The Lower Triassic Werfen Formation of the Karawanken Mountains (Southern Austria) and its disaster survivor microfossils, with emphasis on Postcladella n. gen. (Foraminifera, Miliolata, Cornuspirida)

Abstract

A relatively poorly known sedimentary succession (uppermost Bellerophon Formation and overlying Werfen Formation) including the Permian-Triassic Boundary (PTB) is exposed in the South-Alpine part of the Karawanken Mountains of Southern Austria. As in the Dolomites, sedimentation of the Werfen Formation mainly occurred in a subtidal shelf environment between normal and storm wave base. Muddy sedimentation was periodically interrupted by storm events resulting in the deposition of storm layers. Three sections are accurately studied. All contain the same assemblage of Foraminifera and events from the PTB to the late Early Triassic Meandrospira pusilla zone. Between these two great events, only the cornuspirid foraminiferan Postcladella n. gen. is present. Its populations are described and illustrated here under the name Postcladella kahlori n. comb. In the geological record, many taxa such as P. kahlori, i.e., undivided, tubular, initially planispirally evolute coiled, and later uncoiled, appeared successively. A reappraisal is attempted in order to discriminate the different taxa. These forms are often disaster survivors.