[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Cosmic rays and the estimation of paleo-elevation

One hundred hours after it fell, the Allende meteorite was tested for
radioactive isotopes. The researchers detected emissions from a variety
of isotopes including K40, Al26, Co60, Na22, Mn54, Na24, Be7, Mn52, Co56,
Cr51.  Some of these isotopes were created by cosmic rays interacting
with the rock while it was in space. (K40 is also a "primordial" isotope,
which complicates things a bit).

If any of these isotopes decay to an "unusual" stable daughter element
(which would "stand out" in an isotopic analysis), then they might be
detectable in very old terrestrial rocks.  It would be interesting to
study surficial rocks collected from the peak of Mount Everest (29,000
feet) and see if the abundances of cosmic-ray caused stable daughter
isotopes is measurably higher than in surficial rocks at low elevation. 
If the idea has merit, it might be possible to create a graph of daughter
element ratios vs elevation.  This relationship might be used by
researchers who are studying ancient slip-slope faces, or perhaps even
applied to the study of ancient conglomerates.

Regarding how to sample:   It probably would be counterintuitive to
normal sampling technique.  A person collecting on Everest would look for
rock with the oldest surfaces.  A "good" sample would probably be highly


On Thu, 27 Jul 2006 07:56:30 -0700 (PDT) don ohmes <d_ohmes@yahoo.com>
> Me, I'm conglomeray-ted about thinking. Hope there is something OTC 
> for it, my doctor hates me.
> Insect wings might _possibly_ do it (low resolution), but a lot of 
> work would have to be done w/ extant animals first.
> Don
> ----- Original Message ----
> From: Phillip Bigelow <bigelowp@juno.com>
> To: dinosaur@usc.edu
> Sent: Wednesday, July 26, 2006 2:29:22 PM
> Subject: Cosmic rays and the estimation of paleo-elevation
> Does anyone know if extant high-elevation animals (say, Mountain 
> Goats)
> contain more C14 in their bodies than do extant low-elevation 
> animals
> (such as domestic sheep)?
> And:
> Are there any *stable* cosmic-ray-formed isotopes that might be 
> present
> in fossil bone?  For instance, archaeologists sometimes use lichens 
> to
> date rock surfaces.  Following that rationale, could isotopic ratios 
> be
> used to determine if a rock's surface was exposed to a 
> high-elevation
> environment (with more cosmic rays)?
> I'm thinking about conglomerates.
> <pb>
> --