25th International Meeting on Organic Geochemistry IMOG 2011

P-271
Terrestrial-derived biomarkers from Carboniferous coal deposits
at Dunbar (East Lothian, Scotland): Palaeobotanical and
palaeoenvironmental significance
Maria-Fernanda Romero-Sarmiento 1,2 , Armelle Riboulleau 2 , Marco Vecoli 2 , Fatima
Laggoun-Défarge 4 , Gerard J.-M. Versteegh 3
1 IFP Energies Nouvelles, Rueil-Malmaison cedex, France, 2 Université Lille 1 & CNRS FRE 3298, Villeneuve
d'Ascq cedex, France, 3 MARUM Universität Bremen, Bremen, Germany, 4 Université d'Orléans-INSU-
CNRS (corresponding author:maria-fernanda.romero-sarmiento@ifpen.fr)
Carboniferous (Viséan) coals from Dunbar, East
Lothian – Scotland contain well-preserved miospore
and megaspore assemblages suggesting a lycopoddominated
forest ecosystem with some ferns,
sphenopsids and pteridosperms [1-2].
The thermal immaturity of the organic matter and
the well defined microflora permit to assess the
palaeoenvironmental significance of lipid biomarkers
extracted from these coals. Rock-Eval and lipid
analyses indicate a fully terrestrial depositional
environment. Although a wide diversity of other lipid
biomarkers (alkanes, hopanoids, steroids) was
detected, we focus on the terrestrial-derived
biomarkers.
Combustion-derived PAHs pyrene, fluoranthene,
benzo[a]anthracene (Fig. 1) indicate the occurrence
of forest fires in the study areas during Early
Carboniferous times. Ionene and alkyldibenzofurans
derive from sporopollenins and lichen-biomass
respectively. Retene, cadalene, simonellite,
tetrahydroretene and kaurane are poorly specific and
can derive from a variety of early Palaeozoic land
plants.
Fig. 1. Total ion current (TIC) for selected sample.
Abietane, phyllocladane, ent-beyerane (Fig. 2) and
4β(H)-eudesmane as well as bisnorsimonellite,
diaromatic totarane, diaromatic sempervirane and 2methylretene,
however, as yet had only been reported
from conifers, which do not appear in the fossil record
until the Late Carboniferous [3]. Within the lower
Carboniferous forest ecosystem documented by the
spore content of these coals, arborescent lycopsids
are proposed as alternative sources for these
compounds.
Fig. 2. Partial m/z 109+123+193+233 fragmentogram
for selected sample.
References
[1] Spinner, E. Palaeontology 12
[2] Spinner, E., Clayton, G. Pollen & Spores XV.
[3] Scott, A. Nature 251.
404