Alessandro Ielpi

Alessandro Ielpi
Laurentian University · Department of Earth Sciences

Doctor of Philosophy

About

98
Publications
36,199
Reads
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1,307
Citations
Introduction
I am a sedimentologist and geomorphologist with expertise on early Earth's rivers and remote sensing of modern and ancient sedimentary basins. My research is mostly field-based, with study areas located in the Canadian Arctic, the Great Basin of western US, and the North American Cordillera. My research also involves geophysical modelling aimed at resolving watershed biogeochemistry and surface processes of early Earth and Mars.
Additional affiliations
January 2016 - present
Laurentian University
Position
  • Professor (Assistant)
Education
September 2009 - June 2013
Università degli Studi di Siena
Field of study
  • Sedimentology
January 2007 - June 2009
Università degli Studi di Siena
Field of study
  • Applied Geology
September 2003 - December 2006
Università degli Studi di Siena
Field of study
  • Geotechnologies

Publications

Publications (98)
Article
Full-text available
Proterozoic rivers flowed through barren landscapes, and lacked interactions with macroscopic organisms. It is widely held that, in the absence of vegetation, fluvial systems featured barely entrenched channels that promptly widened over floodplains during floods. This hypothesis has never been tested because of an enduring lack of Precambrian fluv...
Article
Full-text available
Meandering rivers are diagnostic landforms of hydrologically active planets, and their migration regulates the continental component of biogeochemical cycles that stabilize climate and allow for life on Earth. The rise of river meanders on Earth has been linked to riverbank stabilization driven by the Palaeozoic evolution of plant life about 440 mi...
Article
River bends occasionally meander to the point of cutoff, whereby a river shortcuts itself and isolates a portion of its course. This fundamental process fingerprints a river’s long‐term planform geometry, its stratigraphic record, and biogeochemical fluxes in the floodplain. Although meander cutoffs are common in fast‐migrating channels, timelapse...
Article
Full-text available
The Palaeozoic evolution of land plants revolutionized river geomorphology. However, the relationships between biotic forcing and channel dynamics are still debated and, as such, the impacts of anthropogenic stressors such as climate change, reduced biodiversity and aridification on modern meandering rivers and their biogeochemical fluxes remain po...
Article
Lateral migration is a key process shaping sinuous rivers and controlling sediment exchange with floodplains. The rate at which channels migrate is affected by bend curvature, bank erodibility, and sediment supply. The relationship between migration rate and sediment supply is poorly understood in dryland regions, where direct measurements are scar...
Article
As Mars transitioned from an early Earth-like state to the cold desert planet it is today, it preserved a near pristine record of surface environments in a world without plate tectonics and complex life. The records of Mars’ Earth-like surfaces have remained largely untouched for billions of years, enabling space exploration to provide critical ins...
Article
Reconstructing Precambrian sedimentary environments over broad cratonic regions often relies on a combination of facies, structural, and provenance analyses. The Mesoproterozoic (ca. 1270–1090 Ma) Fury and Hecla Group, exposed on the Melville Peninsula and northern Baffin Island (Nunavut, Canada), is considered broadly correlative with strata of th...
Article
The synoptic analysis of coeval orogens and sedimentary basins is crucial to our understanding of Earth’s crustal and surface processes. The Nonacho Group (Northwest Territories, Canada) is a major and yet enigmatic clastic sedimentary unit part of a basin system preserved over >2300 km along its original continental-sloping direction. This basin s...
Article
Full-text available
The terminal Mesoproterozoic was a period of widespread tectonic convergence globally, culminating in the amalgamation of the Rodinia supercontinent. However, in Laurentia, long-lived orogenesis on its eastern margin was punctuated by short-lived extension that generated the Midcontinent Rift ca. 1110–1090 Ma. Whereas this cratonic rift basin is ty...
Article
The characterization of ancient fluvial‐channel bars informs predictions of sedimentary facies distribution, and hence they are critical for interpreting river morphodynamics through time. Within active fluvial channels, sediment storage occurs along the banks or along their axial portion, generating bank‐attached or mid‐channel bars, respectively....
Article
Determining when continental masses emerged above the global ocean is crucial to understanding secular changes in crustal and Earth-surface processes. The emergence of continents above sea level provided important sinks for atmospheric CO2, a source of bioavailable P2O5, and initiated the erosional component of the rock cycle. Previous estimates fo...
Article
Establishing critical comparisons between fluvial- and tidal-channel morphodynamics is a major goal in the study of coastal landscapes. Freely migrating meandering rivers are known to produce laterally extensive, sand-prone point-bar bodies which commonly exhibit width:thickness ratios up to 250. Meandering channels are widespread in tidal channel...
Article
Full-text available
Although there is little doubt that rivers once flowed on Mars' surface, how sustained and frequent their flows were remains enigmatic. Understanding the hydrology of early Mars, nonetheless, is a prerequisite to resolving the planet's climate history and the astrobiological potential of various ancient putative ecosystems. In 2021, NASA's Persever...
Technical Report
Full-text available
This paper presents new field observations collected during five weeks of Precambrian bedrock mapping in summer 2018 in the area north of Fury and Hecla Strait on northwestern Baffin Island, Nunavut, and preliminary correlations with rock units in neighbouring areas. Basement rocks, all presumed to be Archean in age, include tonalite-granodiorite o...
Technical Report
Full-text available
Sedimentary rocks of Meso-to Neoproterozoic age exposed in northern Nunavut accumulated during the amalgamation of the supercontinent Rodinia and preserve key fossils recording the evolution of eukaryotic life. The Fury and Hecla Basin is a poorly understood remnant of the late Mesoproterozoic Bylot basin system, which also includes the Borden, Thu...
Article
The links between flood frequency and rates of channel migration are poorly defined in the ephemeral rivers typical of arid regions. Exploring these links in desert fluvial landscapes would augment our understanding of watershed biogeochemistry and river morphogenesis on early Earth, i.e., prior to the greening of landmasses. Accordingly, we analys...
Article
Braided rivers have accumulated a dominant fraction of the terrestrial sedimentary record, and yet their morphodynamics in proximal intermountain reaches are still not fully documented—a shortcoming that hampers a full understanding of sediment fluxes and stratigraphic preservation in proximal-basin tracts. Located in the eastern Canadian Cordiller...
Article
Full-text available
Flume experiments and field observations show that bank vegetation promotes the formation of narrow and deep single‐thread channels by strengthening riverbanks. Consistent with this idea, the pre‐Silurian fluvial record generally consists of wide monotonous sand bodies often interpreted as deposits of shallow braided rivers, whereas single‐thread r...
Conference Paper
Full-text available
The late Mesoproterozoic Bylot basins, comprising the Borden, Hunting-Aston, Fury and Hecla, and Thule basins, have proven critical in establishing the timing of the rise of photosynthesis among eukaryotes and secular changes in marine geochemistry. Correlations between the individual basins have historically been founded on lithostratigraphic simi...
Article
Modern meandering streams devoid of plant life have long been ignored despite their relevance to the study of sedimentary landscapes in the long span of Earth’s history that preceded the greening of continents. We present a sedimentologic and remote-sensing analysis of the McLeod Springs Wash, a small-scale, endorheic, and barren fluvial fan in the...
Chapter
Full-text available
The Fury and Hecla Group is a Mesoproterozoic sedimentary succession exposed on northern Baffin Island and northern Melville Peninsula, Nunavut. Part of the Bylot basins, the Fury and Hecla Basin comprises sedimentary and mafic assemblages, and nonconformably overlies Archean to late Paleoproterozoic basement rocks of the Rae craton. Sandstone attr...
Chapter
Full-text available
During the 2017 field season, sedimentological and stratigraphic work was conducted within the Kilohigok Basin, located in the Kitikmeot Region of Nunavut. The Kilohigok Basin has been the subject of a few previous field projects; however, its lowermost stratigraphic interval-the Kimerot Group-has not so far been the focus of a detailed study. The...
Technical Report
Full-text available
Recent geochronological, chemostratigraphic and paleontological studies from the Mesoproterozoic Bylot Supergroup of the Borden Basin in northern Baffin and Bylot islands offer critical insights into the evolution of a late Mesoproterozoic intracratonic basin system and the origin of photosynthetic eukaryotes therein. Located in northeastern Canada...
Article
Vegetation-free fluvial meanders are exceptional on modern Earth, and their abundance in pre-Silurian rock records is debated. Whether or not landscapes devoid of plant life could sustain sinuous planforms is nonetheless a fundamental concept that could disclose parallels with extraterrestrial sedimentary realms. The sedimentology and morphometry o...
Chapter
Full-text available
Lacking evidence for fluvial lateral‐accretion elements in early Palaeozoic systems has been ascribed to an absence of binding by rooted vegetation on subaerial landscapes. Transposing this thesis to earlier geological times, it has been proposed that, likewise, Precambrian landscapes could not have sustained highly sinuous fluvial networks. This p...
Article
The study of geomorphic processes in barren landscapes, Precambrian and modern, has wide implications for planetary science. A long‐held status quo has been that, prior to the Palaeozoic evolution of vegetation, fluvial channels would have been invariably shallow, wide, braided in planform and flashier in discharge than vegetated ones. These assump...
Article
Fluvial floodplains established prior to the greening of continents have long been overlooked, despite their relevance for landscape reconstructions in deep time. The record of fluvial overbank sedimentation dates back as far as the Mesoarchean, and mature assemblages of floodplain landforms had already developed at least by the early Palaeoprotero...
Article
We present detrital zircon U-Pb data from mainly fluvial sandstones of the Mackenzie Mountains Supergroup, Yukon (four samples), and the Shaler Supergroup, Northwest Territories (seven samples). The high similarity of data sets from widely separated units supports long-held stratigraphic correlations between the late Mesoproterozoic Neoproterozoic...
Article
The interpretation of climate regimes from facies analysis of Precambrian clastic rocks has been challenging thus far, hindering full reconstructions of landscape dynamics in pre-vegetation environments. Yet, comparisons between different and co-active sedimentary realms, including fluvial-channelised, floodplain, and aeolian hold the potential to...
Data
Geometric data for the Proterozoic channel forms analysed in this study.
Data
Geometric data, compiled from literature, for the Ordovician-Pleistocene channel forms analysed in this study.
Data
Geometric data, compiled from literature, for the modern perennial river cross-sections analysed in this study.
Article
Pre-vegetation fluvial channels have long been considered predominantly sheet-like in geometry, owing to hydraulic sections that rapidly widened rather than incise during floods. This motif has been paralleled to that of modern dryland rivers subject to sharp discharge fluctuations during ephemeral floods. However, a number of Precambrian fluvial s...
Article
Vegetation exerts strong controls on fluvial sinuosity, providing bank stability and buffering surface runoff. These controls are manifest in densely vegetated landscapes, whereas sparsely vegetated fluvial systems have been so far overlooked. This study integrates remote sensing and gauging records of the meandering to wandering Fossálar River, a...
Article
Full-text available
We present the results of helicopter-and field-based geological mapping of Elu Inlet and Melville Sound, Kitikmeot Region of Nunavut, Arctic Canada. The area includes a ∼150 km-wide belt of Proterozoic sedimentary rocks that unconformably overlie the Archean Slave Province of the Canadian Shield and are cross-cut by Neoproterozoic mafic rocks and c...
Article
The current paradigm on Precambrian fluvial sedimentology assumes that pre-vegetation environments did not allow for the establishment of deep, stable channels. However, few studies have documented a continuum of fluvial-depositional architectures along km-scale transects where clusters of channel bodies can be observed in their entirety. The Stoer...
Article
Modern unvegetated rivers flowing through aeolian-dune fields demonstrate potential as analogues for pre-vegetation fluvial landscapes. A prominent example is contained in the Lençóis Maranhenses of Brazil, a coastal aeolian system hosting the semi-perennial Rio Negro. Remotely sensed images covering c. 45 years display the rhythmic expansion and w...
Article
Spectacular canyon exposures of the ~ 1 Ga Nelson Head Formation along the modern Brock River, Northwest Territories, provide a rare opportunity to assess the deposits of pre-vegetation, braided to sinuous channelized fluvial systems. We analyze the sedimentology, architecture, and depositional evolution of 16 stacked fluvial-channel belts at this...
Article
The overwhelming documentation of coarse-grained alluvial fans dominated by mass flow contrasts with the scarce accounts of finer grained, traction-dominated alluvial fans. To fill this gap, we present sedimentological and architectural data from a set of sand-rich, streamflow-dominated Pleistocene fans flanking the eastern Upper Valdarno Basin, It...
Article
The repetitive sedimentology of many Precambrian sheet-dominated fluvial sandstones favoured their attribution to unconfined depositional processes. This article presents outcrop evidence for deep channelled drainage in the 1.9 Ga Burnside River Formation of Kilohigok Basin, Arctic Canada. On the ground, sheet-like sandbodies with ubiquitous cross-...
Article
Classical models developed for ancient fluvial point bars are based on the assumption that meander bends invariably increase their radius as meander-bend apices migrate in a direction transverse to the channel-belt axis (i.e., meander bend expansion). However, many modern meandering rivers are also characterized by down-valley migration of the bend...
Article
We present a 1:10,000 scale geological map for the southeastern sector of the Volterra Basin (Northern Apennines, Italy), together with supporting stratigraphic-structural data. The Volterra Basin consists of a major structural depression within the Northern Apennines hinterland, NNW-SSE-oriented and filled with more than 2000 m of late Miocene-Qua...
Technical Report
Full-text available
Elu Inlet and Tariyunnuaq (Melville Sound) are located in the Kitikmeot Region of Nunavut (Canada), and are underlain by a succession of Paleo- to Mesoproterozoic sedimentary rocks known as the Elu and Kilohigok basins. This paper focuses on the stratigraphy and gamma-ray spectrometry of the northeastern margin of the Kilohigok Basin, which is expo...
Article
Assessments of depositional architecture and paleodrainage in planform are increasingly recognized as critical for the reconstruction of ancient fluvial morphodynamics; however, planview exposures of ancient, undeformed meandering-fluvial deposits are scattered, and exceptional occurrences such as the exhumed meander plain of the Scalby Formation (...
Article
Riparian vegetation profoundly influences modern fluvial channels in a variety of ways, depending on the life-history strategies of different plant types, disturbance frequency, and drainage conditions of available habitats. Direct evidence for these dynamic relationships is usually cryptic in ancient deposits. We report evidence for interactions b...
Article
The sedimentary products of forty-three Neoproterozoic fluvial-channel belts are superbly exposed along the seaboard of Stoer Peninsula, Scotland, UK. The deposits belong to the Applecross Formation, part of the Torridonian succession, and their planview style and palaeodrainage are reconstructed at three sites. In-channel deposits record both acti...
Article
Precambrian fluvial deposits have been traditionally described as architecturally simple, forming shallow and wide braidplains with sheet-like geometry. The varied architecture and morphodynamics of the 1.6 Ga Ellice Formation of Elu Basin, Nunavut, Canada, are examined from detailed studies of section and planform exposures along coastal platforms...
Technical Report
Full-text available
This work was part of the Geo-mapping for Energy and Minerals (GEM) Program in the Elu Basin area. It is being co-led by the Geological Survey of Canada (GSC) and the Canada-Nunavut Geoscience Office. The study area comprises National Topographic System map area 77A. The objective of this work is to improve the sedimentological framework within the...
Technical Report
Full-text available
This work was part of the Geo-mapping for Energy and Minerals (GEM) Program in the Elu Basin area. It is being co-led by the Geological Survey of Canada (GSC) and the Canada-Nunavut Geoscience Office. The study area comprises National Topographic System map area 77A. The objective of this work is to improve the sedimentological framework within the...
Conference Paper
Paleogeographic reconstructions based on detrital-zircon geochronology and sedimentary provenance depict continental-scale rivers that drained the Grenville Orogen at around 1 Ga over thousands of km. River networks within foreland and intermountain basins laid down deposits that today form iconic landscapes of the British Caledonides and Canadian...
Article
Full-text available
The 1125-m-thick type section of the Pennsylvanian Boss Point Formation is well exposed along the shore of the Bay of Fundy in Nova Scotia. We provide the first comprehensive account of the entirety of this formation, which comprises nearly one-third of the stratigraphic thickness of the Joggins Fossil Cliffs UNESCO World Heritage Site. The basal C...
Article
As vegetation evolved during the Palaeozoic Era, terrestrial landscapes were substantially transformed, especially during the ~120 million year interval from the Devonian through the Carboniferous. Early Palaeozoic river systems were of sheet-braided style – broad, shallow, sandbed rivers with non-cohesive and readily eroded banks. Under the influe...
Article
Vegetation is a major driver of fluvial dynamics in modern rivers, but few facies models incorporate its influence. This article partially fills that gap by documenting the stratigraphy, architecture and palaeobotany of the Lower Pennsylvanian Boss Point Formation of Atlantic Canada, which contains some of the Earth’s earliest accumulations of larg...
Article
We present a 1:10,000 scale geological map for the south-eastern sector of the Volterra Basin (Northern Apennines, Italy), together with supporting stratigraphic-structural data. The Volterra Basin consists of a major structural depression within the Northern Apennines hinterland, NNW-SSE-oriented and filled with more than 2000 m of late Miocene-Qu...