Sedimentology and carbon isotope stratigraphy of the Rhaetian Hochalm section (Late Triassic, Austria)
Abstract
The Rhaetian (~201-209 Ma, the latest stage of the Triassic) is an important time-interval for the study of environmental changes preceding the End-Triassic Mass extinction. A detailed sedimentological and chemostratigraphic study was conducted in the lower Kössen Formation at Hochalm (Austria), the type-section of the Hochalm Member (Mb). This section exposes mid-Rhaetian sediments deposited in an intraplatform shallow marine basin on the north-western margin of the Tethys. The study highlights eight apparent shallowing-upward sequences from the middle of Unit 2 to Unit 4 of the Hochalm Mb stacked within the long-term transgression that characterizes the Kössen Formation. Both the bulk carbonate and the bulk organic matter δ13C records indicate the presence of a distinct increase in carbon isotope values in the lower part of the lower Hochalm Mb. This excursion might represent a new chemostratigraphic marker that could be used for refining the Rhaetian stratigraphy and represents another important Late Triassic carbon-cycle perturbation prior to the major disturbance associated with the End Triassic biotic crisis.
- Publication:
-
Global and Planetary Change
- Pub Date:
- August 2020
- DOI:
- 10.1016/j.gloplacha.2020.103210
- Bibcode:
- 2020GPC...19103210R
- Keywords:
-
- Rhaetian;
- Sedimentology;
- Carbon isotopes;
- Upper Triassic