Re: Re siberian (Deccan) traps

["Tim Donovan" <msdonovan66@hotmail.com>]

Ken Carpenter wrote:

> Everyone's criticism of Frank's statement have all focused on his last 
> hyperbole, rather than his criticism of the sloppy thinking behind some of 
> the stories about impacts. One has only look at David Raup and the impact 
> periodicity as a classic example of seeing what you want. As has been 
> pointed out several times, there is no periodicity, even in Raup's own 
> data. As for the Chatterjee reference, that appeared in the Proceedings of 
> the Godwanan Dinosaur Symposium (Memoirs of the Queensland Museum, 1996). 
> He states that either the Deccan Trap basalts are the effects of the shock 
> wave propagating through the earth from the Chicxulub impact

 If that were true, neither is relevant to extinction since Deccan 
volcanism began 1 Ma or so before the K-T.


OR that there was an impact in what he calls the Shiva Crater off the west 
coast of India. He even states that this crater is larger than the 
Chicxulub. How can he know the size of the crater if he isn't even sure it 
is one?

  I understand Koeberl doubts it is. Years ago Chatterjee identified the 
K-T boundary in a putative impact layer (yielding iridium and shocked 
quartz)which he attributed to Shiva, just below the initial outpouring of 
lava at Bara Simla Hill. This impact layer, he wrote, dwarfed all others 
known, and indicated that Shiva triggered both the Deccan lava and the mass 
extinction. Later, however, when it became clear that dinosaurs persisted in 
younger, intertrappean layers, he said that Deccan volcanism and Shiva 
occurred by coincidence at about the same time. The K-T boundary shifted to 
an iridium horizon at Anjar, yet Prsad recently noted that Cretaceous 
fossils e.g. ostracods, occur stratigraphically above that horizon too.


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