M. Strachan, R. Alexander, R. Kagi
May 1, 1988
Citations
10
Influential Citations
212
Citations
Quality indicators
Journal
Geochimica et Cosmochimica Acta
Abstract
Abstract Three sedimentary sequences and a number of crude oils have been analysed for trimethylnaphthalenes (TMNs) using gas chromatography. The sediments were found to contain enhanced relative abundances of 1,2,5-TMN and 1,2,7-TMN in samples of Cretaceous age and younger; this was especially pronounced in lower maturity sediments containing type III organic matter. Older samples containing type III organic matter were found to contain enhanced relative abundances of 1,2,5-TMN and lower relative abundances of 1,2,7-TMN. 1,2,7-TMN appears to be derived directly from the structural degradation of oleanane-type triterpenoids present in angiosperms, and as such is proposed as a marker for this class of plant and indirectly, therefore, also for samples deposited since the Early Cretaceous. The crude oils have been classified according to their trimethylnaphthalene compositions. This classification enables crudes of higher plant origin to be identified and to be further classified according to whether the organic matter pre-dated or post-dated the evolution of angiosperms.