Asteroid may have killed dinosaurs quicker than scientists thought
"The previous data that we had ... actually said that they were different in age, that they differed by about 180,000 years and that the extinction happened before the impact, which would totally preclude there being a causal relationship," said Renne, who studies ties between mass extinctions and volcanism.
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“Geologist [I'm Climate Change]”
Since: Mar 07
#1 Feb 13, 2013
The Deccan traps actually bracket the age of the Chixculub impact.
The red soils in the old (N) part of the deccan topping the basalt traps formed between eruptions contain dino bones & eggshells. Obviously no extinction there even local (although a few would probably have been fried by the flow fountain event(s).
The red soils in the young (S) part of the Deccan traps record mammal bones & teeth and have absolutely no dino bits in them. Obviously these are POST extinction deposits.
The important bit here is that the Deccan flows themselves are the result of ponding of magma from the rising mantle plume which sits in a disc @ the base of the crust. The release mechanism as in the younger Columbia river plateau in the Basin & range is "crustal relaxation", a response to Rebound/long duration mercalli X (r/lx) megathrust earthquakes such as the S. Andaman (2004) central Chile(2010) and Tohoku,Japan(2011)to give modern examples, which relax both the descending plate and the overriding plate. The margin here would be the Tethys margin (approx Tibetan region of present day).
The result is that each flow would most likely record an r/lx event that relaxed the crust over the Deccan region triggering a flow event... so why important?
The reason is that the Chixculub impact would have produced a seismic shock large enough to have broken every megathrust on Earth @ the time. The result is that the r/lx affecting the Indian plate would have triggered an immediate basalt flow from the Deccan traps basalt plateau during the time immediately after (a few hours), the impact. The flow would have been erupting during the fallout & "dust in orbit stage" time of darkness that shut down much of the land plant based ecosystem that would have starved out the large Dino food chain based on herbiovores.
The result is a flow dating exactly the the K/T boundary mass extinction that would also have a high Os/Ir spike as a result of dust incorporated into the molten magma and over vent perched lava pond (about the size of a large lake).
How about that one for timing constraints.
One such flow appears to have in fact been logged in the Deccan traps and appears to heve resulted in a counter theory of Os/Ir spikes coming from magmatic sources...(approx mid 1980s or so... A ramble through the old journals should be enough to locate the flow forming the REAL K/T boundary & Chixculub impact event.
Have a nice day: Ag
#2 Feb 18, 2013
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