| Back-Scattered Electron Microscopy (BSEM) -- a tool for the study of graptolites Piotr Mierzejewski |
| ___________________________________________________________ Graptolite Net | Graptolites & Graptoliters | Relationships between graptolites | Rhabdopleuroidea | Cephalodiscoidea |
| PORTAL OF GRAPTOLITES AND PTEROBRANCHS SPONSORED BY "M.M. PLUS M." SZTANDARY |
| The 1970's saw the application of the scanning electron microscopy (SEM) to graptolite studies. First SEM studies of graptolitic material were published in Poland by Roman Kozłowski (1971) and in Great Britain by Barry Rickards et al. (1971). The conventional mode of SEM use is an invaluable tool for examining graptolite morphology and fine structure. These conventional three-dimmensional SEM images are obtained by measuring the secondary electron signal. |
| ______________________________________________________________________________________ Edited by Piotr Mierzejewski, the Count of Calmont and Countess Maja Anna Korwin-Kossakowska 2004 |
If the back-scattered electron signal is recorded an image with mean atomic number
contrast is produced. Recently, Bernd-D. Erdtman and Yuandong Zhang (2004) applied
the Back-Scattered Electron Microscopy (BSEM) technique to study graptolites. They
wrote:
" On some specimens, carbonized periderm tissues are finely preserved and coalified
to a black color, which results in a rather sharp contrast with the lighter micritic-clay
matrix. If these specimens were coated for SEM examination, these structures would
be completely covered by gold or palladium and consequently indiscernible and would
no longer be available for light microscope investigation, unlike those 3-dimensional
parts which can be well observed and studied through scanning electron microscopy.
For this reason, we attempted examination of selected specimens without coating
through SEM by Back Scatter Electron Imaging, a technique available in the Technical
University of Berlin (SEM brand name: Hitachi S-2700)."
" The normal SEM pictures of the specimens were unsatisfactory as the structures
visible under light microscope could not be discerned, but the simultaneous BSEM
images were surprisingly clear and informative. " " ...BSEM images illustrate both the
chemical compositional differences on the surface layer and the surface morphology of
the sample. On our BSEM pictures of Psigraptus jacksoni, the carbonized fuselli are
marked as dark lines, whereas the rock matrix is brighter because of the dominance of
silicon and heavy elements. The surface morphology of those field, where the periderm
has broken off and only films have remained, has also been illustrated in the BSEM
images (...)."
contrast is produced. Recently, Bernd-D. Erdtman and Yuandong Zhang (2004) applied
the Back-Scattered Electron Microscopy (BSEM) technique to study graptolites. They
wrote:
" On some specimens, carbonized periderm tissues are finely preserved and coalified
to a black color, which results in a rather sharp contrast with the lighter micritic-clay
matrix. If these specimens were coated for SEM examination, these structures would
be completely covered by gold or palladium and consequently indiscernible and would
no longer be available for light microscope investigation, unlike those 3-dimensional
parts which can be well observed and studied through scanning electron microscopy.
For this reason, we attempted examination of selected specimens without coating
through SEM by Back Scatter Electron Imaging, a technique available in the Technical
University of Berlin (SEM brand name: Hitachi S-2700)."
" The normal SEM pictures of the specimens were unsatisfactory as the structures
visible under light microscope could not be discerned, but the simultaneous BSEM
images were surprisingly clear and informative. " " ...BSEM images illustrate both the
chemical compositional differences on the surface layer and the surface morphology of
the sample. On our BSEM pictures of Psigraptus jacksoni, the carbonized fuselli are
marked as dark lines, whereas the rock matrix is brighter because of the dominance of
silicon and heavy elements. The surface morphology of those field, where the periderm
has broken off and only films have remained, has also been illustrated in the BSEM
images (...)."
BSEM micrograph
published by Zhang and
Erdtmann (2004) showing
Psigraptus jacksoni
Rickards & Stait, 1984
from the Tremadocian of
NE China.
__________
Zhang, Y. and Erdtmann, B.-D. 2004.
Tremadocian (Ordovician) biostratigraphy
and graptolites at Dayangcha (Baishan, Jilin,
NE China).
- Paläontologische Zeitschrift 78 (2), 32-
354.
published by Zhang and
Erdtmann (2004) showing
Psigraptus jacksoni
Rickards & Stait, 1984
from the Tremadocian of
NE China.
__________
Zhang, Y. and Erdtmann, B.-D. 2004.
Tremadocian (Ordovician) biostratigraphy
and graptolites at Dayangcha (Baishan, Jilin,
NE China).
- Paläontologische Zeitschrift 78 (2), 32-
354.
