Geology of New Guinea

As we learned in the last two week's lab, the tectonic history of New Guinea is not far off from the tekonic orogany involving the North American plate. At the rate that the subduction is going, New Guinea will collide with Australia and become one large continent much like North America.

The Sumatra plate is the early stage of plate subduction. What is occurring is Sumatra is riding up to over a plate of oceanic lithosphere which is connected to another plate of continental lithosphere along down the road. The second stage falls with Timor. This is where a plate of continental lithosphere and more oceanic lithosphere have already subducted half of the Australian plate along with its oceanic lithosphere. Timor is situated on top of the oceanic lithosphere that is riding on top of the Australian plate. The final stage of the New Guinean tectonic history has the Australian continental lithosphere being broken up by an ophiolite. The continental lithosphere connected to the other side of the ophiolite is continuing to subduct the oceanic lithosphere falling behind it. The water surrounding New Guinea is very, very shallow, showing how close the two continental lithospheres really are. Technically, when looked at on the opposite side of the world, Brevard College would sit on the space of continental lithosphere that is entrapped between the ophiolite and the oceanic lithosphere pushing under it.

In terms of the Appalachian Mountains, the Piedmont plate pushed onto the Blue Ridge plate pushing the Appalachian Mountains up. The last step was the coastal plan plate which pushed the Appalachians up as high as or possibly higher than the Himalayas today. This all happened during the tekonic and allaghenian oroganies.

An easier way to think of all this happening is to compare it to a big mack truck and a tiny Volkswagen. The mack truck is the Australian plate and the Volkswagen is New Guinea. The Australian plate is so big, that when it collides with New Guinea, New Guinea will not have a change at all. New Guinea will ride over the edge of the Australian plate and soon, New Guinea and Australia will be one, with New Guinea being on top.

After doing this exercise, I can understand how everything works now. It is really interesting to actually see what is going on with plate subduction.