Recent studies show that the distribution of many modern terrestrial species can be explained by a handful amount of large-scale dispersals and that these episodes will likely become more numerous under climatic stress. However, the underlying mechanisms governing these dispersals remain nebulous. Long-distance dispersals across marine barriers, also called sweepstakes dispersals, have always been assumed to be an unpredictable process in which taxa overcome a geographic barrier in a random manner. Yet, there are many instances of dispersals across marine barriers that appear coordinated and non-random. New paleontological findings show that during a short time period marked by extreme surface temperatures, 40 million years ago, Asian anthropoid primates and rodents crossed 500 km of Tethys Sea to reach Africa and 800 km of South Atlantic Ocean to reach South America. This proposal aims to build an empirical and theoretical basis for the origins and mechanisms of sweepstakes dispersal by resolving: how did primates and other mammals disperse across two major seaways 40 million years ago? Are there external forcing mechanisms that make sweepstakes dispersal non-random? This project proposes a combination of paleoclimatic, paleogeographic, and paleontological approaches to evaluate the mechanisms of species dispersal and diversification in deep time, applied to the early dispersal of anthropoid primates. This research will demonstrate how complex geological and climatic phenomena affect the distributions of organisms and the dynamics of invasive fauna, allowing new interpretations about the modern, past and future distribution of species; it will additionally solve one of the biggest mysteries in paleontology, as this episode ranks among the most pivotal events during all of primate evolutionary history.

MioCarb project aims to understand the modern carbon cycle emergence at the late Miocene-early Pliocene (10-4 Ma) transition. This time interval is marked by a global cooling and a steepening of sea surface latitudinal temperature gradient forced by a decrease in atmospheric CO2. Between 9 Ma and 4 Ma, there is an increase in deep oceans carbonate and opal sedimentary fluxes called the Biogenic Bloom which is synchronous with the climatic change. The pelagic carbonate production – an important driver of the carbon cycle – is sustained by the calcareous nannoplankton, photosynthetic algae producing micrometric calcite platelets amount them the coccoliths. During the Biogenic Bloom, there is an increase in the calcareous nannoplankton accumulation rates in the deep oceans. Nevertheless, there are also major macroevolutionary changes within the calcareous nannoplankton community with the decrease in species richness and size and mass per nannofossil. Thel Miocene-early Pliocene carbon cycle transition is then marked by a set of major macroevolutive, biogeochemical and climate changes. MioCarb project aims to understand the origin of the Biogenic Bloom and its impact on the carbon cycle. In order to answer those questions, several complementary tasks are planned: 1) Quantification of calcium carbonate and organic matter mass accumulation rates and calcareous nannofossils and their calcium carbonate mass accumulation rates based on absolute abundance and size quantification over 10 deep-sea drilling sites. This task will quantify CaCO3 by automatic calcimetry and TOC by elementary analysis. The quantification of calcareous nannofossils and their mass will be done with an automatic light microscope purchase with the ANR financial support and the coccolith automatic identification system by artificial intelligence (SYRACO) developed at CEREGE. This task will then quantify the impact of macroevolutionary and paleoceanographic changes on the pelagic sedimentary production during the Biogenic Bloom. 2) Quantification of carbonate mass accumulations at the global scale. This task will focus on data compilation from deep-sea drilling expeditions associated with the state-of-the-art oceanic basins reconstruction from the Australian scientific team EarthByte. This task will lead to a quantitative estimation of CCD evolution through time, the pelagic sedimentary budget and the mass of carbon stored during the Biogenic Bloom. 3) Climatic modeling study including the late Miocene climatic, biologic, sedimentary and geographic specificities in order to reconstruct the origin of the Biogenic Bloom and its impact on the carbon cycle. A team of micropaleontologists, paleoceanographers, sedimentologists, climate modeler, light microscopy engineer and micropaleontology lab technician from CEREGE, AMU and University of Sydney is gathered to carry out this project.

The 14C reservoir age (MRA) for the sea surface is a tracer of air-sea gas exchange and mixing of young carbon derived from the atmosphere with older carbon from subsurface waters. These processes are related to climate, ocean and carbon cycle parameters that varied over the past 50,000 years. The MARCARA project focuses on documenting and modelling the MRA at key locations of the three main oceans. We will generate 14C ages on ultra-small samples by means of the AixMICADAS spectrometer equipped with a versatile solid & gas ion source. This approach will allow us to better quantify MRA and avoid, or correct for, various biases. For numerical modelling, we will use a high-resolution unstructured mesh approach to zoom into the regions of interest and with data assimilation of both marine and atmospheric 14C data. Our data-model integration will be focused on the last deglaciation and abrupt climate changes such as Heinrich stadials and Dansgaard-Oeschger interstadials.

Oceanic plankton are sensitive to physical and biochemical changes in the surface ocean, and are key modulators of the ocean carbon cycle via photosynthesis and calcification. Fossil plankton remains exported to the seafloor and preserved in sediments thus hold key clues on both past climate changes as well as associated biological responses and feedbacks. The western equatorial Indian Ocean (WEIO) is a major player in tropical ocean-atmosphere climate dynamics, with far-reaching impacts on global climate patterns. In 2021, the SCRATCH cruise onboard the research vessel Marion Dufresne II collected high-quality, complete sediment cores spanning the Pleistocene (last ~2 million years) from the WEIO, with the aim of resolving past climate variability and volcanic activity in this important region. Here, we propose to study the co-evolution of plankton, coral reefs, and climate over the Pleistocene. We will perform paired paleogenetic, biomarker, and microfossil analyses, as well as reconstruct key paleoceanographic variables to constrain background climate change, in four sediment cores recovered during SCRATCH. Using state-of-the-art methodologies across three partner institutes, we will combine expertise on paleoceanography, organic geochemistry, genetics, and micropaleontology to address the hypothesis that cyclical changes in the morphology of plankton fossils represent genetic evolution, forced by external climate cycles. Anticipated results will (1) provide a comprehensive picture of paleoceanographic evolution of the WEIO, including Indian Ocean Dipole mean state, (2) demonstrate for the first time the relationship between genetic and morphological plankton evolution in multiple groups, and (3) shed light on external (climatic, volcanic) drivers of evolution, plankton community dynamics, and pelagic versus neritic marine productivity.

Denudation is a key parameter in controlling the dynamics of the Earth’s surface and understanding "how, when, and where" denudation rates respond to climate change is critical. One of the major climate changes that have occurred in the past is the global cooling that took place during the late Neogene. It is characterized by the onset of the Quaternary glaciations and its oscillations and represent one of the most rapid and significant cooling at geological timescales. Synchronously with this cooling, over the last 3-4 Ma, sediment volume exported in marine and continental basin display an apparent 3-fold increase. Because it has been observed in various tectonic settings in both glaciated and non-glaciated regions, one research hypothesis is that this denudation increase is linked to the onset of the high-frequency Quaternary climate cycles, and not to erosion by the glaciers themselves. However, the reality of this Pleistocene denudation enhancement still needs to be confirmed. Methodological bias may explain part of this increase, and the signal linked to the climate oscillations themselves may have been obliterated by tectonics and/or glacier dynamics in some records. Unraveling this signal needs accurate and robust quantification of past denudation rates in regions that were neither glaciated nor tectonically active during the Quaternary. The goal of the PANTERA project is therefore to test this research hypothesis by providing a reliable, detailed and direct record of denudation during the late Neogene, in a region that has been neither covered by ice nor significantly tectonically active during the Quaternary: the western tropical Africa. To achieve these objectives the project will reconstruct past denudation rates during the last 10 Ma, with a Pleistocene focus, from the analyzes of cosmogenic nuclide concentrations (14C, 10Be, 21Ne, 26Al) in present and ancient sediments shed from three main river basins -from North to South, the Ogooue, the SE Congo and the SW Madagascar. We will analyze sediments sampled in offshore cores drilled by SHOM and IFREMER. We will also analyze several continental archives including inland Neogene outcrops, Pleistocene fluvial terraces, cores drilled in Neogene sediments in the center of the Congo basin. As a benchmark, we plan to constrain the recent denudation rates, by analyzing cosmogenic nuclide concentrations (10Be, 21Ne, 26Al) in modern river sand. The goal of the project is to provide denudation rates record at the short time scale (0-900ka) and at the long time scale (0-10Ma) in order to study the impact, on the denudation rates of the Quaternary cycles and the onset of glaciations, respectively. Our project also includes a reconstruction of the rock source and uplift history using U-Pb/U-Th/4He double dating on zircon grains and other geochemical analyses. It will also quantitatively study sedimentary transfer processes via the analyses of muttilpel nuclide together and landscape evolution models incluidng a formulation for clasts transports with calculation of the comsogenic nuclide evolution. The PANTERA project will provide critical results to better understand the impact of the Quaternary glaciations on denudation rates. Its scientific reach goes also beyond and should raise the interest of a large audience either interested in sedimentary processes, tectonics, paleoenvironnemental changes in Africa and anthropogenic impact.