http://www.eurekalert.org/pub_releases/2007-03/cu-mot030107.php Apparently, a huge hole in the oceanic crust reveals the mantle beneath.
Offtopic, but have you seen the discovery channel stuff they put on youtube, like Man vs. Wilds (or whatever it's called)?
It's all fake anyway. I wonder what the cameramen are doing while he's squeezing water from elephant shit.
Wouldn't get your hopes up for anything too spectacular. Its just gonna look like rock. Interesting non the less. I'd like to know what they find out about this.
Its so near to the spreading ridge that the rock can only be a few million years old, not billions. I doubt an impact crater is the cause. The rocks they are talking about should be buried several km under other rock. I'm not sure any impact could uncover them. I'm wondering about oversteepening of the ridge & a massive landslide uncovering the lower layers. I'm not sure how feasible this is though. I wish they'd make more information available on the website about the site they are studying and what they already know.
As I understand the formation is far older than the time since the last ice age. Besides warming-cooling is cyclic. http://www.nature.com/nature/journal/v345/n6278/abs/345800a0.html
I wonder what kind of sea-life is down there, could be some strange stuff if it has been there a long time.
The Nature article states that this is located less than 200 km from the Mid-Atlantic Ridge, that constantly pours out new crust. But the question is if this is "a sample of sub-oceanic mantle" or "a relict of sub-continental mantle, which was left behind during the opening of the equatorial Atlantic, and was then tectonically uplifted to its present position." The rift that split Pangaea created the Atlantic Ocean about 180 million years ago. Somehow this research is related to the "Classroom@Sea Project" because the article ends by directing you to their website for future news at: http://www.noc.soton.ac.uk/gg/classroom@sea/JC007/
The location where they are going to be working is just at the spot where the mid-Atlantic ridge makes a sharp turn so my guess is the crust has probably slipped off the mantle. The original crust that was on top of the mantle might be east of the mantle now still being pulled off, I love rock,LIMESTONE,DOLESTONE,SANDSTONE,COMGLOMERATE,SHALE,DUNITE,GABBRO,GRANITE,HORNBLENDE,PORPHYRY,DIABASE,BRECCIA,SLATE,MARBLE,GNISS,SCHIST,ALL OF THEM EVEN THOSE RARE MANTLE ONESPlease Register or Log in to view the hidden image! .
That's a pretty thin layer of crust around there anyways - less than 5 km - with plates still being pulled apart from the rift that broke Pangaea: pulling apart the North American Plate from the Eurasian Plate. This area has already been extensively studied. There's a lot of recycled continental crust there and it's a "hot spot." The whole area is called the St. Peter and St. Paul Fracture Zones. All these fracture zones belong to the category of trans-oceanic faults, crossing the axial zone of the Mid-Atlantic Ridge and its flanks and the floor of the oceanic basins adjacent to the ridge: "We think there is 'channeled flow' in the asthenosphere from Fernando de Noronha toward the nearest part of the mid-Atlantic Ridge, the St. Peter and St. Paul Rocks." http://www.mantleplumes.org/P^4/P^4Chapters/MorganP4ElectronicSupp1.pdf. http://unesdoc.unesco.org/images/0010/001063/106318E.pdf. Nor is this the only area on Earth where there is exposed mantle, as the article states: http://losmirones.esteticas.unam.mx/legislacion/archivos/or/37669.pdf. See also: Bastien, T.W., and Craddock, C., 1976, The geology of Peter I Island, in Hollister, C.D.,Craddock, C., et al. eds., Initial reports of the Deep Sea Drilling Project, Volume 35:Washington, D.C., U.S. Government Printing Office, p. 341-357
Gros Morne National Park: Situated on the west coast of the island of Newfoundland, the park provides a rare example of the process of continental drift, where deep ocean crust and the rocks of the earth’s mantle lie exposed. I might have a sample of that or something exposed a little further south, I got a few one is like black with white weathering, another is blue with white weathering and I can not remember what the other one looks like inside but it is weathered brown. All I know about them is what they look like though, they catch my eye because of the way they weather.
Gros Morne is beautiful. The section that's exposed is a large hill about a thousand feet high and a quarter mile long or so. We climbed it while we were there, but back then I wasn't into geology so I wasn't very fascinated by the rocks - wish I knew more then. We just looked at it as an odd barren hill amongst all the beautiful encompassing forest in the park. There's no vegetation on it.
I've been doing a bit of detective work here... The rock exposed here is serpentinite, which is a metamorphic rock. The parent material of serpentinite is peridotite, which is the residue left over when partial melting has occured, so from this I'm assuming there was once basalt etc on top of the section which has since been removed. If the rock is old enough, it could have cooled sufficiently so that decompression melting did not occur. Peridotite is denser than serpentinite: 3.3g/cm3 compared to 2.7 g/cm3 so metamorphosis would cause some adiabatic uplift, going some way to explain why the rock is exposed. It also expands by 40% upon metamorphosis- I wonder if this would lead to faulting & fracturing of any crust that was above it. It seems the timing of the metamorphosis is going to be relevant here.
