Stable hydrogen isotopic composition of biomarkers in torbanites from different palaeogeographical locations

The stable hydrogen isotopic composition of selected biomarkers in torbanites from Scotland and Australia, (Late Carboniferous to the Late Permian), deposited under various climate regimes (glacial, cool-temperate and tropical), are under investigation. The ðD of n-alkanes in the extracts from Eastern Australian (Temi) torbanites (Early Permian) deposited under glacial conditions are significantly depleted in D relative to n-alkanes in a torbanite from Scotland (Torbane Hill), deposited during the Carboniferous under a tropical climate regime. Two other Eastern Australian (Newnes) torbanites, deposited during Late Permian times under cool-temperate conditions, contain n-alkanes with ðD values falling in between those of n-alkanes in tropical and glacial sediments. The ðD data acquired for n-alkanes are in accordance with the typical ðD of meteoric waters. A saw-toothed profile of ðD values obtained for the n-alkanes in the Australian torbanites is attributed to a dual-source system, perhaps a predominant Botryococcus braunii input, with a second minor contribution from land plants.

Plot indicating differences in ðD composition of n-alkanes in torbanites from different palaeogeographical locations

Personnel

K. Grice, R. Alexander, D. Dawson

Funding

ARC (QEII)