The Valanginian "cold snap" and its impact on terrestrial environments - insights from plant biomarkers, stable isotopes and spore-pollen assemblages

点击翻译按钮获取中文摘要

A critical assessment of terrestrial proxy records is essential to better understand the impact of early Cretaceous climatic variability on continental environments and ecosystems. The proposed project uses land plant biomarkers and spore-pollen records from two different study sites covering the Valanginian carbon isotope excursion (CIE) that allow (1) to address the development of vegetation patterns in response to climatic cooling and associated humidity changes and (2) to access the effects of changes in low- and mid-latitude moisture distribution on plant 13C discrimination. A continuous 150 m section from the Vocontian Basin, SE France will allow to study mid-latitude terrestrial climate evolution and the associated vegetation response at a high time resolution and will be compared in detail with a similar data-set from a low-latitude site (Agadir-Essaouira Basin, Morocco). The establishment of an integrated stratigraphic framework including high-resolution chemostratigraphy will facilitate the integration of the terrestrial records with existing marinederived proxy data on temperature evolution. Based on the δ13C signature of plant-derived biomarkers, a quantitative model of the humidity changes associated with the Valanginian CIE will be established. The achievement of these goals is expected from a combined approach including organic geochemical and palynological investigations as well as biogeochemical modelling.