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Author | Topic: Geologists and dating (India Basins Half a Billion Years Older Than Thought) | |||||||||||||||||||||||||||||
Joe Meert Member (Idle past 5709 days) Posts: 913 From: Gainesville Joined: |
Ok, I've been involved in some research over the past few years wherein my group has been thinking about a 500 million year revision in the age of a basin in India. That's a big deal in geology, but we finally went ahead and published our data. Creationists tend to accuse geologists of being brainwashed into accepting the status quo. Had we accepted the status quo, we would have never gone ahead and published these data, but to me, they begged to be published and they begged to challenge the status quo. So, the next time someone accuses scientists of being set in their ways, tell 'em it ain't so:
http://news.nationalgeographic.com/...0710-india-basins.html Cheers Joe Meert Edited by Joe Meert, : No reason given. Edited by Adminnemooseus, : Added "(India Basins Half a Billion Years Older Than Thought)" part to topic title.
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AdminNosy Administrator Posts: 4754 From: Vancouver, BC, Canada Joined: |
Thread moved here from the Proposed New Topics forum.
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Coyote Member (Idle past 2136 days) Posts: 6117 Joined: |
This thread isn't getting much traffic because it is normal for science to improve theories as the data requires. Theories become more accurate with each such change, and science does not fear changes of this type.
Business as usual.
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The Matt Member (Idle past 5571 days) Posts: 99 From: U.K. Joined: |
Interesting findings! Thanks for sharing.
Most YECs will generally not be interested unless you decide that something is younger than previously thought
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Brian Member (Idle past 4989 days) Posts: 4659 From: Scotland Joined: |
quote: You do know that Creationists will say you only published because the six basins are dated older, if they dated younger then you wouldn't have published, I can hear them now. They may also point out that such a huge discrepency in dating may point to the worthlesness of scientific dating techniques. They will find some way to undermine your good, honest work. Thanks for the link.
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Percy Member Posts: 22505 From: New Hampshire Joined: Member Rating: 4.9 |
From the National Geographic article:
National Geographic writes: Meert, the study leader, said the discrepancy between the new study and older ones is easy to explain: Initial age estimates were done in the early days of geochronology, when methods for dating rocks and sediments were not as accurate. "Not as accurate" is quite an understatement for an error of nearly 100%. How were the basins originally dated? --Percy
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3 |
I'm also curious: how was it originally dated? How was it dated this time? Why did this result in such an astonishing discrepancy?
Also: what implications does this have for the credibility of other dates?
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Chiroptera Inactive Member |
I'm curious about that, too. I'm guessing that the original dates were based on dating of a few (too few) samples of younger intrusions or younger material that was later incorporated into the sediments.
Added by edit: I will also add that I am getting the impression is that the initial dates were confirmed by the presence of relatively advanced metazoans. In fact, confirmed older dates will have some exciting implications about the evolutionary history of metazoan life. This is on my list of things to investigate further. Exciting stuff! Edited by Chiroptera, : No reason given. Speaking personally, I find few things more awesome than contemplating this vast and majestic process of evolution, the ebb and flow of successive biotas through geological time. Creationists and others who cannot for ideological or religious reasons accept the fact of evolution miss out a great deal, and are left with a claustrophobic little universe in which nothing happens and nothing changes. -- M. Alan Kazlev
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Joe Meert Member (Idle past 5709 days) Posts: 913 From: Gainesville Joined: |
The original ages were K-Ar ages on glauconite and Fission track ages on sedimentary rocks. Basically, you are talking about throwing something at the rocks and hoping something good comes out of it. It was also based on the assertion by Indian geologists that the basins were all of the same age and all were Neoproterozoic to Cambrian in age due to the lack of fossils. In short, it was a guess that became a 'firm age' in the minds of many people working in the area. The new estimates come from two lines of evidence (1) Samples of sedimentary rock yield zircons that are inherited into the rock. The oldest zircon can be sometimes used to infer the age of the rock (i.e. the sample should contain zircons of all older material). In this case, our samples came from a region next door to a huge (>50,000 sq km) granite-rhyolite terrane of 770-900 Ma age (well-dated). Our samples yielded no detrital zircons younger than 1020 Ma. So we could make an assumption that the lack of these 770-900 Ma zircons mean that the sediments are older than the granite rhyolite province. The second piece of evidence came from a study we made in 2006 on a kimberlite pipe that intruded the lower part of this basin. We obtained an age of 1073 Ma on the kimberlite, but more importantly the paleomagnetic data from the kimberlite was identical to some early studies on the sedimentary rock. We did a detailed paleomagnetic study and, sure enough, the kimberlite pmag directions and our sedimentary rock directions were identical. we concluded that the combination of (a) no young zircons and (b) the matching of pmag directions signified the basin was about 500 Ma older than originally thought.
FYI: There has been much e-mail debating between Indian scientists, myself and several paleontologists regarding this find. One Indian paleontologist labeled me as 'anti-Darwin' for proposing that the metazoan record may extend well back into the Neoproterozoic! Me, anti-Darwin. well, now I've heard it all. Cheers Joe Meert
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New Cat's Eye Inactive Member |
I just wanted to say:
quote: And:
quote: /me tips his hat.
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JonF Member (Idle past 198 days) Posts: 6174 Joined: |
Any possibility of a PDF reprint?
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Joe Meert Member (Idle past 5709 days) Posts: 913 From: Gainesville Joined: |
Sure, no problem. I can link to the 'corrected proofs' on my website and you can get it there
http://www.clas.ufl.edu/users/jmeert/malone.pdf By the way, the Natl. geo article lists me as first author, but it is actually my MS student (graduated and now working on a Ph.D in Iowa) who wrote the bulk of the paper (and did all the hard work) Cheers Joe Meert
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peaceharris Member (Idle past 5626 days) Posts: 128 Joined: |
Hi Joe,
Few questions about Fig 14 in your paper before we start a discussion: Are the Concordia plots corrected by removing the common Pb that was present initially when the zircon crystallized? If yes, how did you determine the initial Pb content?Can you give us the raw data of the amount of all isotopes of Uranium and Pb in each sample? Thanks.
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Joe Meert Member (Idle past 5709 days) Posts: 913 From: Gainesville Joined: |
Yes, a common lead correction was made for the samples. You can read about the correction in the paper by Williams (1998, referenced in the paper). This correction is now integrated into our spreadsheet and coupled to Ludwig's isoplot program. Do you really want raw data for each of the 270 grains?
Cheers Joe Meert Williams (1998)
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peaceharris Member (Idle past 5626 days) Posts: 128 Joined: |
Please provide the paper by Williams and the raw data. Without the raw data and the correction algorithm you used, I would not be able to start a discussion.
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