Molecular indicators for coal-forming vegetation of the Miocene Chukurovo lignite, Bulgaria

Molecular indicators for angiosperm vegetation are also recognized in the bulk coal. The presence of olean-12-ene, urs-12-ene, 24,25-dinoroleana-1,3,5(10)12-tetraene, and 24,25-dinorursa-1,3,5(10)12-tetraene all indicate flowering trees and provide the possibility to further assess the paleoplant community. The triterpenoid data indicate oxic diagenetic transformation of plant detritus had proceeded by aromatization of ring A-E.