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Published online 23 February 2009 |
Nature
| doi:10.1038/news.2009.112
Corrected online: 24 February 2009
News
'Dinosaur-killing' impact did not start global wildfires
Burnt oil and gas, not vegetation, may have caused the soot layer at the end of the Cretaceous period.
The impact of a huge asteroid or comet at the end of the Cretaceous period 65 million years ago is generally held responsible for the sudden demise of 60–80% of all species on Earth. But new results challenge the common idea that the extinctions were partly caused by global wildfires triggered by the violent impact.
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I imagine some saurian spirit chuckling to note "You primates may call us small-brained but we lasted hundreds of millions of year and we didn't wipe ourselves out."
Interesting. Another theoretical appendage of the impact theory now cast quite convincingly into doubt. And I find the reference to the proximity to "Mexico's largest oilfield" quite mysterious - surely the source rocks for this (present-day) hydrocarbon accumulation had barely been deposited, never mind matured enough for spontaneous combustion?
Given that many hydrocarbon deposits date from the Paleozoic era, it is not unreasonable to assume that an oil field may have been under the impact site, especially given the proximity of a known oil field to that site. As for "spontaneous combustion": Given the amount of heat released by the impact, the ignition any oil brought into contact with the atmosphere by the impact can harly be called "spontaneous".
The saurian spirit may indeed be chuckling, saying "You can see nothing of our fuel-burning civilization other than the pollution layer we left behind. We've saved you a seat...."
This proves that dinosaurs were intelligent beings and had installed oil-fired central heating world-wide. As they hadn't yet invented telescopes (glass being somewhat fragile in their claws) they weren't able to take preventive measures.
"dinosaur killing" is not because of any wild fires or climatic changes.It is just the part of development.Civilizations evolved and disappeared,likewise dinosaur-era evolved and disappeared.If the case would have been with wildfires even the evidences found now would have been burnt out then and there.
Amazing that is stated that it is incorrect to say that a meteorite impact caused mass-extinctions. This correction seems to me highly incorrect, because after all is said and done, the only demonstrable mass-extinction, -i.e. that of calcareous oceanic plankton (coccoliths as well as foraminifers)- coincides in all complete K-T boundary transitions exactly with the evidence for a major impact.
A possible source of hydrocarbons is methane dissolved in deep ocean waters and suddenly released in the course of a methane-driven oceanic eruption. This mechanism (unrelated to methane hydrates) was used to explain the extinction at the Permian-Triassic boundary (dx.doi.org/10.1130/G19518.1), but the arguments apply equally well to the K-T boundary. Cisowski (1990) mentions "the abundance of a methane byproduct (coronene)" at the K-T boundary.