Abstract
At the Julian 1-2, a period major break in reef growth took place in the Tethys realm. This lithological change from carbonates to siliciclastics is interpreted to be the result of increased runoff. Increased continental runoff in turn was related to a period of increased rainfall in the adjacent continental areas and is known as Carnian Pluvial Event (CPE). Palynofacies analysis and Rock-Eval pyrolysis was performed on sedimentary organic matter extracted from sediments covering the CPE from the outcrops in Lunz am See in Northern Calcareous Alps (NCA) in Austria. Additionally, C-isotope data from bulk sedimentary organic matter and TOC values were integrated from a previous study. The results are used for the reconstruction of the palaeoenvironmental conditions during the black shale formation, the redox conditions and source rock potential. The negative excursion of δ13Corg of the black shale formation in the Carnian is compared with the Rhaetian, which is another negative excursion of δ13Corg within the western Tethys realm. The sediments were deposited in an epeiric dysoxic-anoxic, neritic shelf with high algae and bacteria productivity. The high productivity was caused by the humid climate during the CPE. Rivers run from Fennoscandinavian hinterland into the NW Tethys margin depositing allochthonous terrestrial matter in the shelf and creating stagnation conditions in the shelf basin. Consequently, the high influx of organic matter and nutrients resulted into eutrophication as algae and bacteria flourish. Furthermore, Rock –Eval pyrolysis reveals kerogen type III and kerogen type IV, but they are generally poor source rock potential due to thickness and maturity and weathering of the organic matter. The CIE is assumed as a good indicator for changes in organic matter.