Image description: I enjoy the sedimentology and stratigraphy of the lacustrine records we work on. This is a photo describing sediments from Schliersee Lake, located in southern Germany.
Rodrigo Martínez-Abarca
Germany
February 10, 2026
Climate and environmental variability in the eastern equatorial Atlantic and the northern tropical Americas: from orbital cycles to human activity
This talk explores climate and environmental variability in the eastern equatorial Atlantic and northern Neotropics during the Late Quaternary. Marine sediments from ODP Site 663, analyzed with X-Ray Fluorescence geochemistry, reveal orbital- and half-precessional-scale dynamics of the West African Monsoon over the last 1.25 million years. In contrast, lipid biomarkers and elemental data from Lake Petén Itzá sediments document hydroclimate variability during the past 400 thousand years, shaped by hemispheric-scale changes and human activity in Central America. Together, these records highlight the sensitivity of tropical systems to external and internal forcing and their relevance for understanding past and future climate change in densely populated regions.
Image description: Picture of Jonathan a white man wearing a cap, field shirt and smiling with a backdrop of Colorado plateau at Bluff, Utah, USA.
Jonathan Stine
USA
February 17, 2026
Paleozoic Equatorial Records of Melting Ice Ages (PERMIA): calibrating the pace of paleotropical environmental and ecological change during the Late Paleozoic Ice Age
The upper Paleozoic Cutler Group of southern Utah, USA, is a key sedimentary archive for understanding the Earth-life effects of the planet’s last pre-Quaternary icehouse–hothouse state change: the Carboniferous–Permian (C–P) transition (~304-290 Ma). Within the near-paleoequatorial Cutler Group, this transition corresponds to a large-scale aridification trend, loss of aquatic habitats, and ecological shifts toward more terrestrial biota as recorded by its fossil assemblages. However, fundamental questions persist. (1) Did continental drift or shorter-term changes in glacio-eustasy, potentially driven by orbital (Milankovitch) cycles, influence environmental change at near-equatorial latitudes during the C–P climatic transition? (2) What influence did the C–P climatic transition have on the evolution of terrestrial ecosystems and on the diversity and trophic structures of terrestrial vertebrate communities?
The Paleozoic Equatorial Records of Melting Ice Ages (PERMIA) project seeks to resolve these issues by studying the Elk Ridge no. 1 (ER-1) core. This legacy core, collected in 1981 within what is now Bears Ears National Monument, recovered a significant portion of the Hermosa Group and the overlying lower Cutler Group, making it an ideal archive for studying paleoenvironmental change during the C–P transition. Using a combination of biostratigraphy, geophysical and geochemical core scans, cyclostratigraphy, and magnetostratigraphy, we tentatively determine that the aridification event, and associated biotic turnover, occured on a timescale more indicative of climate change rather than tectonic movement.
Pal(a)eoPERCS 