Paleocene Sea level cycles?

  1. We have discussed sea level yoyo's from the Pleistocene ice age of which it is suggested that it balances with the ice volume paced on the poles. So all of a sudden a study pops up (courtesy of the author), Dr Madeleine Briskin:

    Briskin, M, Fluegeman R, 1990, Paleocene Sea Level Movements with a 430,000 Year Quasi-Periodic Cyclicity, Palaios V-5 p 184-198

    So you have cyclic sea level changes but supposedly no ice sheet to exchange the water volume with. The conclusion, barring an ice sheet yoyo, to tie the sea level changes to changes in the Earth's geometry caused by the Milankovitch eccentricity cycle is not supported by a mechanism. Anybody?
     
    Last edited: Jan 8, 2008
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  3. jim mcnamara

    jim mcnamara 1,492
    Science Advisor
    Gold Member

    Um, what view - by that I mean what changes- specifically exactly measured or calculated geometric changes? Are there reviewed articles with supporting data for this notion? Notice the use of the word "notion", not hypothesis. I do not have JSTOR access, so I cannot see the bibliography.
     
    Last edited: Jan 8, 2008
  4. As far as I can judge, an important part of the sea level cycle implies the changing ratio between coastal to deeper water single cell organism. The same technique I have seen being used here: see chapter 6 Eustatic sea level rise

    Edit: futhermore it may be noted that we may have had an event, known as melt water pulse 1A, which also implied a quick sea level rise lacking evidence of a clear source. See this thread

    Furthermore the speculation of earth geometry changes related to eccentricity, again, is for the account of the authors. The only thing that matters is how accurate the sea level fluctuation has been identified/calculated.
     
    Last edited: Jan 8, 2008
  5. baywax

    baywax 2,215
    Gold Member

    Hi Andre. I feel the same way about using "continental rebound" as an explaination for sudden drops in sea level around the same time as the "melt waterpulses" are being claimed to have been taking place. The confusion is evident when you consider that I was surveying for 10,000 year old evidence of human habitation at 500 feet above sea level. This survey was based on the "continental rebound" theory. While at the same time there was underwater archaeology going on 120 feet below sea level in search of the same evidence of human habitation at 10,000 yBP.

    One may be able to use "continental rebound" or "tectonic rebound", for that matter, as a model for what you are trying to explain. The continental rebound or continental depression would not have to be caused by ice fields but could be cause by varying pressures, currents and densities of the mantle being influenced by the effects of the Milankovitch eccentricity cycle (over time).
     
  6. Well let's say that to climatologists and astronomers we might as well live on a solid rigid rock that undergo all kind of orbits and cycles. Geographist and geologist would probably tend to focus on the whereabouts of the inside and outside of the Earth respectively, seeing a complex set of shells, dynamically reacting tor all kind of thermodynamic processes. Who would focus out to see a complex set of shells, dynamically reacting to all kind of thermodynamic processes, behaving as multiple interacting gyroscopes undergoing all kind of orbits and cycles?
     
  7. baywax

    baywax 2,215
    Gold Member

    Yes you have to take every influence into account . Deciding that one factor contributes to the repeated changes in sea level is a risk and highly unlikely.
     
  8. (Glaciation?) Cycles all around this time 200.000 years

    Isotopic Evidence for Glaciation During the Cretaceous Supergreenhouse

    Of course the 200,000 years period is nowhere near any Milankovitch cycle. What's going on?
     
  9. baywax

    baywax 2,215
    Gold Member

    Is there a proximity cycle where we get closer to the sun then further away? Or even closer to Jupiter then further? Also, are the larger planets contributing to our temperature by way of a changing proximity of the earth to them or a fluctuation of temp. on those planets?
     
  10. That planetary interaction is one of the causes for the Milankovitch cycles, especially the eccentricity cycle, which appears pretty stable at around ~400,000 years, as it appeared visible as early as the Cambrian. In the least eccentric orbit there is little variation in climate but at the max eccentricity seasons may be more intens or a lot less, depending on the precession (~21ka) and obliquity cycle (~41). Anyway that's all way to slow for us to notice during a lifetime.
     
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