Pierre Francus

Institut National de la Recherche Scientifique | INRS · Eau Terre Environnement Centre

Summer cooling is one of the most direct consequences of explosive volcanic eruptions that can affect ecosystems and human societies. Recent studies revealed a multi-year cooling impact on hemispheric and global summer temperatures after tropical eruptions, yet, the volcanic responses appear to vary on regional scales. Here, we revisit volcano-indu...

Covering 55% of Canada’s total surface area and stretching from coast to coast to coast, the Canadian boreal zone is crucial to the nation’s economic and ecological integrity. Although often viewed as relatively underdeveloped, it is vulnerable to numerous stressors such as mining, forestry, and anthropogenic climate change. Natural archives preser...

The natural remanent magnetization (NRM) of high sedimentation rate sediments provides significant information about paleomagnetic secular variation of the Earth's magnetic field and can also potentially be used for stratigraphy. However, NRM acquisition depends on conditions inherent to the depositional environment. In addition to recording a prec...

Acidification and eutrophication are common limnological stressors impacting many water bodies across the globe. While the negative impacts of these stressors on limnetic communities are generally known, their influence on the accumulation of specific sediment constituents, such as metals, remains unclear. Benefitting from past research and long-te...

Dual-energy CT (DECT) consists in imaging objects using two X-ray incident beams with different energies to discriminate and identify the phases within a sample based on its density (electron density, ρe) and elemental composition (effective atomic number, Zeff). Here, a stoichiometric calibration method, originally developed for medical purposes a...

This paper reports a new experimental method applying medical X-ray computed tomography (CT) to estimate the bedload in sand transport. A set of current-generated sand ripple experiments were conducted in a small hydraulic flume inserted in the CT scanner. The methodology is based on the measurements of height, velocity and density of bedforms to e...

Palynological and sedimentological analyses were performed on the sediment core HH16‐1205‐GC retrieved from the central Isfjorden, West Spitsbergen. The sequence, which spans the last 7000 years, revealed an overall cooling trend with an important climate shift between 4.4 and 3.8 cal. ka BP, in addition to millennial‐scale oscillations. Sea‐surfac...

Dual-energy CT (DECT) consists in imaging objects using two X-ray incident beams with different energies in order to discriminate and identify the different phases within a sample based on their density (specifically electron density, ρe) and elemental composition (effective atomic number, Zeff). Here, a stoichiometric calibration method, originall...

1. Introduction The dual-energy CT (DECT) scanning consists in imaging objects with two different X-ray spectra and in combining the results to achieve the discrimination and the identification of materials based on their density and elemental composition [1]. Here, a stoichiometric calibration method, originally developed for medical purposes [2]...

X-ray computed tomography coupled to the automated data analysis tool FragFinder was used to study six targets impacted by 11 different projectiles. Extracted projectile DOP, volumes, and densities provided a sufficient database for predicting impact velocity. The obtained precision is estimated to be in the range of ± 12 % with similar contributio...

Lake sedimentation rate represents a synthetic metric of ecosystem functioning. Many localized studies have reported a significant association between land use/land cover changes and lake sediment mass accumulation rates, with a few global syntheses echoing these findings at larger scales. In the literature, studies evaluating lead‐210 (210Pb) for...

Medical CT-scanners measure the X-rays attenuation that go through a sample allowing the non-destructive 3D internal structure visualization of a wide range of objects. The attenuation depends on the interaction between incident beam and sample density and chemical composition. By scanning specimens using two different energies (low and high), the...

In this work, a novel physics-rich beam-hardening correction algorithm was developed for X-ray Computed Tomography. This method uses the spectrum information, the detector response, the filter geometry and a calibration curve. The correction, which does not require prior material knowledge, was embedded in an iterative reconstruction algorithm, and...

Medical X-ray computed tomography (CT) can be used to rapidly and non-destructively characterize structure and density variations of geological specimens. More information about the nature of samples (electron density and elemental composition) can be retrieved using multi-spectral approaches. This paper explores one of them, a stoichiometric calib...

This paper presents a new annually laminated record (varves) from Lake Walker, Québec North Shore (eastern Canada) spanning the period from ~ 3230 to 2320 ± 20 cal BP. A ~ 3.5-m-long composite sequence was established with the best regular and continuous laminated intervals using computed tomography and high-resolution photographs. The varve chrono...

Sediment Accumulation Rate (SAR; measured as mm yr−1) and Mass Accumulation Rate (MAR; measured as g cm−2 yr−1) data were collected from published lake core records that spanned the past ~ 150 years, from approximately 500 sites worldwide. For each lake, key watershed characteristics including watershed size, slope, land use and climate were extrac...

Boreal Québec is one of the regions of the world where climate change has been the most marked over the past thirty years. The climate has warmed up, but also dried up, with a drop of more than 15% in annual precipitation. The situation could have serious socio-economic conse-quences as nearly 50% of the province's hydroelectric production comes pr...

Analysis of short sediment cores collected in Grand Lake, Labrador, revealed that this lake is an excellent candidate for the preservation of a laminated sediment record. The great depth of Grand Lake, the availability of fine sediments along its tributaries and its important seasonal river inflow have favoured the formation of a 160-year-long clas...

Global warming due to anthropogenic factors can be amplified or dampened by natural climate oscillations, especially those involving sea surface temperatures (SSTs) in the North Atlantic which vary on a multidecadal scale (Atlantic multidecadal variability, AMV). Because the instrumental record of AMV is short, long-term behavior of AMV is unknown,...

Stoco Lake (Tweed, Ontario, Canada) has a history of industrial contamination and is heavily influenced by inflow from the Moira River. Stoco Lake is frequently affected by nuisance algal blooms (including cyanobacteria), which have largely been attributed to cultural eutrophication. To further our understanding of the environmental dynamics of Sto...

Analysis of short sediment cores collected in Grand Lake, Labrador, revealed that this lake is an excellent candidate for the preservation of laminated sediments record. The great depth of Grand Lake, the availability of fine sediments along its tributaries, and its important seasonal river inflow have favored the formation of a 160 years-long clas...

X-ray computed tomography (CT) is a powerful and non-destructive technique that allows visualization of objects internal structure (Mees et al., 2003). The resulting cross section is a single grayscale image corresponding to a generic attenuation of the material (μ), without having the possibility of separating the two influencing properties (densi...

High‐resolution multibeam bathymetric data and acoustic sub‐bottom profiles were recently collected in Grand Lake (Labrador), one of the deepest lake basins in eastern North America, to reconstruct: (1) the retreat of the Laurentide Ice Sheet (LIS) west of Lake Melville, and (2) the history of sedimentation since deglaciation in this 54‐km long, 3‐...

Significance Using a compilation of ¹⁴ C and pollen data of lake sediment records from over 632 sites globally, we identified the timings of first increase in lake sedimentation. Changes in lake sediment rates at this time are closely linked to increased sediment supply from hillslope erosion. The analysis on the relative roles of the driving facto...

The progress of science is tied to the standardization of measurements, instruments, and data. This is especially true in the Big Data age, where analyzing large data volumes critically hinges on the data being standardized. Accordingly, the lack of community-sanctioned data standards in paleoclimatology has largely precluded the benefits of Big Da...

Few annually laminated (varved) lacustrine records exist in the Arctic, but these high-resolution climate archives are needed to better understand abrupt climate change and the natural mode of climate variability of this sensitive region. This paper presents a new high-resolution 2900-year long varved lake sediment record from the Fosheim Peninsula...

This Data in Brief article presents sedimentological and geochemical parameters from a set of sedimentary samples collected in the Saint-Charles River, a tributary of the Saint-Lawrence River flowing in Québec City (QC, Canada). It details the experimental design, methods, materials and results of destructive analyses related to a multi-proxy study...

Although computed tomography (CT-Scanning) has been regularly applied to core analyses in petroleum geology, there is still a need to improve our ways to document porosity and porosity distribution in the entire pore scale spectrum, from the tens of nanometer to the meter-scale. Porosity imaging is particularly crucial for complex and heterogeneous...

Micromorphology is the study of arrangements of particles and matrix and is primarily carried out using thin sections. It is a useful tool to characterize sedimentary facies because material is not disaggregated and the particles are examined in their original position relative to other particles, thus increasing the reliability of sedimentological...

Québec City (QC, Canada) is an important urban center developed along the Saint-Charles River, at the confluence with the Saint-Lawrence River. Here, environmental issues related to pollution have been recently raised for sediments trapped upstream a dam built in the early 1970s. The major concern is about downstream transport of sediments and cont...

This PAGES (Past Global Changes) 2k (climate of the past 2000 years working group) special issue of Climate of the Past brings together the latest understanding of regional change and impacts from PAGES 2k groups across a range of proxies and regions. The special issue has emerged from a need to determine the magnitude and rate of change of regiona...

This PAGES (Past Global Changes) 2k (Climate of the past 2000 years Working Group) Special Issue of Climate of the Past brings together the latest understanding of regional change and impacts from PAGES 2k groups across a range of proxies and regions. The Special Issue has emerged from a need to determine the magnitude and rate of change of regiona...

This study used signal-to-noise ratios to assess the effects of increasing Itrax XRF instrument parameters, namely tube voltage, tube current and exposure time, on XRF spectra and measurement repeatability. Tests were performed on cores from British and Irish floodplains. Seven combinations of tube voltage and current and six exposure times were co...

The coupling of unmanned aerial systems (UAS) with Structure-from-Motion (SfM) photogrammetry allows rapid and inexpensive 3D field imagery. This method was used to quantify sediment transport in an urban river flowing in downtown Quebec City (Saint-Charles River). The aim was to evaluate the impact of dam management operations at the outlet (i.e.,...

In this article, the first spatially resolved and millennium-length summer (June–August) temperature reconstruction over the Arctic and sub-Arctic domain (north of 60° N) is presented. It is based on a set of 44 annually dated temperature-sensitive proxy archives of various types from the revised PAGES2k database supplemented with six new recently...

Reanalysis data show an increasing trend in Arctic precipitation over the 20th century, but changes are not homogenous across seasons or space. The observed hydroclimate changes are expected to continue and possibly accelerate in the coming century, not only affecting pan-Arctic natural ecosystems and human activities, but also lower latitudes thro...

Introduction As part of a new Industry-Academy research partnership, this project intended to assess the reservoir potential of lower Silurian carbonates (Sayabec Formation) within a prospective play (Massé Structure) in the lower St-Lawrence river area. Carbonate reservoirs are known to be genetically complex and spatially heterogenous (bioclasts,...

Lake sediments constitute natural archives of past environmental changes. Historically, research has focused mainly on generating regional climate records, but records of human impacts caused by land use and exploitation of freshwater resources are now attracting scientific and management interests. Long-term environmental records are useful to est...

This paper analyzes short gravity cores sampled along transects in three adjacent deep fjord-lakes (lakes Pentecôte, Walker, and Pasteur) on the Québec North Shore, eastern Canada, to evaluate the distribution of laminated sediments and potential for varve formation. Facies analysis based on lithological description, digital photos, CT-scan images,...

Geothermal energy resources are now being developed in non-magmatic areas, particularly in sedimentary basins. In such contexts, geothermal energy can be produced locally, near consumers, as individual or industrial heat production facility from deep water well. Conventional methods applied to oil and gas reservoirs are revisited in the present pro...

Lake sediments constitute natural archives of past environmental changes. Historically, research has focused mainly on generating regional climate records, but records of human impacts caused by land use and exploitation of freshwater resources are now attracting scientific and management interests. Long-term environmental records are useful to est...

Lake sediments constitute natural archives of past environmental changes. Historically, research has focussed mainly on generating regional climate records, but records of human impacts caused by land-use and exploitation of freshwater resources are now attracting scientific and management interests. Long-term environmental records are useful to es...

Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all conti...

The evolution of deltas and submarine fans is often envisioned as largely controlled by relative sea-level variations. However, in some cases, relative sea level can have less effect on delta and submarine fan activity than sediment supply and shelf geomorphology. In order to document the relative importance of these three factors on deltaic and su...

Understanding how internal climate variability influences arctic regions is required to better forecast future global climate variations. This paper investigates an annually-laminated (varved) record from the western Canadian Arctic and finds that the varves are negatively correlated with both the instrumental Pacific Decadal Oscillation (PDO) duri...

Understanding how internal climate variability influences arctic regions is required to better forecast future global climate variations. This paper investigates an annually-laminated (varved) record from the western Cana-dian Arctic and finds that the varves are negatively correlated with both the instrumental Pacific Decadal Oscillation (PDO) dur...

Mobiliers archéologiques et sédiments qui les recèlent sont des témoignages fugaces qu’il convient d’analyser, de préserver et de valoriser. Ces dernières années, se sont beaucoup développées des méthodes de numérisation qui apportent des solutions non destructives de conservation, d’analyse et de diffusion du patrimoine archéologique. Cependant, c...

In this article, the first spatially resolved millennium-long summer (June–August) temperature reconstruction over the Arctic and Subarctic domain (north of 60° N) is presented. It is based on a set of 54 annually dated temperature sensitive proxy archives of various types, mainly from the updated and revised PAGES2k database supplemented with 6 ne...

Along with Arctic amplification, changes in Arctic hydroclimate have become increasingly apparent. Reanalysis data show increasing trends in Arctic temperature and precipitation over the 20th century, but changes are not homogenous across seasons or space. The observed hydroclimate changes are expected to continue, and possibly accelerate, in the c...

This paper presents the first detailed paleoclimate reconstruction of the latest Antarctic isotope maximum (AIM4, ~ 33–29 ka cal. BP) at 52°S in continental southeastern Argentine Patagonia. High-resolution sedimentological and geochemical analyses of sediments from the maar lake Potrok Aike (PTA) reveal a decrease in the thickness of flood-induced...

It is well established that the Arctic strongly influences global climate through positive feedback processes, one of the most effective being the sea-ice – albedo feedback. Understanding the region’s sensitivity to both internal and external forcings is a prerequisite to better forecast future global climate variations. Here, sedimentological evid...

It is well established that the Arctic strongly influences global climate through positive feedback processes (Cohen et al., 2014), one of the most effective being the sea-ice – albedo feedback (Screen et al., 2010). Understanding the region’s sensitivity to both internal and external forcings is a prerequisite to better forecast future global clim...

Significance Using a compilation of data arising from over 1,500 European watersheds, we have identified the relative role of different drivers in initiating hypolimnetic hypoxia, a critical indicator of lake health. In particular, our regional synthesis of laminated lake sediments indicated a significant acceleration in the spread of lacustrine hy...

Downcore counting of laminations in varved sediments offers a direct and incremental dating technique for high-resolution climatic and environmental archives with at least annual and sometimes even seasonal resolution 1,2. Once a varve chronology is established it can be applied to precisely date events like volcanic ash layers, earthquakes or huma...

High Arctic lakes are commonly used for paleoclimatic reconstructions because they are particularly sensitive to climate variability. However, the processes leading to sediment deposition and distribution in these lakes are often poorly understood. Here, for the first time in the Canadian High Arctic, we present original data resulting from swath b...

A small scale physical model of a river and its bed was built to study sediment transport. This model was installed through a CT scanner in order to validate a data acquisition system coupling a CT scan and a particle image velocimetry (PIV) system. The PIV structure is fixed to the scanner, which moves along 2.6 meters rails. This combined system...