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Author Topic:   Geologists and dating (India Basins Half a Billion Years Older Than Thought)
Joe Meert
Member (Idle past 5758 days)
Posts: 913
From: Gainesville
Joined: 03-02-2002


Message 1 of 93 (474770)
07-10-2008 9:26 PM


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.

Replies to this message:
 Message 3 by Coyote, posted 07-11-2008 12:37 AM Joe Meert has not replied
 Message 4 by The Matt, posted 07-11-2008 6:08 AM Joe Meert has not replied
 Message 5 by Brian, posted 07-11-2008 7:40 AM Joe Meert has not replied
 Message 6 by Percy, posted 07-11-2008 8:22 AM Joe Meert has not replied
 Message 7 by Dr Jack, posted 07-11-2008 11:49 AM Joe Meert has not replied

  
AdminNosy
Administrator
Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 2 of 93 (474781)
07-10-2008 10:57 PM


Thread moved here from the Proposed New Topics forum.

  
Coyote
Member (Idle past 2184 days)
Posts: 6117
Joined: 01-12-2008


Message 3 of 93 (474791)
07-11-2008 12:37 AM
Reply to: Message 1 by Joe Meert
07-10-2008 9:26 PM


Business as usual
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 5620 days)
Posts: 99
From: U.K.
Joined: 06-07-2007


Message 4 of 93 (474803)
07-11-2008 6:08 AM
Reply to: Message 1 by Joe Meert
07-10-2008 9:26 PM


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 5037 days)
Posts: 4659
From: Scotland
Joined: 10-22-2002


Message 5 of 93 (474809)
07-11-2008 7:40 AM
Reply to: Message 1 by Joe Meert
07-10-2008 9:26 PM


quote:
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
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: 22606
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.9


Message 6 of 93 (474812)
07-11-2008 8:22 AM
Reply to: Message 1 by Joe Meert
07-10-2008 9:26 PM


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: 07-14-2003


Message 7 of 93 (474835)
07-11-2008 11:49 AM
Reply to: Message 1 by Joe Meert
07-10-2008 9:26 PM


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?

This message is a reply to:
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Replies to this message:
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Chiroptera
Inactive Member


Message 8 of 93 (474844)
07-11-2008 1:50 PM
Reply to: Message 7 by Dr Jack
07-11-2008 11:49 AM


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 5758 days)
Posts: 913
From: Gainesville
Joined: 03-02-2002


Message 9 of 93 (477288)
07-31-2008 10:03 PM


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

Replies to this message:
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New Cat's Eye
Inactive Member


Message 10 of 93 (477302)
08-01-2008 1:52 AM
Reply to: Message 9 by Joe Meert
07-31-2008 10:03 PM


Nothing to add to the topic
I just wanted to say:
quote:
Bravo! Joe
And:
quote:
Congrats on the find. Thanks for all the hard work
/me tips his hat.

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JonF
Member (Idle past 246 days)
Posts: 6174
Joined: 06-23-2003


Message 11 of 93 (477335)
08-01-2008 9:08 AM


Any possibility of a PDF reprint?

Replies to this message:
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Joe Meert
Member (Idle past 5758 days)
Posts: 913
From: Gainesville
Joined: 03-02-2002


Message 12 of 93 (477389)
08-01-2008 6:04 PM
Reply to: Message 11 by JonF
08-01-2008 9:08 AM


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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Replies to this message:
 Message 13 by peaceharris, posted 08-06-2008 1:33 AM Joe Meert has replied

  
peaceharris
Member (Idle past 5674 days)
Posts: 128
Joined: 03-28-2005


Message 13 of 93 (477661)
08-06-2008 1:33 AM
Reply to: Message 12 by Joe Meert
08-01-2008 6:04 PM


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.

This message is a reply to:
 Message 12 by Joe Meert, posted 08-01-2008 6:04 PM Joe Meert has replied

Replies to this message:
 Message 14 by Joe Meert, posted 08-06-2008 12:38 PM peaceharris has replied

  
Joe Meert
Member (Idle past 5758 days)
Posts: 913
From: Gainesville
Joined: 03-02-2002


Message 14 of 93 (477683)
08-06-2008 12:38 PM
Reply to: Message 13 by peaceharris
08-06-2008 1:33 AM


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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Replies to this message:
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peaceharris
Member (Idle past 5674 days)
Posts: 128
Joined: 03-28-2005


Message 15 of 93 (477714)
08-06-2008 9:06 PM
Reply to: Message 14 by Joe Meert
08-06-2008 12:38 PM


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.

This message is a reply to:
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Replies to this message:
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 Message 17 by Joe Meert, posted 08-07-2008 3:43 PM peaceharris has replied
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