These two periods of time were characterized by widespread peat (coal) deposits, great shifts in sea level as observed in cyclothems, and by continental glaciation. What was (were) the driving force (s) behind these great changes.
Hi Annette, Thanks for your input. What about the usefullness of plant megafossils?
Best wishes, Pual...
Hi Annette, Can you give us an exampe from your own research? Thanks. Best
wishes, Paul.
Hi Paul, I am recently working on Permian paleoclimate and palynology in the Karoo Basin, South Africa. The publications are available for download on my page. It works very well. Plant megafossils are mainly preserved in the coals itself, with the palynomorphs we can look also at the silt- and sandstone packages in between the seams.
Hi Annette, Yes, I can see that palynogy is a powerful tool in dealing with paleoclimate.Most of the best plant megafossils are preserved in the roof rocks of coal. However, they are also found in siltstones in coal-poor strata. The trunks of trees and even upright plant fossils can be found in sandstone. So one has to look in all the strata.Thanks so much for responding to my question. Best wishes, Paul.
Hi Paul, yes, in many cases you also find the plant fossils in the sand-/siltstone interlayers. In open pit mines and outcrops very useful. For palynology we mainly work with core material and thus the macrofossils are rarely discovered.
Best wishes, Annette
Hi colleague,
clays being my area of ecxelence these will be helpful in solving the problem not only from a climatic point of view but also to restore all paleogeographic history of your study area provided that your clays are of detrital origin (no diagenetic influence).
For marine sediments, isotopes are also very powerful tool in paleoclimate reconstruction. For example, oxygen isotope can be used to calculate the paleo-temperature of seawater. The oxygen isotope of conodonts or fish teeth is the best choice.
Dear Yanlong Chen,
Thank you so much for your answr on the use of oxygen isotopes for paleoclimatic reconstructions in marine-dominated strata. Sounds like a great tool! Best wishes, Paul.
I suggest you to use oxygen and carbon isotop. The oxygen isotope data constraints on the evolution of deep sea temperature and continental ice volume. Because deep ocean waters derived primimarily from cooling and sinking of water in polar regions, the deep sea temperature data also double as a time averged record of high latitude sea surface temperature. The deep sea carbon isotope data, on the other hand, provide insight into the nature of global carbon cycle perturbations and on first order changes in deep sea circulation patterns.
Hi Seydou, Very nice answer. It is very good advice, I think. Happy St. Patrick's Day! Paul.
Paul, the general nature of your question causes me to wonder if you've searched the literature? Paleoclimate reconstructions have been created for these time periods many times, using all of the tools listed in the previous responses as well as other tools, including various climate models. Some of the climate model simulations date back to the 1980's. I would use those with caution as climate models post 1999 are distinctly different in some key aspects. Nonetheless, they can still give you a general trend (just not useful specifics).
In general, when not using a climate model, one creates a paleoclimate reconstruction using the distribution of proxy data, which include: palynology (pollen, spores, fungi, dinocysts), microfossils (forams, nannos, radiolarian, silica flaggelates), paleosols, wood fossils, leaf size/shape/stomata, coals, red beds, aeolian deposits, lacustrine deposits, reptiles, evaporates, carbonates, isotopes (oxygen, strontium, TEX86, etc), depositional environment distributions, glendonites, tillites, and macrofossils (type, abundance, distribution, and specific hard material analysis such as bone analysis).
Determination of the driving forces requires the use of a climate model because those forces are typically outside of ones local area of interest. For example the growth of a mountain belt thousands of km away could impact the climate of your area. Similarly, solar insolation cycles can change the climate of specific areas but have no impact in others via it's connection to the monsoon system. As these are periods in which angiosperms had not yet developed, and the world was not fully covered in plants (as it is today), one must take the modified influence of precipitation recycling into account (one of the reasons the old models don't work as well). Also, this is a period in which super landmasses exist, and they are dominantly in the southern hemisphere - decidedly different from today - which means the circulation patterns of today are not applicable to that time period.
Are you trying to put together the climate of a specific area or are you trying to understand the global climate during those periods?
If you have well log data, try doing a frequency evaluation. There are numerous studies that have examined e.g., Milankovitch and other cycles from cyclicity in the log signals. One way to do it is via a STFT or a Walsh transform.
Hi Manika, Thank you for your response and your insightful suggestion. Best wishes, Paul Lyons.
Dear Paul
I recommend to check the Meyer (2007)A Review of Paleotemperature–Lapse Rate Methods for Estimating Paleoelevation from Fossil Floras, Reviews in Mineralogy and Geochemistry,v. 66, p. 155-171
Regards
Massih
http://rimg.geoscienceworld.org/content/66/1/155.full.pdf
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