Luc Beaufort

Luc Beaufort
CNRS & Aix-Marseille Université · CEREGE

PhD

About

335
Publications
41,755
Reads
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8,589
Citations
Citations since 2016
65 Research Items
3601 Citations
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
Additional affiliations
October 1991 - present
French National Centre for Scientific Research
Position
  • Senior Researcher
March 1987 - February 1990
Woods Hole Oceanographic Institution
Position
  • Invited student

Publications

Publications (335)
Article
Full-text available
Although the role of Earth’s orbital variations in driving global climate cycles has long been recognized, their effect on evolution is hitherto unknown. The fossil remains of coccolithophores, a key calcifying phytoplankton group, enable a detailed assessment of the effect of cyclic orbital-scale climate changes on evolution because of their abund...
Article
Heterococcoliths are calcite platelets produced inside diploid coccolithophore cells and extruded to form a covering on the cell surface called a coccosphere. The size of coccoliths is an important parameter sometimes used to identify species, and it is observed to be influenced in extant species by abiotic parameters (e.g., CO2, light). However, t...
Article
Full-text available
Oxygen minimum zones (OMZs) are oceanic areas largely depleted in dissolved oxygen, nowadays considered in expansion in the face of global warming. To investigate the relationship between OMZ expansion and global climate changes during the late Quaternary, quantitative oxygen reconstructions are needed but are still in their early development. Here...
Article
Full-text available
In tropical and sub‐tropical mixed siliciclastic–carbonate depositional systems, fluvial input and in situ neritic carbonate interact over space and time. Despite being the subject of many studies, controls on partitioning of mixed sediments remains controversial. Mixed sedimentary records, from Ashmore Trough shelf edge and slopes (southern Gulf o...
Preprint
Coccoliths are calcite platelets produced inside coccolithophore cells and extruded to form a covering on the cell surface called a coccosphere. The size of coccoliths is an important parameter often used to identify species, and observations on extant species have shown an influence of abiotic parameters (e.g., CO2, light, nutrient concentration)...
Preprint
Full-text available
Oxygen Minimum Zones (OMZs) are oceanic areas largely depleted in dissolved oxygen, nowadays considered in expansion in the face of global warming. Their ecological and economic consequences are being debated. The investigation of past OMZ conditions allows us to better understand biological and physical mechanisms responsible for their variability...
Article
Calcareous nannofossils are micrometric calcite platelets secreted by the photosynthetic algae named coccolithophores and incertae sedis. Calcareous nannoplankton inhabit the photic zone from coast to open-ocean and have left an abundant fossil record since the Triassic. Therefore, they constitute an interesting material for geochemical studies alt...
Article
Full-text available
Identification of microfossils is usually done by expert taxonomists and requires time and a significant amount of systematic knowledge developed over many years. These studies require manual identification of numerous specimens in many samples under a microscope, which is very tedious and time-consuming. Furthermore, identification may differ betw...
Preprint
Full-text available
The effect of global climate cycles driven by Earth’s orbital variations on evolution is poorly understood because of difficulties achieving sufficiently-resolved records of past evolution. The fossil remains of coccolithophores, a key calcifying phytoplankton group, enable an exceptional assessment of the impact of cyclic orbital-scale climate cha...
Article
Full-text available
At present, variations of primary productivity (PP) in the Bay of Bengal (BoB) are driven by salinity-related stratification, which is controlled by the Indian summer monsoon (ISM). The relationships between PP, precipitation, and more generally climate in the past are not clearly understood. Here, we present a new record of PP based on the examina...
Preprint
Full-text available
Identification of microfossils is usually done by expert taxonomists and requires time and a significant amount of systematic knowledge developed over many years. These studies require manual identification of numerous specimens in many samples under a microscope, which is very tedious and time consuming. Furthermore, identification may differ betw...
Preprint
Calcareous nannofossils are micrometric calcite platelets secreted by coccolithophores and incertae sedis photosynthetic algae. Calcareous nannoplankton inhabit the photic zone from coast to open-ocean and have left an abundant fossil record since the Triassic. Therefore, they constitute an interesting material for geochemical studies although it h...
Article
Pollen grains are valuable paleoclimate and paleovegetation proxies which require extensive knowledge of morphotypes and long acquisition time under the microscope. The abundance of damaged, folded, and broken pollen grains in the fossil register and sometimes also in modern soil and sediment samples, has so far prevented automation of pollen ident...
Preprint
Full-text available
Abstract. At present, variations of primary productivity (PP) in the Bay of Bengal (BoB) are responding to salinity-related-stratification which is controlled by the Indian Summer Monsoon (ISM). The relationships between PP, ISM, and to a broader scale, North Atlantic climate rapid variability in the past, are not clearly understood. Here, we prese...
Preprint
Full-text available
Abstract. The coccoliths are major contributors to the particulate inorganic carbon in the ocean that is a key part of the carbon cycle. The coccoliths are few microns in length and weigh few picograms. Their birefringence characteristics in polarized optical microscopy has been used to estimate their mass. This method is rapid and precise because...
Article
Full-text available
Coccoliths are major contributors to the particulate inorganic carbon in the ocean that is a key part of the carbon cycle. The coccoliths are a few micrometres in length and weigh a few picogrammes. Their birefringence characteristics in polarized optical microscopy have been used to estimate their mass. This method is rapid and precise because cam...
Poster
Full-text available
Abstract: The Deep Biomass (DB), located in the lowest part of the euphotic zone (approx. 80 m to 300 m) primarily in the subtropical gyres is an unexplored part of primary production (PP). It is one of the largest biomes on our planet considering that subtropical regions occupy 60% of the total ocean. Recent observations indicate that the major oc...
Article
Coccolithophores are one of the most abundant and widespread groups of calcifying plankton and have attracted extensive study in terms of their likely response to ocean acidification. Conflicting results concerning coccolithophore calcification have been reported from both experimental and field studies. Due to their minute size, it is difficult to...
Conference Paper
Full-text available
The Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) is one of the most severe greenhouse warming events in Earth's history. Thousands of petagrams of carbon were released into the atmosphere-ocean system in only a few thousand years, ultimately causing ocean acidifi cation (Zachos et al., 2005). The gradual sequestration of this light carbon took p...
Article
When micron-sized particles are suspended into the dense brine waters of a deep hypersaline basin, in the absence of biological packaging, their settling velocities should be greatly attenuated. We observed this phenomenon in the anoxic brine water of the Urania Basin in the eastern Mediterranean. We found that the deepest part of this basin is fil...
Poster
Full-text available
Geophysical Research Abstracts Vol. 21, EGU2019-4538-2, 2019 EGU General Assembly 2019 © Author(s) 2019. CC Attribution 4.0 license. We focus on an unexplored part of primary production (PP), the Deep Biomass (DB), located in the lowest part of the euphotic zone (approx. 80 m to 300 m) primarily in the subtropical gyres. The DB is one of the large...
Article
Full-text available
Coccolithophores of the Noëlaerhabdaceae family are covered by imbricated coccoliths, each composed of multiple calcite crystals radially distributed around the periphery of a grid. The factors that determine coccolith size remain obscure. Here, we used synchrotron-based three-dimensional Coherent X-ray Diffraction Imaging to study coccoliths of 7...
Article
Full-text available
Several synergistic mechanisms were likely involved in the last deglacial atmospheric pCO 2 rise. Leading hypotheses invoke a release of deep-ocean carbon through enhanced convec-tion in the Southern Ocean (SO) and concomitant decreased efficiency of the global soft-tissue pump (STP). However, the temporal evolution of both the STP and the carbonat...
Conference Paper
Full-text available
The Eastern Tropical North Pacific (ETNP) is sensitive to climatic changes that either strengthen or weaken the Oxygen Minimum Zone (OMZ). Paleoproxy and model evidence indicate that the shifts from cold stadials (LGM, MIS4) to warm interstadials are often accompanied by sudden sea level rise, intensification of marine productivity and enhanced oce...
Article
Full-text available
The El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) account for a large part of modern climate variability. Over the last decades, understanding of these modes of climate variability has increased but prediction in the context of global warming has proven difficult because of the lack of pertinent and reproducible pale...
Conference Paper
Full-text available
Landsliding processes are relatively well-constrained on clastic sedimentary margins but remain poorly documented along carbonate slope and guyots. The southern central Mozambique Channel, between Mozambique and Madagascar, hosts several isolated carbonate platforms called the “Iles Eparses” and adjacent seamounts, which developed in shallow-water...
Article
Full-text available
We developed a new automated procedure for measuring several pore parameters of benthic foraminiferal calcareous tests. Crushed test fragments are mounted on microscope slides and observed with an optical microscope under natural transmitted light, allowing the observation of pores and fragment outlines. Images are automatically acquired and proces...
Conference Paper
Full-text available
Our ability to track the sensitivity of major Oxygen Minimum Zones (OMZs) to rapid perturbations in climate and productivity can be compromised by (1) global sea level change, (2) insufficient temporal resolution, (3) inadequate age models, and (4) strong microbially mediated transformations and diagenetic overprints. As a consequence, short-term p...
Article
Full-text available
The current-climate Indian monsoon is known to boost biological productivity in the Arabian Sea. This paradigm has been extensively used to reconstruct past monsoon variability from palaeo-proxies indicative of changes in surface productivity. Here, we test this paradigm by simulating changes in marine primary productivity for eight contrasted clim...
Article
The intensity of the Oxygen Minimum Zone (OMZ) of the Eastern North Pacific (ENP) experienced strong variations during the last Glacial, mirroring changes in the balance between export production (O2-consumption) and water mass ventilation (O2-renewal). In this paper we present a new benthic foraminiferal assemblages record from Core MD02-2508, rec...
Article
Full-text available
Coccolithophores are single-celled photosynthesizing marine algae, responsible for half of the calcification in the surface ocean, and exert a strong influence on the distribution of carbon among global reservoirs, and thus Earth’s climate. Calcification in the surface ocean decreases the buffering capacity of seawater for CO2, whilst photosyntheti...
Article
Full-text available
Authigenic 10 Be/ 9 Be ratios from three equatorial ocean cores are stacked and averaged  The 10 Be cosmogenic nuclide overproduction episodes are systematically associated with Geomagnetic Dipole Lows  The 10 Be signatures of the Brunhes/Matuyama transition and Brunhes geomagnetic excursions yield distinct rates and durations Abstract Geomagneti...
Article
Full-text available
Coccolithophores are single-celled photosynthesizing marine algae, responsible for half of the calcification in the surface ocean, and exert a strong influence on the distribution of carbon among global reservoirs, and thus Earth’s climate. Calcification in the surface ocean decreases the buffering capacity of seawater for CO2, whilst photosyntheti...
Article
Full-text available
The Indian monsoon is known to boost biological productivity in the Arabian Sea. This paradigm has been extensively used to reconstruct past monsoon variability from paleo-proxies indicative of changes in surface productivity. Here, we test this paradigm by simulating changes in marine primary productivity for 8 contrasted climates from the last gl...
Poster
Full-text available
Intensity of the Oxygen Minimum Zone of the Eastern North Pacific experienced strong variations during the last Glacial that mirror changes in the balance between export production (O2-consumption) and ventilation (O2-renewal). Here, we present a new record of benthic foraminiferal assemblages from Pacific Core MD022508. That record reflects oxygen...
Article
Full-text available
Calcifying marine phytoplankton—coccolithophores— are some of the most successful yet enigmatic organisms in the ocean and are at risk from global change. To better understand how they will be affected, we need to know “why” coccolithophores calcify. We review coccolithophorid evolutionary history and cell biology as well as insights from recent ex...
Article
Full-text available
Calcifying marine phytoplankton—coccolithophores— are some of the most successful yet enigmatic organisms in the ocean and are at risk from global change. To better understand how they will be affected, we need to know “why” coccolithophores calcify. We review coccolithophorid evolutionary history and cell biology as well as insights from recent ex...
Conference Paper
Full-text available
Oscillations of water column chemistry (especially dissolved oxygen) in coastal marine basins and open seas are controlled by a complex interplay among circulation, climate, productivity, and sea level variability, which can also bear anthropogenic impacts. The underlying marine sediments are capable of recording such changes but often in dissimila...