Oceanic transport of fossil dammar resin: The chemistry of coastal resinites from South Australia

Fragments of resin and fossilised resin (resinites) occasionally wash ashore along the southern Australian coast. Chemical and isotopic analyses were carried out on a suite of coastal and reference resinites to determine the likelihood of a local, as opposed to a distant, origin. All of the coastal resinites were found to contain a polymer based on the sesquiterpenoid cadinene skeleton and were markedly different to the diterpenoid resinites found in local Victorian coals. The coastal resinites closely resemble both fossil and recent dammar resin—a material associated primarily with the tropical angiosperm hardwoods of Southeast Asia, and one which has no known Australian source. Minor variations in the composition of our resinite samples are attributed to differences in their thermal history. These findings confirm the viability of long-distance oceanic transport, not only for the resinites but also for the waxy bitumens that strand along the same coastline. Analytical data on the coastal resinites also help to clarify the role of dammar resin in generating bicadinanes—a class of source and age-specific triterpanes found commonly in the Cainozoic oils and sediments of Southeast Asia.