What's the big deal about continental shelves? The five countries bordering the Arctic (U.S, Canada, Denmark who administers Greenland, Norway and Russia) have exclusive right over mineral deposits extending to 200 nautical miles from their coasts. This zone can be extended if any country can prove that their continental shelves extend to a distance more than 200 miles. Russia is now claiming just that. It is saying that the Lomonosov ridge which is an underwater linear block of continental crust aligned roughly NE-SW is a natural extension of its continental shelf. Preliminary estimates suggest that the ridge could yield about 10 billion barrels of hydrocarbons.
Plate tectonic theory has been used to explain the geological evolution of terrains, but this is probably the first time it has been called upon to resolve a brewing political crisis.
IBCAO-NOAA-NGDC.
In early Tertiary period (about 50 million years ago) the north Atlantic spreading ridge propagated northward (dotted purple line and arrow). This cause the continental shelf of Eurasia to rift and split apart. This rift evolved into a oceanic spreading ridge known as the Gakkel ridge (spreading shown by yellow arrows). The Lomonosov ridge is a linear block of Eurasian continental shelf which split and moved NW to its present position. Russia asserts that its Siberian continental shelf extends naturally as the Lomonosov ridge. The point of contention is highlighted by a red arrow next to the label Russia. Is there is geological continuity of terrains there? Plate tectonic theory suggests that the ridge was moved there into position and juxtaposed against the Siberian shelf. Recent seismic data show that as the ridge approaches Siberia it deepens and there are buried faults in the deeper sediment between Siberia and the Lomonosov ridge, a finding that supports tectonic theory. Denmark and Canada can probably make a similar claim on it's side of the Lomonosov ridge.
But why should that matter? Currently reality should take priority. Even if the ridge was originally somewhere else and stuck on to the Russian shelf later by plate movements, doesn' t that make it a natural extension of the Russian shelf. The law of the sea doesn't say which type of geological process should cause the extension of the shelf. I have a feeling Denmark will also be able to show that the Lomonosov ridge is attached to their shelf. As warming clears more Arctic ice, plate tectonic theory will have plenty to say on the complicated energy politics of the Arctic ocean.
I am and Arctic geologist, working on a plate tectonic reconstruction of the Amerasian Basin in the Arctic Ocean. Consequently my field season is spent on ice breakers in the Arctic Ocean and for the past few summers I have been involved with the "mad dash" to do bathymetric mapping of this region.
ReplyDeleteEvery country on the planet at this time is collecting scientific data of their continental shelves (or whatever they have as borders)in order to define their ESC or extended continental shelves. Countries that border the Arcitc are trying to define theirs as well. This is not a mad dash to exploit the Arctic but to gather information in a very data poor environment in order to define the extent of the continents, which is very tricky in a region whose tectonic history is so vague and very controversial among tectonic geeks who care about such things. However the U.S. is also mapping the Atlantic and Pacific coasts in order to define those continental extents as well.
The only boundary that is not under dispute in the Arctic Ocean is the one between U.S. and Russia which was negotiated in the 80's. You are correct in saying that the tectonic history, or where the plates used to be, is indeed irrelevant to a country's claim, however when trying to define "continent" vs. "oceanic" crust the tectonic history is important, hence the exercise.
As far as the ice pack goes, all I can tell you is that there are good ice years and bad ice years. In 2006 the ice was so intense that we were stranded just north of Barrow for 5 days and were hindered from gathering good data for most of the 45 day cruise. Yet last year the ice had all drifted/blown toward Greenland and we had only first year ice in the Amerasian Basin to about 85 north to contend with while our collegues in the Eurasian Basin were unable to continue because of the huge pressure ridges that had built up. One should not get too excited about year to year fluctuations and as a geologist remember that the only thing one can count on about planet earth is change.