Inorganic isotopes of the lower Pliensbachian Santiurde section (Basque-Cantabrian basin, northern Spain)

Resumo

We present inorganic C and O stable isotopes from the lowermost Pliensbachian organic-rich hemipelagic Santiurde section (Basque-Cantabrian basin, north Iberian palaeomargin, Spain). The Santiurde section studied herein is exposed at exit 144 of motorway A67 (UTM X411431.091 Y4769002.593), approximately 50 km south-west of Santander city. The expanded hemiplegic succession offered a potentially valuable orbitally paced stratigraphic record. An integrated multiproxy study was performed in the 19 beds found between 12.4 and 15.95 m of the lower Pliensbachian succession in order to disentangle what sedimentary processes and environmental factors influenced the formation of the hemipelagic rhytmites. Sampling was mainly carried out in 2019. Fifty-seven samples were collected in order to analyse their %CaCO3 and inorganic d13Ccarb and d18Ocarb content. Inorganic isotopes were analysed at the Leibniz Laboratory for Radiometric Dating and Stable Isotope Research (Kiel University, Germany) using a Kiel IV carbonate preparation device connected to a ThermoScientific MAT 253 mass spectrometer.