Title: Two contrasting resin chemistry from Rajasthan basin and their significance

Abstract

Resin samples from two mines namely, Barsingsar and Jalipa Mine from Bikaner-Nagaur Basin and Barmer Basin respectively, belonging to Paleogene lignite sequences of Rajasthan, western India were analysed for understanding their chemistry in light of their floral aspects. The terpenoid composition gives us characteristic and contrasting signature to understand the predecessors. The presence of high amount of sesquiterpenoids in both the mines hint to a non specific high land plant input. The sesquiterpenoid class compounds for Barsingsar samples include drimane, 8- Isopropyl-2,5-dimethyl-2,5- dimethyl-1,2,3,4 -tetrahydro naphthalene, cadalenes, norcadalenes, chamuzulene etc. The high abundance of diterpenoids like various unidentified abietane class compounds, 16,17,18- Bisnordehydroabietene, 14-Methyl-16,17-bisnordehydroabietane, podocarp-8,11,13-teiene-12-ol, Rosane, etc point to a conifer source where Podocarpacae is a probable source for the resin from Barsingsar. The major compounds identified in the Jalipa fossil Resin were 2,6-dimethyl-1,2,3,4-tetrahydro-naphthalene, α-muorolene, dihydrocurcumene, calamenene, 5,6,7,8-tetrahydrocadalene, cadalene and C30 cadinene dimers. The compounds identified for Jalipa Resins in the first group are C15 bicyclic sesquiterpenoids and the second group consists of their dimer products. The second group of compounds had a mass spectra corresponding to bicadinene products which are chemotaxonomic markers for angiosperm family Dipterocarpacae. The presence of two distinct genus markers in relative lignite sequences indicate the diversity palaeogene of India. The research provide a good scope to understand how various resin producing floral elements played their significant part in the tropical forests in South East Asia with the help of resin chemisty.