Yellowstone caldera

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In order to further clarify the last significant wide spread eruption of Yellowstone caldera, perhaps bore holes out in Kansas, Nebraska etc. would be useful in dating. For example, 1000 ft etc. is associated ~ with how many years? Also directly dating such wide spread significant ash layer. Has an ~600,000 year scale eruption already occurred at ~present site, for significantly less than ~600K yrs cycle? http://en.wikipedia.org/wiki/Yellowstone_caldera" [Broken]
 
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  • #2
Evo
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In Kansas, rocks dating at ~400 million years at at ground level.
 
  • #3
sylas
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In Kansas, rocks dating at ~400 million years at at ground level.
Ah! That explains the local political situation.

(ducks and runs)

Back on topic... the big eruption at yellowstone about 640,000 years ago left a layer of ash called the Lava Creek Tuff, covering what looks like about half the continental USA. It will have been eroded away in some locations, so it might not appear in every hole you dig, but I think it's easily found and dated right across much of the USA. I don't have details, though.

Cheers -- Sylas
 
  • #4
Xnn
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Has an ~600,000 year scale eruption already occurred at ~present site, for significantly less than ~600K yrs cycle? http://en.wikipedia.org/wiki/Yellowstone_caldera" [Broken]
While the time between the latest and previous full scale eruptions was roughly 600,000 years, going back further in time, the frequency is usually less often. Some times as much as 2 million years. So, a full scale eruption is not "over due".

On the other hand, there have been many smaller eruptions at greater frequency. The latest being about 13,000 years ago.
 
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While the time between the latest and previous full scale eruptions was roughly 600,000 years, going back further in time, the frequency is usually less often. Some times as much as 2 million years. So, a full scale eruption is not "over due".

On the other hand, there have been many smaller eruptions at greater frequency. The latest being about 13,000 years ago.
There was the largest increase in C14 on record during the Younger Dryas Cooling event (13000 years ago) which coincides with the Yellowstone Caldera eruption.

http://cio.eldoc.ub.rug.nl/FILES/root/2000/QuatIntRenssen/2000QuatIntRenssen.pdf [Broken]

This change is apparently the largest increase of atmospheric 14C known from late glacial and Holocene records (Goslar et al., 1995). Hajdas et al. (1998) used this sharp increase of atmospheric 14C at the onset of the YD as a tool for time correlation between sites. What are the possible causes for this large increase in atmospheric 14C? Geomagnetic variations are not a likely cause, since these generally act on a much longer time scale (i.e. millennia). Amongst others, Bjorck et al. (1996) and Goslar et al. (1999) postulate that the increase in 14C at the start of the YD is caused by a decrease of the CO2 exchange between the atmosphere and ocean, because of stagnation in ocean circulation (i.e. 14C changes as an effect of climate change). If the deep-water formation would weaken or even cease, this would reduce the atmosphere ocean exchange of CO2, thus effectively increasing the atmospheric 14C content.

My comments:
1) In the last 5 years there are multiple papers that provide evidence of abrupt changes to the geomagnetic field. An abrupt drop in the geomagnetic field for a thousand years would explain the Younger Dryas cooling.
2) C14 could be explained by changes in ocean currents hypothesis has been disproved Recent detailed analysis of ocean circulation indicates the North Atlantic Drift current is not reduced during the Younger Dryas. In addition, there are other periods where the North Atlantic Drift current is reduced and there is no increase in C14.
Inverse Relationship of Solar Minimums and Volcanic Eruptions
There is (see papers below) an inverse relationship of sunspot number (solar activity) and volcanic eruptions. During the Maunder and Dalton minimums there are significantly more and larger volcanic eruptions. When the sunspot activity is high there is less volcanic activity. This curious correlation continues throughout the planetary data. It appears the strength of the mechanism (Whatever is causing the increase in volcanic activity) is related to how fast the sun changes from a high number of sunspots to a low number of sunspots.

As some authors have noted that the increase in volcanic activity correlates with abrupt drops in the planet’s temperatures, in addition to correlating with a deep solar minimum.

Originally it was proposed and some authors still propose without quantitative analysis that the abrupt long term drop in temperature was caused by the volcanic eruption however a major eruption only cools the planet for a few years.

These very cold periods are greater than a hundred years so the mechanism that is cooling the planet must be different, however, what is causing the volcanic eruptions could also be causing the planet to abruptly cool.

“Volcanic eruptions and solar activity” by Richard Stothers

http://adsabs.harvard.edu/abs/1989JGR....9417371S

The historical record of large volcanic eruptions from 1500 to 1980 is subjected to detailed time series analysis. In two weak but probably statistically significant periodicities of about 11 and 80 yr, the frequency of volcanic eruptions increases (decreases) slightly around the times of solar minimum (maximum). Time series analysis of the volcanogenic acidities in a deep ice core from Greenland reveals several very long periods ranging from about 80 to about 350 yr which are similar to the very slow solar cycles previously detected in auroral and C-14 records. Solar flares may cause changes in atmospheric circulation patterns that abruptly alter the earth's spin. The resulting jolt probably triggers small earthquakes which affect volcanism. (My comment. This proposed mechanism is not correct.)
http://adsabs.harvard.edu/abs/2002AGUFMPP61A0298A
The Role of Explosive Volcanism During the Cool Maunder Minimum
The Dalton Minimum was a period of low solar activity, named for the English meteorologist John Dalton, lasting from about 1790 to 1830.[1] Like the Maunder Minimum and Spörer Minimum, the Dalton Minimum coincided with a period of lower-than-average global temperatures. The Oberlach Station in Germany, for example, experienced a 2.0° C decline over 20 years.[2] The Year Without a Summer, in 1816, also occurred during the Dalton Minimum. The precise cause of the lower-than-average temperatures during this period is not well understood. Recent papers have suggested that a rise in volcanism was largely responsible for the cooling trend.[3]
http://www.pnas.org/content/101/17/6341.full#otherarticles

Bipolar correlation of volcanism with millennial climate change by Ryan Bay, Nathan Bramall, and Buford Price
 
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