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Author Topic:   Correlation Among Various Radiometric Ages
RAZD
Member (Idle past 1405 days)
Posts: 20714
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Joined: 03-14-2004


Message 61 of 61 (376987)
01-14-2007 4:54 PM
Reply to: Message 56 by Percy
01-10-2007 8:01 AM


Joe Meert
Sorting through my bookmarks I also found this:
Consistent Radiometric dates
by Joe Meert
Created Jan 2000
Updated January 6, 2004 (links fixed, added)
One of the main objections to radiometric dating
quote:
Here are a few examples in the recent literature of radiometric age determinations on the same rocks (using different isotopic methodsa).
{table}
The ages of the Fen Complex (A,B) are on two separate dikes within the Fen Complex. Not only are their ages similar, but the direction of magnetization in the rocks is also identical and indicates that Oslo, Norway was located at about 30 degrees south at the time. This is an important consideration. In order to refute the ages, ye-creationists must not only explain how three different isotopic systems (with different decay constantsa and chemical behavior) all gave the same age and the same magnetic direction. It is also not trivial that the magnetic direction in these rocks indicates that Norway has moved northward following the emplacement of these rocks.
The Madagascar results are equally intriguing since they are from two regions on the island. These basalts (and gabbros) are thought by conventional geologists to have formed as Madagascar moved over the Marion hotspot during the Cretaceous. The basalts overlie continental sandstones containing Mesozoic fossils and are overlain by limestones with Cretaceous-age fauna. The first two ages are from southern Madagascar and the bottom two are from the northern part of Madagascar. According to paleomagnetic data from these rocks (Torsvik et al., 1998), northern Madagascar passed over the hotspot before southern Madagascar in perfect agreement with the geochronologic data. Furthermore, these ages all fall within a time period when the Earth was in a long period of no magnetic reversal (called the Cretaceous Long Normal). Indeed, if the ages are correct, then the paleomagnetic data should all be of a single polarity (and normal). That is exactly what Torsvik et al. (1998) found.
...
The following table outlines the closure temperatures of the various minerals used in the Carion study along with their ages. Details regarding closure temperature studies can be found in McDougall and Harrison (1999).
{table}
Note that the ages of the minerals yields a cooling-curve that is consistent with the experimentally-derived closure temperatures of the isotopic systems. Had decay rates not been constant, then we might expect to see a gross discordance of mineral ages in this study. Instead, we see a very nice cooling curve for this magma. The story doesn't end there however! This study also included a look at the paleoposition of Madagascar at the time this rock cooled. This is done through the study of paleomagnetism. Madagascar was thought to be a part of a larger supercontinent called Gondwana during this time period. A reference curve for Gondwana has been developed that basically traces the paleoposition of Gondwana during the time interval from 550-475 Ma (Meert et al., 2001a, 2001b).. If Madagascar was indeed a part of this supercontinent, then the paleomagnetic directions for Madagascar should be identical to the directions from other continents that make up Gondwana. Since magnetic minerals in the Carion rocks lock in their directions at temperatures between 550-450 C (in this study), then the age of magnetization is about 508 +/- 11 Ma. The position of Madagascar should match up with other 510 Ma directions from Gondwana---and they do!. Here, as above, we have many independent verifications for the age of the Carion pluton that are internally self-consistent. This presents a serious problem for those who might advocate random decay rates for the different isotopic systems.
He also has a webpage where he takes on the "RATE" group
More Faulty Creation Science from The Insitutute for Creation Research
quote:
This rock (from Madagascar) would give a K-Ar age of 1997 +/- 4 Ma. The problem is that it contains excess argon (note the extremely old ages at either end of the 'saddle'. Ar-Ar analyses clearly shows the presence of excess argon and the presence of excess argon makes dating of this sample difficult. Austin KNOWS that olivine is not suitable for precision K-Ar dating and he KNOWS that Ar-Ar dating would reveal the excess argon, but he will only perform K-Ar because it is guaranteed to give a spurious result. There is no science in this proposal and the results are guaranteed before conducting the experiments. I argue that $50,000 could be more wisely spent feeding hungry children in third world countries rather than perpetrating scientific fraud!
The usual high quality work from Joe. If anyone wants to debate these ages with Joe he does post here as "Joe Meert" - see:
http://EvC Forum: Joe Meert Topic Index -->EvC Forum: Joe Meert Topic Index
Enjoy.

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This message is a reply to:
 Message 56 by Percy, posted 01-10-2007 8:01 AM Percy has not replied

  
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