Posted by: paulgarner | October 9, 2009

Pyritized fossils, eruption plumes and magma ascent rates

Now how about that for a snappy title?

Life beyond the blogosphere has been rather full of late, but I just have time today for a round up of some recent journal articles.

The discovery of pyritized fossils at six new localities in the Ordovician Lorraine Group of New York State is described in the October edition of Geology (Farrell et al 2009). The localities span 54 km of outcrop and occur within thin mudstone horizons representing single depositional events. The reported geochemical data, along with the near-absence of disarticulated and fragmented skeletal material, suggest rapid burial of these organisms with subsequent precipitation of iron sulphides on and in the decaying carcasses. Such studies have the potential to help creationists further understand the processes involved in fossil preservation throughout earth history and especially during the global flood.

Another paper in Geology reports the first measurements of the turbulent velocity field of a volcanic column based on an extensive reevaluation of video and photographs of the 18 May 1980 eruption of Mount St. Helens in Washington State (Andrews and Gardner 2009). Over the years, creationists have shown a lot of interest in developments at Mt St Helens (e.g. Austin 1986) and this paper adds to our knowledge of how the famous eruption proceeded.

Seismic shocks felt by residents near Chaitén volcano, in northern Patagonia, just 24 hours before a devastating eruption of rhyolitic magma on 1 May 2008 suggested rapid rates of magma ascent. This has been confirmed by petrological and experimental data reported in Nature (Castro and Dingwell 2009) which indicate that the Chaitén magma ascended with velocities on the order of one metre per second. The implied transit time from storage depths greater than five kilometres to the near surface is about four hours. Rapid ascent rates have previously been documented for kimberlitic (Kelley and Wartho 2000), granitic (Brandon et al 1996) and basaltic magmas (Demouchy et al 2006) and it seems that rhyolites fit the same pattern.

Elsewhere on t’internet, Todd Wood has been busy making my frequency of posting look very inadequate. He’s been writing on anything and everything from advice to students looking for credibility as creationists, the new Creation film, homology in Notch proteins, Anchiornis and Ardipithecus. He’s also been winning friends and influencing people with his thoughts on evolution (see the follow ups here, here and here). Do drop by Todd’s blog and take a look.

Finally, thanks to the person who recently took the trouble to send the following message:

You Christians are killing the Earth with your insanity and lies. Your god is a lie, smoke and mirrors. Your God is more evil than your Satan because god  wants eternal pain for those in hell. I’m afraid the only way to save the Earth is to exterminate Christianity and all dualistic religion.

It warms my heart to know that the old fashioned virtues of tolerance and fairmindedness are still alive and well.

References

Andrews B. J. and Gardner J. E. 2009. Turbulent dynamics of the 18 May 1980 Mount St. Helens eruption column. Geology 37(10):895-898.

Austin S. A. 1986. Mt St Helens and catastrophism. Institute for Creation Research Impact Article Number 157.

Brandon A. D., Creaser R. A. and Chacko T. 1996. Constraints on rates of granitic magma transport from epidote dissolution kinetics. Science 271(5257):1845-1848.

Castro J. M. and Dingwell D. B. 2009. Rapid ascent of rhyolitic magma at Chaitén volcano, ChileNature 461:780-783.

Demouchy S., Jacobsen S. D., Gaillard F. and Stern C. R. 2006. Rapid magma ascent recorded by water diffusion profiles in mantle olivine. Geology 34(6):429-432.

Farrell Ú. C., Martin M. J., Hagadorn J. W., Whiteley T. and Briggs, D. E. G. 2009. Beyond Beecher’s Trilobite Bed: widespread pyritization of soft tissues in the Late Ordovician Taconic foreland basin. Geology 37(10):907-910.

Kelley S. P. and Wartho J.-A. 2000. Rapid kimberlite ascent and significance of Ar-Ar ages in xenolith phlogopites. Science 289(5479):609-611.

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