Hi
Regarding the possible London Clay microtektites. I have just received some
more data from the finder. It doesn't look good as I report below. I hope you
appreciate that I am simply reporting information as I receive it and in hind
sight maybe I should have held back a bit. These spherules were, however,
reported in the very reputable Geologists' Association Magazine, and this is
how I came to hear about them.
These spherules were analysed in 1994 by Glan Izett of the USGS. The
spherules did not contain any Radiogenic 40Ar and it was thus concluded that
the spherules had zero geologic age. The Major element electron micro-probe
analyses of the glass-like spherules gave the following results:
SiO2 31.92 31.57 32.30
Al2O3 16.00 15.74 15.96
MgO 5.60 5.83 5.65
FeO 0.26 0.27 0.27
CaO 40.22 40.23 40.06
Na2O 0.26 0.27 0.27
K2O 0.71 0.76 0.78
MnO 0.85 0.92 0.93
BaO 0.07 0.10 0.05
TiO2 0.61 0.65 0.63
TOTAL 96.51 96.37 96.89
The high amount of CaO and SiO2 certainly does not favour tektite glass. It
is interesting, however, that the proposed source crater (Silverpit Crater)
would be within the Upper Cretaceous Chalk (around 96% CaCO3).
The collector of the spherules, Michael Daniels, states 'Those that are
familiar with my site activities, the way I conduct my researches, from digging
out the accumulations usually from foreshore exposures, then the method by
which the pockets are rendered down here to acquire searchable residues, all
would unquestionably confirm the veracity of my contentions concerning both the
remarkable Naze biota, and the various unusual minerals, other items, not only
the tektites, in my collection.'
I am simply reporting the facts as I recieve them - I will leave you to draw
your own conclusions on these data. Certainly the analyses are far from
favourable and the zero geologic age will prove difficult to overcome.
Personally I would like to visit the site to follow-up.
Regards, Aubrey
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