DEVELOPMENT OF LATE TRIASSIC PALEOENVIRONMENT IN THE NORTHEASTERN PARIS BASIN UNDER SPECIAL CONSIDERATION OF THE END-TRIASSIC MASS-EXTINCTION EVENT (ETE)

The Environmental Geology Group at Bonn University is working on the Upper Triassic and Lower Jurassic sediment series in the Trier Luxembourg Embayment. The aim is to the reconstruct the paleoenvironmental changes in a period of the earths history, in which the Paris Basin starts to form and Pangea is breaking up, generating the Middle Atlantic Ocean with a high tectonic activity and the eruption of a large igneous province (CAMP).

The working area is affected by another catastrophic event: the impact of a large asteroid in the NW Massif Central. Both events have been recognized in the End-Triassic sediments of the research area.

The Rhaetian is subdivided into a lower sandstone-siltstone sequence (Sables de Mortinsart) and a upper part built up by a characteristic reddish brown claystone (Marnes de Levallois). This is overlain by dark grey marls with fossiliferous limestones of the lowest Hettangian.

Intercalated between the Sables de Mortinsart and the Marnes de Levallois is a conglomerate, eroding a slumped silt-clay-horizon with water escape structures. It is grading upwards into a disturbed sequence of gravel-silt-clay, overlain by microslumped Argiles de Levallois.

The authors interprete it as a tsunamite, triggered by the Rochechouart impact (Kuhlmann & Thein 2014). Several microslumped horizons can be observed in the Argiles de Levallois, which might be the result of earthquakes generated by the initial tectonic events of CAMP (Lindström et al. submitted)

Geochemical analyses allow to trace the development of the shallow marin sedimentary environment through the Rhaetian in terms of salinity, oxgen content and climate. δ ¹³C_org - and palynological data give a good correlation to other sections in Europe and beyond this.

References

Kuhlmann, N., Thein, J., (2014): Sediment deformation horizons in the Upper Triassic (Rhaetian) of the northeastern Paris Basin: generated by syngenetic tectonic movements and /or a large asteroid impact. Frankfurt, Germany.

Lindström, S., Pedersen, G. K., van de Schootbrugge, B., Hansen, H. K., Kuhlmann, N., Thein, J., Johansson, L., Petersen, I. H., Alwmark, C., Dybkjaer, K., Weibel, R., Erlström, M., Nielsen, H., L., Oschmann, W., Tegner, C. (submitted): Intense seismicity due to end-Triassic emplacement of a large igneous province.

This work has been supported by FNR Luxembourg