shadron
Philosopher
- Joined
- Sep 2, 2005
- Messages
- 5,918
Ok, im having a problem grasping the huge difference in the age of the Oceans and how Tectonics account for it with Subduction.
Now i am no expert, but from my reading and reviewing of this Oceanic map... (http://geology.about.com/library/bl/maps/blseafloorage.htm)
I cant for the life of me understand how these reds zones and green zones came to be no older then 120.4 Mil years old, and as young as 9.7 Mil years old.
In my unscientific thought process shouldnt one side of colliding/separating Tectonic plates differ in age then the opposing side its colliding/separating from? An example i am looking at of what i mean can be seen in the chart provided above. By glancing at the chart it appears as if the Pacific Plate is moving away from the Scotia plate, Nazca plate, Cocos Plate and Noth American Plates. I say this because of the difference in age with the Oceans residing on the Pacific plate and all plates stated above. The Scotia, Nazca, cocos and North American plates all seem to have much younger Oceans, which to me suggest these plates are moving apart by coming out from underneath the Pacific plate revealing new and much younger oceans.
My question now is, why for 1,500+ miles does the Pacific plate have new younger oceans coming from its fault line with the "North American Plate" ect. heading westward (Towards Japan)?
Shouldnt one plate be immediately much older from another at there fault lines depending on which one is going under or coming out from the other? I see this strange affect at just about every Tectonic Plate Fault line on the map. I thank you, ahead of time, anyone who is able to give me an answer to this question.
In case it isn't plain, there are three sorts of plate boundaries (discussed above) - subduction, spreading and transform. The ones you mention are spreading, not subduction. Most subductions (but not all) occur where sea floor meets continents, because the continental plates are lighter and tend to override the sea floor, particularly along the US/Canadian Pacific coasts; in fact, it is busy swallowing the Pacific spreading joint, which is causing the Cascades and the San Andreas faults. Along that subduction joint, the continental plate (US and Canada) is much older than the sea floor disappearing underneath.
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