Claude Hillaire-Marcel | Université du Québec à Montréal (original) (raw)

Papers by Claude Hillaire-Marcel

Journal of Foraminiferal Research

Microfaunal assemblages of benthic foraminifera, ostracods, and tintinnids from two marine sedime... more Microfaunal assemblages of benthic foraminifera, ostracods, and tintinnids from two marine sediment cores retrieved from the Herschel Basin of the Canadian Beaufort Sea shelf document relationships with environmental parameters such as salinity, sea-ice cover, and turbulence. Cores YC18-HB-GC01 and PG2303-1 were collected at 18 and 32 m water depth, respectively. At these sites, sediment accumulation rates range between 0.6 and 1.7 cm yr–1 allowing a near-annual temporal resolution over the last 50 years. Multivariate analyses indicate that benthic foraminiferal assemblages respond primarily to food supply. Dissimilarities between the microfaunal assemblages of the two cores are mainly the result of bottom water salinity levels linked to water depth. High abundance of the benthic foraminiferal species Elphidium clavatum and occurrences of Elphidium bartletti point to varying, but relatively low, salinities at the shallow core site YC18-HB-GC01, which may be affected by variations in...

arXiv (Cornell University), Feb 3, 2021

The sea-ice cover of the Arctic Ocean is an important element of the climate and ocean system in ... more The sea-ice cover of the Arctic Ocean is an important element of the climate and ocean system in the Northern Hemisphere as it impacts albedo, atmospheric pressure regimes, CO2-exchange at the ocean/atmosphere interface as well as the North Atlantic freshwater budget and thermohaline circulation [1]. Due to global warming, the Arctic sea-ice cover is presently evolving at an unprecedented rate towards full melt during the summer season, driving the so-called "Arctic amplification" [2]. However, the Arctic sea-ice has also experienced large amplitude variations, from seasonal to orbital (Milankovitch) time scales, in the past. Recent studies led to suggest that whereas insolation has been a major driver of Arctic sea-ice variability through time, sea-level changes governed the development of "sea-ice factories" over shelves (Figure 1), thus fine-tuning the response of the Arctic Ocean to glacial/interglacial oscillations that is slightly out of phase compared to lower latitudes [3,4]. We discuss below how insolation and sea-level changes may have interacted and controlled the sea-ice cover of the Arctic Ocean during warm past intervals and how they could still interfere in the future. The "Milankovitch" pacing of the Arctic Ocean climate and sea-ice The insolation of the Summer solstice at 65°N is commonly used as a timer for ice growth and decay in the Northern Hemisphere [5]. However, because the Arctic sea-ice records its minimum extent in September [6], the heat accumulated and transferred from lower latitudes over the whole summer season may be more relevant. Through time, the pacing of summer vs solstice precessional maxima are close (Figure 2a), but their relative amplitude differs significantly from one peak to another. Moreover, the two curves depict a timing offset of a few thousand of years (Figure 2b). Prior to looking deeper into these features, the choice of the 65°N latitude (~ Iceland) for estimating a "Summer" insolation forcing of the Arctic Ocean sea-ice cover deserves examination. On one hand, the pattern is not significantly different with Summer insolation at 80°N. It would be slightly lower (-22.7±2.7 W.m-2 ; ± 1) but nearly parallel. On the other hand, an important vector of heat towards the Arctic Ocean is the North Atlantic Water (NAW) mass (Figure 1), which flows

Introduction: Paleoceanography, tracers, proxies and methods (C. Hillaire-Marcel, A. de Vernal). ... more Introduction: Paleoceanography, tracers, proxies and methods (C. Hillaire-Marcel, A. de Vernal). Part 1 : Deep Sea Sediment Properties. 1. Deep-sea sediment deposits and properties controlled by currents (I.N. McCave). 2. Continuous physical properties of cored marine sediments (G. St.Onge et al). 3. Magnetic stratigraphy in paleoceanography: reversals, excursions, paleointensity and secular variation (J. Stoner, G. St. Onge). 4. Clay minerals, deep circulation and climate (N. Fagel). 5. Radiocarbon dating of deep-sea sediments (K.A. Hughen). Part 2: Biological tracers and biomarkers. 6. Planktonic foraminifera as tracers of past oceanic environments (M. Kucera). 7. Paleoceanographical proxies based on deep-sea benthic foraminiferal assemblage characteristics (F. Jorissen, C. Fontanier, R. Thomas). 8. Diatoms: From Micropaleontology to Isotope Geochemistry (X. Crosta, N. Koc). 9. Organic-walled Dinoflagellate Cysts: Tracers of sea-surface conditions (A. de Vernal, F. Marret). 10. Co...

Goldschmidt2021 abstracts, 2021

Geochemistry, Geophysics, Geosystems, 2018

We provide a high‐resolution and complete paleomagnetic study from a middle‐Holocene (~4,100–3,30... more We provide a high‐resolution and complete paleomagnetic study from a middle‐Holocene (~4,100–3,300 years Before Common Era, BCE) dome‐shaped speleothem (SPAIV) from Algarve, Portugal. Our results show that the SPAIV speleothem carries a primary and stable remanent magnetization, for which directions are similar to other speleothems from the western Alps. Magnetic declination and inclination curves are also comparable to current paleosecular variation models (SHA.DIF.14k, CALS10k.1b, and pfm9k.1a), one of them (SHA.DIF.14k) fitting better with the present data set. Relative paleointensity was estimated using two different methods: conventional normalization of natural remanent magnetization by anhysteretic and isothermal, and the pseudo‐Thellier method, which is being tested here for the first time in a speleothem. Both methods show similar results, with a minimum intensity peak at ~3,850 years BCE. This low relative intensity is observed in all samples pertaining to the same respect...

Geochemistry, Geophysics, Geosystems, 2017

Journal of Geophysical Research: Solid Earth, 2017

Speleothems are of interest for high‐resolution reconstruction of the Earth's magnetic field.... more Speleothems are of interest for high‐resolution reconstruction of the Earth's magnetic field. However, little is known about the influence of speleothem morphologies on their natural remanent magnetization (NRM) record. Here we report on a high‐resolution paleomagnetic study of a dome‐shaped speleothem of middle Holocene age from southern Portugal, with special attention to the anisotropy of magnetic susceptibility (AMS) and anisotropy of anhysteretic remanent magnetization (AARM). To assess the potential influence of the slope of the speleothem surface on the recorded remanent magnetization, we compare magnetic directions and AMS and AARM fabrics from subhorizontal to gradually subvertical calcite growth layers collected in a transversal cross section of the speleothem. A linear correlation is observed between magnetic inclinations, calcite laminae slope, and AARM k1 inclination. The AMS fabric is mostly controlled by calcite crystals, with direction of the minimum axes (k3) pe...

Climate of the Past Discussions, 2017

Atlantic Water (AW) advection plays an important role for climatic, oceanographic and environment... more Atlantic Water (AW) advection plays an important role for climatic, oceanographic and environmental conditions in the eastern Arctic. Situated along the only deep connection between the Atlantic and the Arctic Ocean, the Svalbard Archipelago is an ideal location to reconstruct the past AW advection history and document its linkage with local glacier dynamics, as illustrated in the present study of a sedimentary record from Woodfjorden (northern Spitsbergen) spanning the last ~ 15 500 years. Sedimentological, micropalaeontological and geochemical analyses were used to reconstruct changes in marine environmental conditions, sea-ice cover and glacier activity. Data illustrate a partial breakup of the Svalbard–Barents–Sea Ice Sheet from Heinrich Stadial 1 onwards (until ~ 14.6 ka BP). During the Bølling-Allerød (~ 14.6–12.7 ka BP), AW penetrated as a bottom water mass into the fjord system and contributed significantly to the...

Science of The Total Environment, 2016

Quaternary Science Reviews, 2015

IX jene markante Auftau-diskordanz, nachvollziehen. Begrabenes Gletschereis und Grundeis unbekann... more IX jene markante Auftau-diskordanz, nachvollziehen. Begrabenes Gletschereis und Grundeis unbekannter Herkunft mit niedrigen Isotopenwerten (< −30 ‰) scheinen ebenfalls zum Grundeisspektrum von Herschel Island beizutragen, was noch bis vor wenigen Jahren als umstritten galt. Bis in die Gegenwart hinein wurde das Untersuchungsgebiet durch umfassende Küstenerosionsprozesse und anhaltendes Schmelzen von Grundeis beeinflusst. Beide Prozesse haben zu starken geomorphologischen Veränderungen der Landschaft geführt. * Marked samples are not considered within calculations as they represent marginal samples at the transition between ice wedges and adjacent sediments and are supposed to have been affected by isotopic exchange processes.

Hydrology and Earth System Sciences, 2004

Deep Sea Research Part II: Topical Studies in Oceanography, 2002

Scientific Reports

The U-series dating of young and ‘dirty’ speleothems is challenging due to difficulties in assess... more The U-series dating of young and ‘dirty’ speleothems is challenging due to difficulties in assessing the isotopic composition of detrital contaminants and the low-abundance of 230Th generated in situ. Here we propose a new dating approach based on the comparison of a speleothem’s paleomagnetic directions to reference curves from global paleomagnetic reconstructions. This approach is demonstrated on a stalagmite collected from the Soprador do Carvalho cave in the Central Region of Portugal. A radioisotopic age model, built using four U-series ages and three 14C, suggests relatively steady carbonate precipitation from ~ 5760 BCE until ~ 1920 CE. Forty-five 6 mm-thick subsamples were analyzed using alternating field and thermal demagnetization protocols, providing well-defined, primary magnetic directions. An age model of the stalagmite was obtained by fitting its paleomagnetic record with the reference paleosecular variation curves obtained by previous paleo-reconstruction models, app...

The Greenland Ice Sheet (GIS) is the largest storage of freshwater in the Northern Hemisphere. It... more The Greenland Ice Sheet (GIS) is the largest storage of freshwater in the Northern Hemisphere. Its development is closely coupled to the interaction between variations in global climate and ocean circulation. The feedback mechanism between ice sheet and interglacial warming climate is meltwater discharge and enhanced freshwater input into the ocean. The Baffin Bay is an important pathway for Arctic Ocean water and meltwater and therefore freshwater input into the Atlantic Ocean. Melville Bay, a sparsely investigated area within northeast Baffin Bay along the west coast of Greenland, is presently a focus of freshwater input and drains about 27% of the GIS runoff [1]. We investigate potentially changing provenances of silicate detrital material discharged by meltwater into Melville Bay throughout the Holocene. Signatures of radiogenic isotopes strontium (Sr), lead (Pb) and neodymium (Nd) serve as reliable provenance tracers based on their resistance to weathering and transport process...

Paleoceanography and Paleoclimatology, 2020

230Th normalization is a valuable paleoceanographic tool for reconstructing high‐resolution sedim... more 230Th normalization is a valuable paleoceanographic tool for reconstructing high‐resolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more diverse marine environments, the nuances of230Th systematics, with regard to particle type, particle size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records of230Th from across the global ocean at two time slices, the late Holocene (0–5,000 years ago, or 0–5 ka) and the Last Glacial Maximum (18.5–23.5 ka), and investigated the spatial structure of230Th‐normalized mass fluxes. On a global scale, sedimentary mass fluxes were significantly higher during the Last Glacial Maximum (1.79–2.17 g/cm2kyr, 95% confidence) relative to the Holocene (1.48–1.68 g/cm2kyr, 95% confidence). We then examined the potential confounding influences of boundary scavenging, nepheloid layers, hydrothermal scavenging, size‐dependent sed...