1 week 1 hour from now
Seafloors Surfing the Asthenosphere (or, What is Seafloor Spreading, Anyways?)
The seafloor is spreading! The seafloor is spreading! To find out what this means, read on.
Let’s say you were an invisible, gigantic surfer who instead of surfing on waves, likes to surf on currents that move slower than you fingernails grow, but that speed is fun for you because you live for hundreds of millions of years. Also, you do not like to surf on liquid but instead you prefer to surf on stuff that is the consistency of Silly Putty. As the current of Silly Putty moves your surfboard, it will periodically break open gaps in the surfboard, which the Silly Putty then rises into, hardens and becomes new surfboard, and you think this is totally gnarly. If by chance an invisible giant who meets these criteria is reading this blog, then the ocean floor is your perfect surfboard.
The ocean floor is part of the lithosphere, which sits upon the asthenosphere (to find out what the lithosphere and the asthenosphere are, read this blog). The asthenosphere is made up of molten rock that is not liquid, but is more like Silly Putty. Even though the molten rock in the asthenosphere is Silly Puttyesque, it can move.
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As you probably know, heat rises (which is why a cold air balloon is not going to go anywhere). The molten material down near the core becomes really hot and rises up to the lithosphere. The lithosphere then becomes weaker in the places where all that hot, molten rock is pushing up against it. The lithosphere is like a ceiling, though, that stops the current of asthenosphere from breaking through and causes it to flow along underneath the lithosphere. As the current flows under the lithosphere, it actually drags the lithosphere with it, like a giant surfboard riding a really slow wave. When the lithosphere is dragged, it does not stretch, so it ends up breaking open in the same weak spot where the asthenosphere current first rises up to meet it. Some of the asthenosphere then rises into the gap in the lithosphere as lava. When the lava comes in contact with ocean water it immediately cools into rock, adding to the ocean floor and causing it to spread out.
So if the seafloors are spreading all over the world (and they are) does that mean that at some point the earth is going to be entirely covered by seafloor? The answer is no. To find out why, read my next blog.
Sincerely,
The Blogfish
Comments
Molten Material
Would molten material come out if you dug into the mantle and/or core and if it did, would anything happen to the ocean?
-Sophie
What if...?
IWhat would happen if you did reach the mantle and/or the core? What types of samples would you find?
-Sophie
This blog post could give you
This blog post could give you some ideas of what might be found deep in the earth: http://joidesresolution.org/node/1749
Clarify
Can the tools that you have reach the mantle or core?
-sophie
The tools we have on the ship
The tools we have on the ship right now would probably melt as we approached the mantle. It is a possibility to reach the mantle, though. Scientists call it the "Mohole Project" and we will be writing some blog posts about it very soon that can answer your question in more detail.
The world years from now
So in that case, if the seafloor is spreading all the time then millions of years from now would continents all spread apart into mini continents?
Continents do occasionally
Continents do occasionally break into mini-continents. This might be beginning to happen right now at the east Africa at the Great Rift Valley. The reason continents do not continue to break up in smaller and smaller pieces is plate tectonics will also push small continental plates back together to form larger plates. The Himalayas continue to grow right now because the Indian plate is being pushed into the Asian plate. Sometimes all the continents are pushed together to form a supercontinent, like Pangaea, but as convection currents in the mantle change, the supercontinents eventually break up into smaller continents again.
Water temp.
Is the water temperature affected by the hole in the ground?
Not that much heat is
Not that much heat is escaping through the hole to affect the water temperature at the surface.
Temperature
How hot is the core that you guys drilled into?
Since we are still in the
Since we are still in the crust, though about 1500 meters deep in it, the temperatures are probably between 110 and 120 degrees Fahrenheit at the bottom of this drillhole.
Drilling
I admire that this group of people take their time and go out to the middle of the ocean to get samples to help us figure out more about the world we live on. I have a few questions to clarify my understanding... what type of tools do you use to get from 3,600 meters of water to drilling into the lower oceanic crust? Can the tools that you have reach the mantle or core? What would happen if you did reach the mantle and/or the core? What types of samples would you find? Would molten material come out and if it did, would anything happen to the ocean? I hope all of your goals are reached! :)
Sophie
To learn about some of the
To learn about some of the tools we use to drill this deep, read this blog from a previous expedition: http://joidesresolution.org/node/1700. To learn about drilling all the way to the mantle, keep watching the JR blogs over the next two weeks. We will be writing about the "Mohole Project" the project geologists have been wanting to do to reach the mantle.
Another informative blog
Another informative blog about drilling is here: http://joidesresolution.org/node/1887
Just for clarification...
Hi!
What I gather is that the asthenosphere is tremendously far underground, and it since it has the consistency of Silly Putty, it probably would not be the most favorable drilling destination. So this means that drilling that far into the earth as well as actually drilling the asthenosphere would be horrendously difficult, and the goal of this current expedition is not to reach the asthenosphere, right? If so, then how deep are you really aiming to drill? Also, do you know temperature of the asthenosphere? Thank you and I hope you reach your goal whatever it may be! :)
Anita
Thanks, Anita! This hole was
Thanks, Anita! This hole was about was about 1500 meters deep already at the beginning of the expedition. The goal is to drill as deep as we can in the few weeks we have at sea, which may only be a couple hundred meters deeper, because it takes a long time to drill and bring up the cores from that deep. That would still be a ways (over 5000 meters) from the asthenosphere. The temperature of the asthenosphere varies from about 700 to 1600 degrees Fahrenheit; as you probably know it's hotter the deeper you go.
How Hot?
Hi, I was wondering how hot it is down there? I know that it is very hot down there due to the closeness to the core and I was wondering if you could feel the extreme temperature. Thanks.
-Turtle Boy
Since we are still in the
Since we are still in the crust, though about 1500 meters deep in it, the temperatures are probably between 110 and 120 degrees Fahrenheit at the bottom of this drillhole.
How deep?
I was wondering When you guys will get through the Lithosphere? When you guys get through it, will you guys stop and go back to the crust? Or will you guys keep on digging? Thanks.
-Turtle Boy
Hi Turtle Boy-We are still
Hi Turtle Boy-We are still only a small part of the way through the lithosphere and do not have enough time to drill very much deeper into it, so we will only be in the crust this expedition.
Sea Floor Spreading
Hi, I was wondering if you can actually see the sea floor spread. I know that it has a very slow pace but i was wondering if you guys had a camera on it to see it and then put it on super fast motion to watch it. I think that would be cool. Thanks.
-Turtle Boy
Sometimes when the seafloor
Sometimes when the seafloor spreads it causes earthquakes like the ones that caused the tragic disasters recently in Japan. We can see the results of seafloor spreading when that occurs, but we cannot see the seafloor spreading just by watching it because it is such a slow process.
Sophie A.
I admire that this group of people take their time and go out to the middle of the ocean to get samples to help us figure out more about the world we live on. I have a few questions to clarify my understanding... what type of tools do you use to get from 3,600 meters of water to drilling into the lower oceanic crust? Can the tools that you have reach the mantle or core? What would happen if you did reach the mantle and/or the core? What types of samples would you find? Would molten material come out and if it did, would anything happen to the ocean? I hope all of your goals are reached! :)
See the response to your same
See the response to your same comment above.
Question
How deep will you guys cut into the Earths crust? What kind of a drill do you guys use to cut through?
Curry is the word not bird!!!!!!!!!!!!!!!!!!!!!!!!!!!
We started at 1500 meters
We started at 1500 meters below the seafloor and we will drill as far as we can in the few weeks we are at sea, which will probably be only a couple hundred meters deeper. This blog shows what our drill bit looks like: http://joidesresolution.org/node/1887. Also, everybody knows that the bird is the word.
Drilling
Since your drilling to mantle Don't you have to have a special type of drill since it's so hot and hard.
From, Aaron
School of PCDS
We are drilling deep in the
We are drilling deep in the crust on this expedition, but are still far away from the mantle, so we do not need special equipment because of heat, but we do need special drill bits because the rock is very hard here.
The Sea Floor Spreading
Since you're drilling at were the sea floor is spreading have you some pillow basalt.
From Aaron
Pcds
Where we are currently
Where we are currently drilling is too deep for pillow basalts. They tend to be at the top of the ocean crust. The first expedition to drill this hole probably saw a lot of it, though.
Where?
Where are you drilling? What plates are you on? Is the process of where you are drilling sea floor spreading? collision?-HOTDOG
We are drilling off the coast
We are drilling off the coast of Costa Rica in the Pacific Ocean (visit here to see a map of where we are: http://joidesresolution.org/node/1745). The seafloor is spreading here, but at a rate that looks superslow to us, so there is no chance of collision.
Also, we are on the Cocos
Also, we are on the Cocos Plate in the Pacific. Sorry I missed that the first time.
Ocean Floor
How deep will you drill down into the oceanic crust? Will you ever hit molten material in the asthenosphere? -Sam
We are hoping to drill to
The hole was already 1500 meters deep when we started and we are hoping to drill as far as we can in few weeks we have at see, which may only be a couple hundred meters deeper. The asthenosphere is much deeper than that, and because it takes a lot of time to drill the seafloor, it would take many more expeditions to reach that deep.
Layers of the Earth
HI!!!! Are you able to drill into the Asthenosphere, if so, how far can you drill into the surface???????!!!!!!!!!!!!!! Please Reply!!!!
Sarah H.
Geologists have wanted to
Geologists have wanted to drill to the asthenosphere for as long as they have been drilling for research. It's called the Mohole project (I'll be writing more about that in a blog in a couple weeks). Because of time and money limitations, and because the asthenoshere is so intensely hot, no one has been able to drill that deep yet.
Core
Have you guys ever drilled to the core before or is it too deep?
-ELLEBOB
The core is too hot and too
The core is too hot and too deep to drill at least with the technology we have now. To date the JR has only drilled the crust, which if the Earth was an apple, would be the same as drilling just part of the way into the peel.