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Re: Post KT



I got an other article from V. Vajda and S. MacLoughlin (Fungal
Proliferation at the Cretaceous - Tertiary Boundary, Science, Vol. 305, 5.
March 2004, 1489). In this article can find Ir concentrations in samples. I
will write these here. (I measured from the diagramm.)
No. of sample   centimeter      Ir in ppb       Comments
19              - 2             0.4             No fungi up to 24. sample. 
Samples No. 7. - 14. and 18. are
also 0.4 ppb, 15. and 16. are 0.6.  
20              - 1.7           0.4
21              - 1.3           0.5
22              - 1             0.9
23              - 0.7           1.1
24              - 0.3           1.3             Fungal layer begin before 25. 
and finished before 26.
KT              0
25              0.3             3.3
26              0.7             4.1             No more fungi 
27              1               2.3
28              1.3             0.8             Up to 28. coal
29              1.7             0.3             Carbonaceous mudstone
30              2               0.3             Each other samples have 0.3 
ppb, too.  

What is showing these data?

1. Ir anomaly begin before KT (- 1 cm) and finished up to the end of coal
layer (1.7 cm after KT). Why isn't sharper? Why isn't suddenly jump up? A
big impact did it. A slow fallen (my theory)didn't. 
2. Fungal layer begin at KT layer but finish before the peak of the Ir
anomaly. Why?
3. The peak point of Ir concentration is 0.7 cm after KT. Why so late? How
many year are this late?

Endre Simonyi

At 15:52 2004.03.09. -0700, you wrote:
>
>This says the research is from the Swedish Research Council, but that
>site's in Swedish so I can't reference the original news release...
>This is almost a spooky scenario.
>
>
>http://www.astrobiology.com/news/viewpr.html?pid=13787
>
>The catastrophe that extinguished the dinosaurs and other animal species,
>65 million years ago also brought dramatic changes to the vegetation. In a
>study presented in latest issue of the journal Science, the
>paleontologists Vivi Vajda from the University of Lund, Sweden and Stephen
>McLoughlin from the Queensland University of Technology, Australia have
>described what happened to the vegetation month by month. They depict a
>world in darkness where the fungi had taken over.
>
>Its known that an asteroid hit the Yucatan peninsula in Mexico at the end
>of the Cretaceous Period. It left a 180 km wide crater and from the impact
>site tsunamis developed and the Caribbean region was buried in ash and
>other debris. The consequences of the asteroid impact were global. Vajda
>and her colleagues have previously studied the broad-scale changes in the
>New Zealand vegetation following the impact, but now they have
>dramatically improved our view of the timing of events.
>
>At the end of the Cretaceous the vegetation on New Zealand was dominated
>by conifers and flowering plants. Many of these species disappeared
>suddenly at the end of the Period and were instead replaced by fungal
>spores and fungal threads preserved in a four millimeter thick layer of
>coal. The layer coincides with fallout of iridium, an element rare in
>Earth's crust but which abounds in asteroids.
>
>"We have managed to reconstruct the event month by month, with a very high
>time resolution", says Vivi Vajda. During a very short period - from
>between a few months to a couple of years - the fungi and other
>saprophytes which live on dead organisms must have been the dominating
>life form on Earth. Atmospheric dust blocked the sunlight and led to the
>death of plants that are dependent on photosynthesis. 
>
>The layer of fossil fungi is followed by a 60 cm thick interval containing
>traces of the recovery flora, which re-established relatively quickly,
>ground ferns at first, followed after decades to hundreds of years by more
>diverse, woody vegetation.
>
>A similar layer of fungi and algae is known from a previous catastrophe
>which happened 251 million years ago at the Permian-Triassic boundary.
>This was an even greater mass extinction: about 90% of the existing
>species disappeared. Research will now focus on whether the similar
>biological signatures at these mass extinctions reflect similar causal
>mechanisms. 
>