Discriminating between tectonic and eustatic controls on the stratigraphic record in the Paris basin

Abstract

The quantification of tectonic and eustatic factors in the control of the sedimentary record is one of the main questions in sedimentary basin dynamics. We propose two methods allowing: (i) 3D measurement of accommodation at basin scale and (ii) to decipher between local (10-100 km wavelength) and basin-scale accommodation. The local signal is necessarily of tectonic origin, the basin-scale signal is of both eustatic and large tectonic origin. The measurement of accommodation requires (a) high-resolution time-lines calibrated in ages (sequence stratigraphy on well-logs and biostratigraphy on cores), (b) decompacted lithologies (well-logs), and (c) palaeodepth/palaeoaltitude (sedimentology and well-logs). Application of these methods to the intracratonic Paris basin during the Lias (early Jurassic) suggests a tectonic origin for the 1-5 Myr stratigraphic cycles, with basin-scale flexure during transgressive half-cycles, and 10-100 km uplift of basement units, during regressive half-cycles.