Hi Doreen,
thank you for your comments. You have been able to date the phytolith
concentrates? Or did you date the organic carbon fraction? In general
during pollen treatment the silica is solved away, so I actually don't
know if there are phytoliths in the record. However, if it is
possible to date phytolith cocentrates, than it is certainly something
I'm very interrested in, because in the semiarid environment I'm
working in, there are much better chances for them to be preserved
than for pollen.
I'd be very interrested to hear some more about it!
Best wishes
Christiane
Dr. Christiane Singer
Johann Wolfgang Goethe-Universität
Institut für Archäologische Wissenschaften
-Seminar für Vor- und Frühgeschichte-
D-60323 Frankfurt am Main
Tel.: +49 69 798-32112
Quoting Doreen Bowdery <[log in to unmask]>:
> continuing from Christiane and Chris Prior
>
> In general phytoliths (biogenic silica) are going to be smaller than
> pollen grains in any sediment. For my purposes very organic (ie,
> tropical rainforest) material sediments would be processed in the
> first instance by deflocculation to remove clay, followed by HCl
> (15%) and then H2O2 warm bath treatment until all or most of the
> reaction has finished, with intermediate distilled H2O washing,
> before flotation with NPT at 2.25-2.28 sg. Time consuming but it
> makes for clean, easier scanning of the many <15 micron phytoliths I
> encouter. This method has been used on samples submitted for AMS.
> NPT is preferred to the health hazardous Zinc bromide which gives a
> marginally cleaner float.
>
>
> Doreen Bowdery, PhD, Visiting Fellow
> School of Archaeology and Anthropology, Bdg 14
> The Australian National University
> Canberra ACT 0200 Australia
> Phone 6125 4772
>
> -----Original Message-----
> From: The archaeobotany mailing list
> [mailto:[log in to unmask]] On Behalf Of Dr. Christiane
> Singer
> Sent: Tuesday, 14 August 2007 8:46 PM
> To: [log in to unmask]
> Subject: pollen concentration
>
> Dear all,
>
> I am currently working on an organic rich clay deposit from the
> Euphrates valley. AMS-dating of pollen seems to be the only way to
> get any reliable age control, but as so far I did not manage to
> receive sufficiently pure pollen concentrates.
> The methods I have been using were: the standard methods (Faegri and
> Iversen 1989) + heavy liquid separation with Sodium Polytungstate +
> sieving and density solution with 1.3 sg following Vandergoes and
> Prior 2003 and Newnham 2006. But still there is a lot of non-pollen
> material.
>
> Is there anybody out there who knows how to produce nice pollen
> concentrates without too much other residues, or has experience with
> the matter?
>
> Best wishes
>
> Christiane Singer
>
>
> Dr. Christiane Singer
> Johann Wolfgang Goethe-Universität
> Institut für Archäologische Wissenschaften
> -Abt. Vor- und Frühgeschichte-
> D-60323 Frankfurt am Main
>
> Tel.: +49 69 798-32112
>
|