according to the IUCN, along with all species of marine turtles (“Squirt” and “Crush”).
Those species, McClenachan said, “are more threatened than the most threatened vertebrates on land.”Nicholas K. Dulvy, who co-authored the study and serves as the Canadian Research Chair in Marine Biodiversity and Conservation, said the group of species he and his colleagues analyzed is not representative of the ocean as a whole.
It is “a biased sample, but it’s biased in interesting ways,” he said.
Because the movie focuses on coral reefs and areas in the Indo-Pacific, he said, it captures key regions of “the world’s biodiversity.”
In some cases, these populations are beginning to rebound.
Nesting populations of marine turtles in Costa Rica increased by more than fivefold between 1971 and 2003, for example, after authorities began protecting nesting females there.


And the Convention on Migratory Species’ 116 member parties will ban fishing for giant manta rays and impose measures to safeguard their habitat after the group voted to protect the species.
Dulvy, who also chairs the IUCN Shark Specialist Group, said the paper aims to highlight the “conservation bottleneck” many species face even after researchers have documented their steep population declines.

Fewer than 10 percent of the threatened shark and ray species surveyed by the study are protected under the Convention on International Trade of Endangered Species of Wild Fauna and Flora (CITES).
CITES Director-General John E. Scanlon said in a recent interview that his group is working to build political support to protect additional marine species, as well as to raise funds from member nations to support legal enforcement of wildlife trade bans.
While many focus on the prospect of how climate change may drive some species out of existence, he said, “All the time we’re planning, we’re losing biodiversity through illegal trade and unsustainable trade of species. Why don’t we deal with the here and now?”
For the four authors of the Nemo paper, focusing on the here and now meant watching the movie four or five times.
But Dulvy said he came away with a better impression of the film than when he first saw it eight years ago, especially after watching Bruce the Shark struggle with his pledge to stop eating fish.
“They tried to portray sharks in a way more positive way than is usually done. But they showed them to be fallible, which makes them closer to reality,” he said.
“I really enjoyed it.”

Links :

• ScientificAmerica : Finding Nemo isn’t easy: film’s stars threatened with extinction