Paleonet: Microfossils in organic-rich mudstones

Tue Jan 11 16:29:45 UTC 2022

Hi Øyvind,

We have two Xradia machines here at the Univeristy of Portsmouth (510 and
520 Versa units), so could potentially run some test samples to see what
the capabilities are.

https://www.port.ac.uk/research/research-centres-and-groups/zeiss-global-centre

Happy to chat about it.

All the best,
Tony.

On Tue, 11 Jan 2022 at 15:58, Øyvind Hammer <oyvind.hammer at nhm.uio.no>
wrote:

> As I said, the technology is not yet quite there, but almost. What is
> needed is an instrument that can both handle relatively large samples
> (cm-scale) and at the same time have resolution better than a couple of
> microns. New-generation instruments such as the Zeiss Xradia are
> approaching this capability.
>
> Here, we have an "old" Nikon Metrology XT H 225 ST, and with samples of
> size e.g. 1x1x1 cm I can clearly see large features of forams inside, but
> not details. I would also be interested to hear if anyone has managed to
> count forams in rocks with e.g. a Zeiss Xradia, nanoCT or synchrotron (the
> latter would of course not be practical for routine work).
>
> Øyvind
>
> ________________________________________
> From: Paleonet <paleonet-bounces+oyvind.hammer=nhm.uio.no at paleonet.org>
> on behalf of Thomas, Ellen <ellen.thomas at yale.edu>
> Sent: 11 January 2022 15:49:04
> To: PaleoNet
> Subject: Re: Paleonet: Microfossils in organic-rich mudstones
>
> Hi Øyvind,
> Iike Dani, I am very interested in your methods – of course, I realized
> this was theoretically possible, but did not think it would actually work
> in the near future. That would be a very great step forward.
> Ellen Thomas
>
> From: Paleonet <paleonet-bounces+ellen.thomas=yale.edu at paleonet.org> on
> behalf of Øyvind Hammer <oyvind.hammer at nhm.uio.no>
> Reply-To: PaleoNet <paleonet at paleonet.org>
> Date: Tuesday, January 11, 2022 at 03:56
> To: PaleoNet <paleonet at paleonet.org>
> Subject: Re: Paleonet: Microfossils in organic-rich mudstones
>
> ... the technology is perhaps not yet quite there, but will be very soon:
> In our microfocus CT we can usually see both calcareous, agglutinated
> (siliceous) and pyritized forams inside shales and mud rocks. We are
> already using this to screen samples before disaggregating, but the
> resolution on cm-scale samples is not good enough for species
> identification.
>
> With the new generation of "zoom" CT, we will soon be able to count and id
> forams in mud rocks efficiently and completely, with no damage to the
> specimens, and with precise information on their 3d distribution.
>
> Øyvind Hammer
> Natural History Museum
> University of Oslo
>
> 11. jan. 2022 03:34 skrev "Thomas, Ellen" <ellen.thomas at yale.edu>:
> Dear all,
>
> In my experience all processing methods have (at least some) negative
> effects on the foraminifera in the processed sediments, with more fragile
> species breaking and/or partially dissolving.  I have recently had
> reasonable success with the liquid nitrogen method (Remin et al., 2012, A
> new method of rock disintegration and foraminiferal extraction with the use
> of liquid nitrogen [LN2]. Do conventional methods lead to biased
> paleoecological and
>
> paleoenviromental interpretations? Marine Micropal 86-87, 11-14). For very
> indurated sediment I have used the oil-method, which leads to considerable
> breakage, but at least gets a reasonable number of specimens out: break
> sediment in pieces, dry, soak in some sort of mineral oil for a few days,
> decant, heat in soapy water, decant.
>
>  Best
>
> Ellen Thomas
>
>
> From: Paleonet <paleonet-bounces+ellen.thomas=yale.edu at paleonet.org> on
> behalf of "Walter.Etter at bs.ch" <Walter.Etter at bs.ch>
> Reply-To: PaleoNet <paleonet at paleonet.org>
> Date: Monday, January 10, 2022 at 02:33
> To: "paleonet at paleonet.org" <paleonet at paleonet.org>
> Subject: Paleonet: Microfossils in organic-rich mudstones
>
> Dear paleonetters,
>
> does anybody of you have experience using surfactants for microfossil
> processing?
>
> The disintegration of mudstones rich in organic material is difficult.
> Standard procedure with 5-8% peroxide and subsequent washing over a
> sieve-stack (I use 250•m, 125•m, 63•m) sometimes reduces the amount of
> sediment to only one quarter (from 200g to 50g) which makes it an almost
> impossible task to pick the microfossils. For a further reduction of the
> clayey material various methods were suggested such as cooking in sodium
> carbonate which leads to a modest but still unsatisfactory reduction.
>
> In the past we used the slightly acidic surfactant «Bradophen»
> (Benzozoniumchloride) and obtained very good results. Alkaline surfactants,
> however, were not effective. Since «Bradophen» is no longer available, I
> tried using «Rewoquat» (Imidazoliniumquat) which is also a slightly acidic
> surfactant and reduces the residue to less than 10%. But of course we do
> not know what mechanism is behind that, and if certain microfossils are (at
> least partially) dissolved. Therefore I highly appreciate any
> suggestions/recommendations regarding the use of surfactants or other
> methods for the reduction of the clayey material.
>
> With best wishes for the New Year, Walter
>
> Dr. Walter Etter
> Naturhistorisches Museum
> Kurator Geowissenschaften
> Augustinergasse 2
> CH 4001 Basel
>
> Telefon +41 61 266 55 63
> Fax +41 61 266 55 46
> walter.etter at bs.ch<mailto:walter.etter at bs.ch>
> www.nmbs.ch<
> https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.nmbs.ch%2F&data=04%7C01%7Cellen.thomas%40yale.edu%7C1f093c992a294326b66d08d9d4e03215%7Cdd8cbebb21394df8b4114e3e87abeb5c%7C0%7C0%7C637774881822722699%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=rQMw8Ay0C6Y0SQlEwgkLKuwxEK0ODpTadVJ4hd4jjRw%3D&reserved=0
> >
>
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