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Sat 9 Apr, 2005 04:32 am
Science - SPACE.com/LiveScience.com
SPACE.com
Hole Drilled to Bottom of Earth's Crust, Breakthrough to Mantle Looms
Thu Apr 7,10:22 AM ET
Robert Roy Britt
LiveScience Senior Writer
LiveScience.com
Seeking the elusive 'Moho'
Scientist said this week they had drilled into the lower section of Earth's crust for the first time and were poised to break through to the mantle in coming years.
The Integrated Ocean Drilling Program (IODP) seeks the elusive "Moho," a boundary formally known as the Mohorovicic discontinuity. It marks the division between Earth's brittle outer crust and the hotter, softer mantle.
The depth of the Moho varies. This latest effort, which drilled 4,644 feet (1,416 meters) below the ocean seafloor, appears to have been 1,000 feet off to the side of where it needed to be to pierce the Moho, according to one reading of seismic data used to map the crust's varying thickness.
The new hole, which took nearly eight weeks to drill, is the third deepest ever made. The rock collection brought back to the surface is providing new information about the planet's composition.
"It will provide important clues on how ocean crust forms," said Rodey Batiza, program director for ocean drilling at the National Science Foundation (NSF).
Already the types of rocks recovered show that conventional interpretation of Earth's evolution are "oversimplifying many of the features of the ocean's crust," said expedition leader Jay Miller of Texas A&M University. "Each time we drill a hole, we learn that Earth's structure is more complex. Our understanding of how the Earth evolved is changing accordingly."
The latest drilling was done at the Atlantis Massif, located at the intersection of the Mid-Atlantic Ridge and the Atlantis fracture zone, two plates of the planet's broken crust. The seafloor is shallower at the center of this region and therefore easier to reach.
It's not clear yet whether drilling should continue at the new hole or if another one should be started in the effort the reach the mantle. Such work isn't likely to begin again in the next year, said Barbara John, a University of Wyoming geologist and one of the co-chief scientists on the expedition.
"We need to evaluate all the data we have from the cruise and re-analyze the seismic data, to determine whether it's better to deepen the current hole or drill elsewhere, or maybe even collect additional seismic data to better constrain where to drill," John told LiveScience. "Our major result is that we've recovered the lower crust for the first time and have confirmed that the Earth's crust at this locality is more complicated than we thought."
John said mantle material will be evident when and if it's brought up because it will have different texture and chemistry and will contain different proportions of minerals compared with rock in the crust.
Drillers use the vessel JOIDES Resolution. The 10-year, $1.5 billion program is funded by the NSF and Japan's Ministry of Education, Culture, Sports, Science, and Technology.
So this makes me wonder, couldn't they just dissect a volcano, or extinct volcano, in order to determine the same thing?
Also, what happens if they pierce the crust and the mantle begins oozing out, or worse, blows out followed by magma?
Or worse yet, the whole planet pops like a balloon which has been stuck with a pin?!!?
Logic tells us that the the volcanoes which already exist don't get their magma from this side of the crust but the interior. Since the magma doesn't care where it exits and since there is more territory under the ocean than above more of those exits are there than on terra firma. The hole being punctured is miniscule by comparison. You would be much more in danger from magna which would not be able to vent than otherwise.
Thats impossible! lava would come welling up in suck huge ammounts its hard to imagine! we could all die in a cloud of smog! okay.. maby not but anyway i dont belive it.
Welcome to a2k einherjinn. The fact of the matter is lava comes out of volcanoes all the time. We don't die from it if there is enough distance between us and it so the ash, lava and noxious fumes can dissipate. There is generally room. Warning systems and communication has gotten better so that cataclysms such as Pompeii are averted. If this venting did not occur as it has throughout history then the big bang theory would would almost surely be proven in dramatic fashion.
Since the hole is small, a rapid flow of lava is very unlikely. More likely the lava won't rise to the top of the hole and the drilling vessel is in little danger. The worst I can imagine is a new volcanic island will form in a century or two from the lava that lesks out. Neil
The Russians (Soviet) were trying to do this in the 80's from a site somewhere around Murmansk. Does anyone know how that turned out?
Who is the hoaxer in this?
The last I read the Russians were having difficulty keeping the drill bit in a vertical position it kept veering to a horizontal position.
I think they abandoned the hole, but directional control shouldn't have been a problem. They weren't rotating the drillstring in the conventional manner - the bit was driven by a turbine driven by the drilling fluid and direction was controllable. I believe this was a Russian invention, by the way. It is now the usual method of drilling slant holes in the US oilfields.
I would be interested in the drilling fluid (mud) used in these very deep boreholes. It has to have the sufficient density to keep an uncased bore from collapsing.
Thanks roger, I often wondered what happened, I have not seen a published account of that project in years.
Why! To what purpose are they drilling. Is it just because they can or what. Just thought I would ask.
I think in part just to see what is down there (curiosity). There are questions as to what the lithosphere is composed of at lower depths and just what exactly is the MOHO or Mohorovicic Discontinuity . Here is a web site that can explain it much better than I can.
http://www.le.ac.uk/geology/art/gl209/mainlct1.html
I thought as much. It always bugs me when I read about the billions of dollars spent on projects of this kind. Could not and should not those funds be put to a more practical and better use.
Actually there are a number of very practical purposes to this. I might note that the geology department is in the same building I'm in and I talk to those folks quite a bit. Sumatra is at the moment the main victim of our ignorance of what goes on down there.
The money isn't simply handed over the the geologists to burn or bury. Check get written to steel companies and trucking firms and local motels and restaurants.
Quote:The Russians (Soviet) were trying to do this in the 80's from a site somewhere around Murmansk. Does anyone know how that turned out?
We all know that their country fell apart because of this foolish attempt by the USSR to drill to the center of the world. It shattered into several pieces. We must stop this drilling now before the same thing happens to us. Its obvious drilling down that far is as bad as building a tower to the sky like they did in Babel. :wink:
Thank god they didn't attempt space travel, huh, parados? They could have destroyed the entire solar system.
Before you ask, I did recognize the irony.
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