The Schilfsandstein and its flora; arguments for a humid mid-Carnian episode?

E Kustatscher,H.-G Röhling,C Heunisch,S Niegel,M Franz

doi:10.1144/jgs2018-053

Abstract

Recently intensified research on the mid-Carnian episode stimulated discussions about the mid-Carnian climate and a supposed humid climate shift. This basin-scale study on the Schilfsandstein, the type-example of the mid-Carnian episode, applied sedimentological, palynological and palaeobotanical proxies of the palaeoclimate to a large dataset of cored wells and outcrops. The results demonstrate the primary control of circum-Tethyan eustatic cycles on the Central European Basin where transgressions contributed to basin-scale facies shifts. The palaeoclimate proxies point to a uniform arid to semi-arid Carnian climate with low chemical weathering and high evaporation. Consequently, transgressions into the Central European Basin led to increased evaporation forcing the hydrological cycle. The increased runoff from source areas resulted in high-groundwater stages on lowlands characterized by hydromorphic palaeosols and intrazonal vegetation with hygrophytic elements. During lowstands, reduced evaporation and runoff led to increased drainage and desiccation of lowlands characterized by formation of vertisols, calcisols and gypsisols and zonal vegetation with xerophytic elements. The proposed model of sea-level control on the hydrological cycle integrates coeval and subsequent occurrences of wet and dry lowlands, hydromorphic and well-drained palaeosols, and intrazonal and zonal vegetations. Thus, the Schilfsandstein does not provide arguments for a humid mid-Carnian episode. Supplementary material: Datasets of Palynomorph Eco Group (PEG) and Macroplant Eco Group (MEG) analyses are available at https://doi.org/10.6084/m9.figshare.c.4182593

Highlights

The results demonstrate the primary control of circum-Tethyan eustatic cycles on the Central European
The Schilfsandstein represents the type-example of a mid-Carnian episode of increased siliciclastic influx to Tethyan and peri-Tethyan basin and beyond
Simms & Ruffell (1989), Mader (1990) and Fijałkowska-Mader (1999) reconstructed a E pronounced pluvial event, Nitsch (2005) and Kozur & Bachmann (2010) argued for a rather wet phase, T whereas Visscher & Van der Zwan (1981), Reitz (1985), Visscher et al (1994), Kelber (1998), P Heunisch (1999) and Franz et al (2014) rejected significant climate changes. These inconsistencies E may result from the fact that previous studies employed only individual palaeoclimate proxies and/or C were limited to certain areas of the Central European Basin (CEB)

Summary

Introduction

The Schilfsandstein represents the type-example of a mid-Carnian episode of increased siliciclastic influx to Tethyan and peri-Tethyan basin and beyond (see reviews of Arche & Lopez-Gomez 2014; Ogg 2015; Ruffell et al 2015 and references therein). Simms & Ruffell (1989), Mader (1990) and Fijałkowska-Mader (1999) reconstructed a E pronounced pluvial event, Nitsch (2005) and Kozur & Bachmann (2010) argued for a rather wet phase, T whereas Visscher & Van der Zwan (1981), Reitz (1985), Visscher et al (1994), Kelber (1998), P Heunisch (1999) and Franz et al (2014) rejected significant climate changes These inconsistencies E may result from the fact that previous studies employed only individual palaeoclimate proxies and/or C were limited to certain areas of the Central European Basin (CEB). The agglomeration of groups of stems of Equisetites arenaceus of up to 25 cm in diameter give, the impression of a fossil reed bed (Frentzen 1930-31)

Methods

Findings

Discussion

Conclusion