Simulated diagenesis of plant cuticles - implications for organic fossilisation

The possible origin of the characteristic compositions of pyrolysates of or ganic fossil leaf cuticles has been investigated by heat treatment of cutic les of recent Kalanchoe glandiflora followed by flash pyrolysis-gas chromat ography. Dewaxed cuticles, whether heat-treated or not, yield mainly cyclic compounds from adventitious cell-wall material together with cutin monomer s. The pyrolysate of waxy cuticle includes the same compounds but is domina ted by wax components which are simply desorbed unchanged under the conditi ons of pyrolysis. However prior heat treatment of waxy cuticle transforms t he pyrolysate so that its chromatogram shows a prominent series of alkene-a lkane peaks from C-8 to C-34, typical of fossil leaf cuticles. It is conclu ded that leaf waxes, instead of or in addition to cutan, are a principal so urce of the aliphatic constituents of organic fossil leaf cuticles. (C) 200 1 Elsevier Science B.V. All rights reserved.