All samples were analysed using
the JEOL 8900 L electron microprobe at the Department of Earth
and Planetary Sciences at McGill University. Samples were mounted
on glass slides using double sided carbon tape and coated with
~ 150 Å of carbon. Samples mapped for starch were stained
with I before carbon coating2, with half of the sample
masked to provide a blank reference (see Figure 3). Experimental
conditions were 15 kV and 20 nA with 3 um pixel spacing. Dwell
times per pixel were 100 ms, and where backgrounds were measured
dwell time per pixel was 50 ms.
Figure 3