Quantitative palaeobathymetric reconstructions based on foraminiferal proxies: a case study from the Neogene of south‐west Spain

Abstract

Quantitative palaeobathymetric reconstructions based on foraminiferal proxies have been used in a wide variety of geological studies on tectonic, climatic and environmental changes in sedimentary basins. However, palaeo‐water‐depth estimates are frequently biased due to taphonomic processes (dissolution, transport) as well as local conditions (primary productivity, oxygen content, and organic matter fluxes). This study evaluated the level of reliability of three commonly used transfer equations based on planktic and benthic foraminiferal proxies that produce different palaeobathymetric results, using Neogene sediments from the Guadalquivir Basin, south‐west Spain. The most trustworthy method involves removing abundant infaunal benthic foraminifera before applying the palaeo‐water‐depth equation based on benthic foraminiferal water‐depth ranges and presence/absence of species. This new approach provides sound palaeobathymetric results that improve estimations of long and short‐term relative sea‐level changes with negligible influence of taphonomic as well as ecological factors. When using one equation based on planktic/benthic ratios (P/B ratios), removing all infaunal benthic foraminiferal species improves the accuracy of P/B ratios, which yields more accurate palaeodepth reconstructions despite the low level of trustworthiness of this equation for both long and short‐term relative sea‐level variations.

Geomorphological and morpho-sedimentary features of a sand barrier in a tectonically asymmetrical estuary during the Late Holocene: La Algaida (SW Spain)

“…3) had higher energy and received higher inputs of marine sediment than more sheltered areas (core A2 site). This is indicated by evidence including: (1) a lower P/B ratio, suggesting that less-resistant, delicate planktic foraminiferal shells were preferentially destroyed (Kucera, 2007;Pérez-Asensio et al, 2017;Pérez-Asensio, 2021); (2) lower N/g (i. e., more sediment supply); and (3) more abundant marine fauna in core A1 than in core A2 (Fig. 3).…”

Geology and stratigraphy of the Neogene section along the Oued Beth between Dar bel Hamri and El Kansera (Rharb Basin, northwestern Morocco) and its otolith-based fish fauna: a faunal inventory for the Early Pliocene remigration into the Mediterranean

“…During the Pliocene, the Rharb Basin was a funnelshaped embayment that represented the relict of the last connection of the Atlantic with the Mediterranean (Fig. 29) (Achalhi et al, 2016;Capella et al, 2017;de Weger et al, 2020ade Weger et al, , 2020bde Weger et al, , 2020cFlecker et al, 2015;Flinch, 1993;Martin et al, 2014;Pérez-Asensio, 2021). The Rharb Basin is ideally situated to investigate the composition of the fauna during the late stage of the Atlantic-Mediterranean connection and the fauna during the re-flooding when the Rharb Basin represented the reservoir from which a proportion of the remigration must have been recruited.…”

Climate and Atlantic sea-level recorded in Southwestern Spain from 6.3 to 5.2 Ma. Inferences on the Messinian Crisis in the Mediterranean.

“…Fortunately, the interpretation of the Montemayor-1 borehole in terms of changes in sea level in correlation with the Messinian Crisis in the Mediterranean (Jiménez-Moreno et al, 2013;Pérez-Asensio et al, 2013;Pérez-Asensio, 2021) highlights the importance of the data acquired from the Carmona boreholes and outcrops and their revaluation.…”