Plant biomarkers and elemental compositions reveal transport changes on the Iberian margin across the late Neogene
Year: 2026
Type: preprint
Abstract: To reconstruct Iberian Margin paleoclimate and the effects of Mediterranean gateway restriction during the late Miocene, International Ocean Discovery Program Expedition 401 drilled Site U1609 on the southwestern Portuguese Margin (37º22.6259’N, 9º35.9120’W; 1660 m water depth) in the path of Mediterranean Overflow Water (MOW). We present a multiproxy study of plant waxes, lignin phenols, palynomorphs, and X-ray fluorescence. From 11.5–9.5 Ma, hemipelagic sediments have high Ca and dinoflagellate:pollen ratios. Between 9.5 and 6 Ma plant proxies (e.g., alkanes and lignin) and terrigenous elements (e.g., Ti) become more abundant, with more land-based flux attributed to tectonic uplift and the initiation of MOW. Sediments from 6–2.5 Ma indicate relatively stable elemental proportions, although precessional pacing of Ti/Ca occurs throughout the record. Plant wax n -alkane δ 13 C and δD values indicate C 3 vegetation and Atlantic storm tracks, like modern, occurred throughout the warmer Tortonian–Zanclean climates. In contrast, lignin indicates greater variability across the record. High lignin transport and low syringyl/vanillyl ratio suggest riverine export from high-elevation conifer forests in the SE Iberian Peninsula, followed by lateral ocean current transport transport, with fluxes increasing as MOW strengthened at 4.5 Ma. During the Messinian Salinity Crisis, when MOW ceased, lignin delivery was reduced and restricted to lowland riverine inputs from SW Iberia, where angiosperms today dominate the exported woody biomass. We find river-exported gymnosperm lignin to be a valuable tracer of distal advection tracking the history of MOW across the Messinian gateway reorganization.
Authors: Yunlang Zhang, Sophie Warny, Gonzalo Jiménez-Moreno, Xiaojuan Feng, Zongguang Liu, Trevor J. Williams, Francisco J. Rodríguez-Tovar, Manuel Teixeira, Francisco Javier Hernández Molina, Simon C George, Melissa A. Berke, Fadl Raad, Francisco Javier Sierro, Rachel Flecker, Emmanuelle Ducassou, Sarah J Feakins
Institutions: University of Southern California, Louisiana State University, Universidad de Granada, Chinese Academy of Sciences, Institute of Botany, University of South Florida St. Petersburg, Instituto Andaluz de Ciencias de la Tierra, Macquarie University, University of Notre Dame, Université de Montpellier, Géosciences Montpellier, Universidad de Salamanca, University of Bristol, Université de Bordeaux
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225062912