Global carbon isotopic events in a Campanian-Maastrichtian deltaic succession (Tremp-Graus Basin, Spain) and multiproxy stratigraphy for high sedimentation rate environments

The Campanian to Maastrichtian sedimentary succession of the Tremp-Graus Basin (NE Spain) is char-acterized by the offshore-to-prodeltaic upper Vallcarga Fm giving way to prograding deltaic units (the Aren Fm), which are overlain by transitional facies (the Grey Unit) that correspond to the basal part of the Tremp Group. This work aims to improve the stratigraphical scheme of these deposits using a new dataset of delta C-13 carb and delta(13)Corg, delta O-18 and TOC variations through time, supported by a new bio-stratigraphical analysis and compiling previous biostratigraphical and paleomagnetic data. The com-parison of isotopic signals from marine reference sections where 313Ccarb is well calibrated in the Tethys realm allows recognition of global isotopic events that can be used as correlative marker events. Sig-nificant high-frequency 313C variations defined in the delta C-13 are identified in the studied succession despite the different sedimentary setting and some can be related to global geochemical events such as the Late Campanian Event (LCE) and the Campanian-Maastrichtian Boundary Event (CMBE), in good agreement with the magnetic chrons at the base of the Tremp Group, and with some new biostrati-graphic constraints. From multiple geochemical and petrographic analysis of the organic matter we suggest that the geochemical signal corresponds to global changes, but at higher resolution, sedimentary dynamics are also reflected in the geochemical signals, particularly inputs of surface water in the deltaic signal. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study improves the stratigraphic scheme of the Tremp-Graus Basin sedimentary succession by using a new dataset of isotopic variations and organic carbon content, supported by biostratigraphic analysis and previous data. The research reveals significant isotopic variations in the studied deposits, which can be correlated with global geologic events.