AROMATIZED ARBORANE FERNANE HYDROCARBONS AS MOLECULAR INDICATORS OF FLORAL CHANGES IN UPPER CARBONIFEROUS LOWER PERMIAN STRATA OF THE SAAR-NAHE BASIN, SOUTHWESTERN GERMANY/
M. Vliex et al., AROMATIZED ARBORANE FERNANE HYDROCARBONS AS MOLECULAR INDICATORS OF FLORAL CHANGES IN UPPER CARBONIFEROUS LOWER PERMIAN STRATA OF THE SAAR-NAHE BASIN, SOUTHWESTERN GERMANY/, Geochimica et cosmochimica acta, 58(21), 1994, pp. 4689-4702
Thirty-seven coal samples of Upper Carboniferous and Lower Permian age
from three boreholes in the Saar-Nahe Basin, Germany, have been studi
ed by organic geochemical and coal petrological methods. The investiga
tions were aimed at the recognition of floral changes in the Upper Car
boniferous and Lower Permian strata. The results show that composition
al changes in the extracts are only partly caused by variations in coa
lification. Specific aromatic hydrocarbons appear in Upper Westphalian
D coal seams and increase in concentration up to the Rotliegendes. Th
e dominant compound has been identified by mass spectrometry and NMR-s
pectroscopy as 5-methyl-1 thylpentyl)-des-A-25-norarbora(ferna)-5,7,9-
triene (MATH) and always occurs associated with 25-norarbora(ferna)-5,
7,9-triene. Both compounds are thought to originate from isoarborinol,
fernene-3 beta-ol, or fernenes. The strongly acidic conditions during
deposition of the coals might have induced the 4,5-cleavage combined
with a methyl-shift in an arborane/fernane-type pentacyclic precursor
yielding the MATH. Based on petrological investigations, palynomorphs
related to early Gymnospermopsida such as Pte- ridospermales and Conif
erophytes (Cordaitales and Coniferales) increased in abundance in the
strata beginning with the Upper Westphalian D concomitant with the abo
ve mentioned biomarkers. The results suggest the arborane/fernane deri
vatives originate from the plant communities producing these palynomor
phs.