Geology, simplified tectonic assemblage map of the Canadian Arctic Islands, Northwest Territories - Nunavut

Abstract

This map and geodatabase illustrate the geology of the Canadian Arctic Islands including all lands north and west of Baffin Island. Major features include high-grade Archean and Paleoproterozoic metasedimentary and granitoid rocks of Ellesmere and lands to south and southwest. To the north and west is Cambrian to Devonian cover that grades to deformed rocks of the Ellesmerian Orogen on Ellesmere Island and in the central and western Arctic Islands. The Ellesmerian Orogen features Devonian molasse detached on Ordovician evaporites, outer shelf carbonates of Ellesmere Island detached in the Neoproterozoic, deep water strata including volcanics and turbidites, and Pearya terrane, accreted to ancestral North America in the Silurian. Unconformable on all this are Carboniferous to Paleogene strata of Sverdrup Basin which features a second deformation belt of Paleogene age, the Eurekan Orogen. Youngest rocks are Neogene and widely represented in the western Arctic Islands from Meighen to Banks islands.

Basal thermal regime affects the biogeochemistry of subglacial systems

“…Therefore, unlike the 'warm' basal ice that forms and persists at the beds of the faster-flowing glaciers, the basal ice at the Western Margin is likely below the pressure melting point and is referred to here as 'cold' basal ice. Although located up to ~100 km apart, the three fast-flowing glaciers explored in this study are all underlain by metasedimentary rocks and gneiss, while ice at the Western Margin is largely underlain by sandstone, dolomite and limestone bedrock (Harrison et al, 2016) (Fig. 1).…”

“…The 'cold' basal ice from the Western Margin had relatively high concentrations of TDP, TDN (particularly NH 4 + ) ( Table 1, Fig. 3) while the 'warm' basal ice samples were only occasionally enriched in reduced nitrogen (NH 4 + ) and dissolved phosphorus (TDP) ( Table 2). The substrate surrounding the Western Margin sample sites is composed largely of Cambrian and Ordovician sandstone, dolomite, limestone, and conglomerate (Harrison et al, 2016), which likely contain higher phosphorus https://doi.org/10.5194/bg-2019-317 Preprint. Discussion started: 9 September 2019 c Author(s) 2019.…”

Basal thermal regime affects the biogeochemistry of subglacial systems

“…with basal ice, subglacial water, and sediments, its geochemistry (Tranter et al, 2002), nutrient content (Hawkings et al, 2014;Wadham et al, 2016), and microbial community composition (Dubnick et al, 2017) are dramatically altered. Direct links have recently been established between subglacial biogeochemical signatures and impacts on downstream environments, including downstream freshwater (Sheik et al, 2015) and fjord ecosystems (Gutiérrez et al, 2015).…”

Radar sounding survey over Devon Ice Cap indicates the potential for a diverse hypersaline subglacial hydrological environment

“…The features identified as subglacial lakes are situated in two bedrock troughs (T1 and T2) in the cold-based interior of the ice cap (Burgess et al, 2005;Van Wychen et al, 2017;Paterson and Clarke, 1978) where basal ice temperatures are expected to be well below the pressure-melting point of ice (Figure 1). The brine-rich fluid of the lakes is hypothesized to originate from the dissolution of a salt-bearing geological unit, referred to as the Bay Fiord Formation and abbreviated as Ocb (Harrison et al, 2016;Mayr, 1980;Thorsteinsson and Mayr, 1987) that is projected to outcrop at the ice-bed interface in the vicinity of the subglacial lakes (Rutishauser et al, 2018).…”