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Re: k/t boundary, dust and CO2
On Fri, 18 Nov 1994, 718 wrote:
> due to a computer glitch, this message which preceded the other one
> on dust got bounced back to me instead of going to the list:
> as a geochemist i am fascinated by what the k/t boundary event would
> have caused (assuming a meteorite impact for a minute). impacting a
> meteorite in carbonate rocks of the yucatan would drastically increase
> the CO2 in the atmosphere. if you look at the geochemistry involved,
> this produces a major INCREASE in the solubility of calcite, which may
> explain the crash of the nannoplankton discused by a recent poster
> (sorry i deleted the message without noting the name).
> similarly, the meteorite would itself volatolize significantly,
> adding consider quantities of other gases, like SO2, H2S, CO2, etc.
> particulates might include things like heavy metal oxides of Fe, Ni,
> Cu, Zn, etc, but also significant quantities of As, Se, Hg, etc.,
> not to mention the Ir we all know and love. From the added silicates
> and phosphates in the meteorite, if it were a chrondritic type, we
> could expect significant increases in H4SiO4 and H3PO4, meaning that
> silica would also likely increase significantly in solubility.
> what does this mean for organisms? it means they must work MUCH
> harder to precipitate their shells if they have to signficantly
> change the solubility of the mineral species rather than just change
> it slightly as is the case in most situations today. even for
> the dinos life might have been very difficult. if H3PO4 increases,
> apatite solubility increases. vertebrates already have a significant
> problem precipitating hydroxyapatite because it is soluble in body
> fluids. if its solubility increases significantly in water, the
> solubility problem in the body is more severe, meaning the animals
> might have experienced very "spongy" bones or their young may not
> have been able to form bone. (this last is speculation on my
> part that flowed as this post flowed.)
> food for thought anyway...
Note that target rock had an enormous sulfur content which may have
produced some acid rain, but more importantly probably blocked sun light
and produced some green house gas effects. The geochemistry of the event
is being heavily studied. An entry to the literature can be found in the
extended abstracts of the Snowbird Conference last Feb. (Published by
Lunar and Planetary Institute). Also a few papers in this year's Geol.
Soc. Amer. Annual Meeting Abstracts vol. (from last month).