Palaeoenvironmental changes across the Mid- and latest Maastrichtian events: Planktic foraminiferal inference from the Elles section (central Tunisia)

Based on quantitative changes in the Maastrichtian planktic foraminiferal species distribution patterns from the Elles section (central Tunisia), & delta;13C, & delta;18O-based palaeotemperature and inferred proxies (species diversity, ecological associations, and depth ranking), the palaeoenvironment is inferred. Based on Constrained Clustering and corroborated by Non-metric Multidimensional Scaling (NMDS), four statistically significant intervals are identified. Interval 1 (lower-middle part of CF5 Zone) is marked by a warm, oligotrophic, stable, and well-stratified upper water column. Interval 2 (upper part of CF5 Zone), here designated as the pre-Mid-Maastrichtian Event (MME) event, is marked by stressed, warmer, moderately mesotrophic, and weakly stratified surface waters with an unstable upper water column. Interval 3 (CF4 Zone) encompasses the MME and is marked by warm, stable, mesotrophic surface waters with a moderately well-stratified upper water column. The upper part of Interval 3, designated as post-MME, is also marked by mesotrophic conditions, but with increased surface water warming, unstable and stressed conditions. Interval 4 (CF3-CF1 zones) shows the effects of the Indian Deccan volcanism, and is marked by warmer surface waters, mesotrophic, unstable, stressed environmental conditions, with a weakly-stratified upper water column. Maastrichtian palaeoenvironmental analyses from the Elles section (central Tunisia) was carried outPlanktic foraminifera species distribution, diversity proxies, & delta;13C and & delta;18O-based palaeotemperatures were used.Four statistically significant intervals are notedInterval 1 reflects stable, warm, oligotrophic and a well stratified upper water column.Interval 2, pre-Mid-Maastrichtian Event (MME), is marked by unstable, warmer, oligotrophic and a weakly-stratified upper water column.Interval 3, MME, is marked by cool, stable, mesotrophic and moderately well-stratified upper water column.Interval 4 is marked by warm, mesotrophic, unstable, weakly-stratified and stressed conditions.image

Automated summary

Based on quantitative analysis of planktic foraminiferal species distribution and paleotemperature in the Late Cretaceous Elles section in central Tunisia, the paleoenvironmental changes are inferred. Four statistically significant intervals are identified, each characterized by different temperature, nutrient level, and water column stratification.