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The role of meteors in the mass extinction events



Good day to all listmembers,

I'd like to ask what's the current general opinion on the role of meteors in 
the mass extinctions events (and not just the KT one)? Also, I'like to make 
myself clear about the possible correlation of meteor craters and recognized 
extinction events in the geological past. In David M. Raup's book "Extinction: 
Bad Genes or Bad Luck?" appear some interesting data (published back in 1990). 
I've already mentioned these on the list before. Firstly, there's a short list 
of all strata containing iridium anomalies (as for 1990 state of knowledge), 
I've updated the time estimates:

Frasnian (Devonian) 375 mya

Callowian (Jurassic) 161 mya

Cenomanian (Cretaceous) 94 mya

KT boundary 65.5 mya

Eocene (Tertiary) 34 mya

Miocene (-"-) 12 mya

Pliocene (-"-) 3 mya

+ Pleistocene (Quaternary) 12kya

Were any other strata containing iridium layer found from 1990 until today? 
Were some of the listed revisited and/or rejected? Were already found meteor 
impact craters that could be attributed to these dates (esp. 161, 94, 3 mya) ? 

Author also compares the age of the layers with then-known impact craters and 
mass extinction events. 4(3) of them seems to "match" time-wise with the Ir 
layer or ME event (values updated):

Siljan (Sweden) 52 km (in diameter), 377 mya (?, Frasnian/Famenian)

Charlevoix (Quebec) 54 km, 342 (+- 15) mya

Manicouagan (Quebec) 100 km, 214 mya (200 Triassic/Jurasic - not likely)

Manson (Iowa) 38 km, 74 mya (65.5 KT event, not likely)

+the ones that can be assigned to a smaller extinction events:

Clearwater (Quebec) 36 and 26 km, 290 (+- 20) mya (299 Carboniferous/Permian, 
not likely)

Popigai (Russia) 100 km, 35.7 (+-0.2) mya (34 Eocene/Oligocene)

Ries and Steinheim (Germany) 24 and 3.8 km, 14.3-14.5 and 15 mya resp. (late 
middle 
Miocene extinction, langhian)

Chicxulub wasn't properly known back in 1990, so author does mention it only 
briefly in the text. My question as for the list above is: are there any new 
finds of craters that would correlate with the dates above and is there any 
revision given the new chronostratigraphy, approach, methods used etc.? Thank 
you in advance, Vladimir

________________________________
Mgr. Vladimir Socha
Hradec Kralove, Czech Republic

http://dinosaurus.bloguje.cz
http://klubdinosauripaleontologie.unas.cz