PRELIMINARY STABLE ISOTOPE ANALYSES OF PERMIAN-TRIASSIC PEDOGENIC CARBONATE NODULES FROM THE SOUTHERN URALS, RUSSIA

The Permian/Triassic (P/Tr) boundary is widely assumed to have been a time of extreme environmental upheaval and change. A possible record of this is a notable negative anomaly in both stable δ¹³C and δ¹⁸O isotope records at or near the P/Tr boundary recorded in multiple marine and terrestrial sections round the globe. In the terrestrial realm, this anomaly has been reported from the Transantarctic Mountains in Antarctica, the Karoo Basin in South Africa, Australia, India and Madagascar which has been linked to several extinction mechanisms including the Siberian Traps and mass methane release. However these sections are all from southern palaeolatitudes.

Herein we describe the first analysis of sections from northern palaeolatitudes. The Permian - Triassic terrestrial sedimentary record of the South Urals, in Russia, contains many vertisol palaeosol horizons. These horizons include pedogenic carbonates at different stages of development, both above and below the P/Tr boundary. Preliminary analyses of the δ¹³C_carb and δ¹⁸O_carb signatures of these pedogenic carbonates have revealed a number of negative excursions in δ¹³C_carb and δ¹⁸O_carb in the Late Permian, including a negative excursion that begins in the latest Permian and continues into the Early Triassic. This data is being used to shed new light on the size and timing of the negative excursions in the northern palaeolatitudes.