Stable Isotope Event Markers Near the Permo-Triassic Boundary in the Karavanke Mountains (Slovenia)

Abstract

Permo-Triassic (P/Tr) boundary events, which took place approximately 250 Ma ago, led to the most extensive mass extinction in the history of life. A number of possible explanations for this profound break in the evolution of life have been proposed, such as volcanic activity, sea-level fluctuation, changes in sea-water chemistry, an extra-terrestrial impact event and various related factors (YOICHI, 1994). The most recently proposed cause of the mass extinction at the end of the Permian is a combination of these more or less co-occurring events operating in three phases (ERVIN, 1996). The first began with the marine regression during the Late Permian and resulted in the destruction of many marine basins, reduction in the habitat area of many organisms and increased climatic instability. The second phase involved the eruption of the Siberian Traps and further environmental degradation. The final phase may have started immediately prior to the boundary when the Late Permian regression ended and the earliest Triassic transgression begun. The global events outlined above coincide with isotope and elemental anomalies recorded in several P/ Tr boundary sections all