Scientists use fossils to discover the ancient equator

Dec 17, 2012
Credit: University of Western Ontario

(Phys.org)—Researchers at Western University have discovered where the equator was "precisely located" 450 million years ago, which is an important breakthrough for paleontologists and planetary scientists, as well as private and public mineral resource companies. The findings have been published in the journal Geology and were highlighted in today's Editor's Choice section of Science.  
 
Jisuo Jin and Phil McCausland from Western's Department of Earth Sciences led an international research team that successfully traced a 6,000-kilometre stretch of fossils which proved the Ordovician equator ran through Northern Greenland, Manitoba (Canada), Utah and Nevada. The Ordovician geologic period, the second oldest of six of the Paleozoic Era, began 488.3 million years ago, following the Cambrian period, and ended 443.7 million years ago.

"If you consider the polar magnetic regions, you would have found those regions located in quite a different place 450 million years ago. And the equator, consequently, was located in quite a different place too," explains Jin. "North America has rotated approximately 90 degrees since the Ordovician. What is North today would have been East." 

"Because there are no hurricanes, there is no severe disturbance in the sea at moderate depth, so the sediment remains consistent for millions of years," says Jin. "By tracing fossils and , we were able to locate the precise location of the Ordovician equator."

According to Jin, locating past latitudes is vital to understanding anything that's happened historically to the Earth, geologically.

"If you want to predict the occurrences of anything from to barrier reefs, you need to know the latitude," offers Jin. "By precisely mapping and orienting the , we will have a good starting point to explore and better understand the of the planet, as well as the distribution of its various natural resources."

Jin says while this is an important finding for scientists, mineral resources companies will also find this discovery advantageous.    

"If you can find the ancient equator, you can map all the latitudes, and then you can predict what kind of minerals, rock, or petroleum resources exist and where they are located," says Jin. "For example, the famous Tyndall stone used for so many public buildings in Canada occurs only along the ancient equator from some 450 million years ago."

Jin says an all-important factor to the discovery was the fact that today there are no hurricanes within 10 degrees latitude of the equator. This equatorial hurricane-free zone can potentially be recognized in the fossil record of undisturbed marine deposits.

McCausland adds another determining dynamic is the fact that ancient Ordovician geography is based on permanent magnetic compass directions recorded in rocks of that period.

"These frozen-in-time paleomagnetic directions give us a good estimate of where the ancient polar regions were, but only if the Earth's magnetic field behaved then like it does now – as a kind of giant bar magnet."

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More information: For a downloadable map, please visit communications.uwo.ca/comms/pdf/jin_map.pdf .

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User comments : 5

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that_guy
5 / 5 (2) Dec 17, 2012
The photos at top should be better captioned. It took me a minute to realize that the first photo is a hurricane map to illustrate the incidence of modern hurricanes to show that the equator tends to be free of them.

I imagine the second map is meant to illustrate the landmass/equatorial zones during the era 450mya?
El_Nose
5 / 5 (2) Dec 17, 2012
Wow your comment was REALLY insightful -- I might not have read into the photo and article to a degree to establish that connection.

At least in regard to the top map.
Lurker2358
1 / 5 (3) Dec 17, 2012
Sigh*

What a meaningless study.

If this was the ancient equator, then obviously every place between that line and the modern line had the same opportunity to be "special," somewhere along the way, so why do you care about this one line?

Seems like completely false science, unless there was a pole shift of that magnitude.

So-called continental drift would have had all of the land and sea between that line and the modern equator roughly equally affected by being at the equator at one time or another. Infact, by the time you rotate that in 3-d, half the Earth would have been in there at one time or another...

Oh yeah, some of the strongest hurricanes/cyclones on record in both the Atlantic and the NW Pacific have happened very close to the equator.

Interpreting past cyclone behavior over these alleged time scales, based on 120 years of modern records and about 30 years of modern satellite records, is just silly.
Allex
5 / 5 (4) Dec 17, 2012
Sigh*

What a meaningless study.

Sigh*

What a meaningless comment from a layman without any special knowledge, experience or credentials whatsoever. The article states the approximate time frame in Ordovician, around 450 mln years, not

at one time or another
.

Just because the goal of this study has nothing to do with your personal insignificant life doesn't mean it is meaningless. It has scientific value as well as future profit gains.

The reason for this study was stated as to
"understand the evolutionary history of the planet, as well as the distribution of its various natural resources".

Is reading the whole article really so hard? -_- Or did you just write this comment to share with us your personal irrelevant opinion?
Sherrin
3 / 5 (2) Dec 18, 2012
I agree with Thatguy ... the diagrams should have been appropriately captioned. Lazy Physorg.

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