The High Arctic LIP in Canada: Trace element and Sm–Nd isotopic evidence for the role of mantle heterogeneity and crustal assimilation

Abstract

The Cretaceous geological evolution of the Canadian Arctic was marked by voluminous magmatism comprising Canada's portion of the High Arctic large igneous province (HALIP) that is thought to have resulted from a mantle plume head. This magmatism is largely recorded as extensive Early Cretaceous lavas of the Isachsen Formation, Late Cretaceous continental flood basalts of the Strand Fiord Formation, and an extensive network of dykes and sills forming their plumbing systems. Axel Heiberg Island near South Fiord contains a small, structurally complex portion of the overall network of HALIP tabular intrusions, from which samples from the South Fiord intrusions and Isachsen Formation basaltic lavas were analysed to better understand their petrogenesis. Specifically, we apply trace-element ratios together with Sm-Nd isotope systematics in order to identify processes that shaped the chemical evolution of the South Fiord intrusions and Isachsen Formation lavas, to identify (1) mantle source chemistries and (2) the role of crustal assimilation. On the basis of Sm-Nd isotopic results, South Fiord intrusion magmas were derived from a homogeneous mantle source whereas a more heterogeneous source is invoked for the Isachsen Formation lavas. Furthermore, modelling with Th/ La, Nb/U, Ba/Th and Ba/Nb suggests that South Fiord intrusive magmatism was contaminated by sedimentary rocks from the Sverdrup Basin. Conversely, a trend towards high Ba/Th in Isachsen Formation lavas suggests a subducted sediment component derived from extinct subduction zones. We surmise that (1) South Fiord intrusive rocks are geochemically distinct from the Isachsen Formation lavas and (2) the HALIP mantle plume head intersected and incorporated sediments from ancestral subduction zones to the present-day Aleutian and Alaska subduction zones to produce the Isachsen Formation flows, whereas the South Fiord intrusions (and correlated Strand Fiord magmatism) were generated from plume material that interacted with upper crustal sedimentary rocks.

Geology of Arctic Margins: Proceedings of ICAM VII 2015

“…Furthermore, modelling with Th/La, Nb/U, Ba/Th and Ba/Nb suggests that South Fiord intrusive magmatism was contaminated by sedimentary rocks from the Sverdrup Basin. Kingsbury et al (2016) conclude that a trend towards high Ba/Th in Isachsen Formation lavas, suggests a subducted sediment component derived from extinct subduction zones. They surmise that South Fiord intrusive rocks are geochemically distinct from the Isachsen Formation lavas, and further that the HALIP mantle plume head intersected and incorporated sediments from ancestral subduction zones to the present-day Aleutian and Alaska subduction zones to produce the Isachsen Formation flows.…”

“…Estrada et al (2016) further find that the northern coast of Ellesmere Island shows some characteristic features of a magma-rich rifted margin indicating an extensional evolution parallel to the North American margin between the openings of the Canada Basin and the Eurasian Basin. On the basis of their Sm-Nd isotopic results, Kingsbury et al (2016) find that South Fiord intrusion magmas were derived from a homogeneous mantle source whereas a more heterogeneous source is invoked for the Isachsen Formation lavas. Furthermore, modelling with Th/La, Nb/U, Ba/Th and Ba/Nb suggests that South Fiord intrusive magmatism was contaminated by sedimentary rocks from the Sverdrup Basin.…”

Geophysical Identification and Characterization of Mafic-Ultramafic Intrusions in Plume Centre Regions

“…Coast intersections (red star, Figure 48), and at Mumbai (white star, Figure 48 The High Arctic Large Igneous Province (HALIP) is a major magmatic event covering more than 1 million km 2 of the High Arctic (e.g., Maher, 2001;Drachev and Saunders, 2006;Buchan and Ernst, 2006;Døssing et al, 2013;Ernst, 2014a;Kingsbury et al 2015). The HALIP is composed of (ferro)gabbroic dykes and sills, and (ferro)basaltic volcanic rocks distributed over Svalbard, Franz…”

“…While the Wootton intrusion was emplaced during the second stage of HALIP magmatism, the intrusion on western Ellesmere Island was likely emplaced during the first stage (129-127 Ma) (e.g. Corfu et al 2013;Jowitt et al, 2014;Kingsbury et al, 2015), given that it is overlain by volcanic and plutonic rocks that were emplaced during the first stage and which were likely sourced from the deeper body.…”

Hot Rocks from Cold Places: A Field, Geochemical and Geochronological Study from the High Arctic Large Igneous Province (HALIP) at Axel Heiberg Island, Nunavut

“…Relative to the number of early K-Ar and 40 Ar/ 39 Ar age determinations, the number of highly precise U-Pb ages from the High Arctic LIP is small but expanding, enabling refinement on magmatic and volcanic episodes linked to the High Arctic LIP ( Ma are compiled from datasets derived from (Patchett et al, 2004) in the case of the Sverdrup Basin and (Patchett et al, 1999) for the Franklin Mobile Belt and cratonic proxy. These formed the basis for crustal contamination models used in Chapter 3 (Kingsbury et al, 2016). For the Sverdrup Basin, units older than and including the Christopher Formation of 110 Ma (Patchett et al, 2004) were used in the calculation.…”