Paleomagnetism and U–Pb geochronology of the Clarence Head dykes, Arctic Canada: orthogonal emplacement of mafic dykes in a large igneous province

2009 ◽  
Vol 46 (3) ◽  
pp. 155-167 ◽  
Author(s):  
Steven W. Denyszyn ◽  
Don W. Davis ◽  
Henry C. Halls
Keyword(s):  
Remanent Magnetization ◽  
High Arctic ◽  
Large Igneous Province ◽  
Dyke Swarm ◽  
Canadian High Arctic ◽  
The North ◽  
Igneous Province ◽  
The Difference ◽  
Age Range ◽  
Chemical Remanent Magnetization

The north–south-trending Clarence Head dyke swarm, located on Devon and Ellesmere Islands in the Canadian High Arctic, has a trend orthogonal to that of the Neoproterozoic Franklin swarm that surrounds it. The Clarence Head dykes are dated by the U–Pb method on baddeleyite to between 716 ± 1 and 713 ± 1 Ma, ages apparently younger than, but within the published age range of, the Franklin dykes. Alpha recoil in baddeleyite is considered as a possible explanation for the difference in ages, but a comparison of the U–Pb ages of grains of equal size from both swarms suggests that recoil distances in baddeleyite are lower than those in zircon and that the Clarence Head dykes are indeed a distinctly younger event within the period of Franklin magmatism. The Clarence Head dykes represent a large swarm tangential to, and cogenetic with, a giant radiating dyke swarm ∼800 km from the indicated source. The preferred mechanism for the emplacement of the Clarence Head dykes is the exploitation of concentric zones of extension around a depleting and collapsing plume source. While the paleomagnetism of most Clarence Head dykes agrees with that of the Franklin dykes, two dykes have anomalous remanence directions, interpreted to be a chemical remanent magnetization carried by pyrrhotite. The pyrrhotite was likely deposited from fluids mobilized southward from the Devonian Ellesmerian Orogeny to the north that used the interiors of the dykes as conduits and precipitated pyrrhotite en route.

A 1.78 Ga large igneous province in the North China craton: The Xiong'er Volcanic Province and the North China dyke swarm

Lithos ◽  
2008 ◽  
Vol 101 (3-4) ◽  
pp. 260-280 ◽  
Author(s):  
Peng Peng ◽  
Mingguo Zhai ◽  
Richard E. Ernst ◽  
Jinghui Guo ◽  
Fu Liu ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Large Igneous Province ◽  
Dyke Swarm ◽  
Volcanic Province ◽  
The North ◽  
Igneous Province

Paleomagnetism and U–Pb geochronology of Franklin dykes in High Arctic Canada and Greenland: a revised age and paleomagnetic pole constraining block rotations in the Nares Strait regionThis is a companion paper to Denyszyn, S.W., Davis, D.W., and Halls, H.C. Paleomagnetism and U–Pb geochronology of the Clarence Head dykes, Arctic Canada: orthogonal emplacement of mafic dykes in a large igneous province. Canadian Journal of Earth Sciences, 46(3): 155–167.

2009 ◽  
Vol 46 (9) ◽  
pp. 689-705 ◽  
Author(s):  
Steven W. Denyszyn ◽  
Henry C. Halls ◽  
Don W. Davis ◽  
David A.D. Evans
Keyword(s):  
High Arctic ◽  
Companion Paper ◽  
North American Plate ◽  
Large Igneous Province ◽  
Arctic Canada ◽  
Age Progression ◽  
The North ◽  
Paleomagnetic Poles ◽  
The Difference ◽  
Key Pole

U–Pb baddeleyite ages and paleomagnetic poles obtained for dykes on Devon Island and Ellesmere Island in the Canadian Arctic and the Thule region of Greenland show that they are associated with the Franklin magmatic event. This study is the only one devoted to Franklin igneous rocks where a primary paleomagnetic remanence and U–Pb age have been obtained from the same rocks. Ages from this study range from 721 to 712 Ma, but paleomagnetic directional data show no clear age progression. The paleomagnetic poles from each of the two regional subsets are significantly different at the 95% confidence level from paleomagnetic results previously published for the Franklin event in the Canadian Shield. The difference in the pole locations can be accounted for, to first approximation, by a simple model of early Cenozoic block rotations among the North American plate, Greenland, and a hypothesized ancient microplate comprising Ellesmere, Devon, Cornwallis, and perhaps Somerset islands. A new grand-mean paleopole for the Franklin event, including restoration of Greenland and the proposed “Ellesmere microplate” to North America, is located at (8.4°N, 163.8°E, A95 = 2.8°, N = 78 sites) and is a key pole for Neoproterozoic supercontinent reconstructions.

Borden dykes of Baffin Island, Northwest Territories: a Franklin U-Pb baddeleyite age and a paleomagnetic reinterpretation

1999 ◽  
Vol 36 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Sally J Pehrsson ◽  
Kenneth L Buchan
Keyword(s):  
Northwest Territories ◽  
Remanent Magnetization ◽  
Paleomagnetic Data ◽  
Dyke Swarm ◽  
Baffin Island ◽  
Normal Faulting ◽  
Polar Wander ◽  
Baffin Bay ◽  
The North ◽  
Chemical Remanent Magnetization

U-Pb baddeleyite geochronology for two Borden diabase dykes of northern Baffin Island gives an intrusion age of ca. 720 Ma, coeval with the age established elsewhere for the Franklin igneous event. Thus, the Borden dykes belong to the Franklin dyke swarm, rather than forming a separate swarm that intruded at ca. 950-900 Ma, as has been suggested previously on the basis of paleomagnetism and K-Ar ages. As a result, the paleopole from the Borden dykes can no longer be utilized to help constrain the ca. 1050-850 Ma Grenville Loop of the North American polar wander path. Reevaluation of paleomagnetic data for the dykes of northern Baffin Island suggests that Borden dyke magnetizations resulted from superposition of a steeply directed component of chemical remanent magnetization on normal and reversed primary Franklin components. The overprint direction is consistent with a Cretaceous-Tertiary age and is likely related to normal faulting and graben development during the opening of Baffin Bay.

scholarly journals New constraints on the age, geochemistry, and environmental impact of High Arctic Large Igneous Province magmatism: Tracing the extension of the Alpha Ridge onto Ellesmere Island, Canada

2020 ◽  
Author(s):  
T.V. Naber ◽  
S.E. Grasby ◽  
J.P. Cuthbertson ◽  
N. Rayner ◽  
C. Tegner
Keyword(s):  
Volcanic Rocks ◽  
High Arctic ◽  
Ellesmere Island ◽  
Large Igneous Province ◽  
The Arctic ◽  
Trace Element Geochemistry ◽  
Volcanic Complex ◽  
Northern Coast ◽  
Element Geochemistry ◽  
Igneous Province

The High Arctic Large Igneous Province (HALIP) represents extensive Cretaceous magmatism throughout the circum-Arctic borderlands and within the Arctic Ocean (e.g., the Alpha-Mendeleev Ridge). Recent aeromagnetic data shows anomalies that extend from the Alpha Ridge onto the northern coast of Ellesmere Island, Nunavut, Canada. To test this linkage we present new bulk rock major and trace element geochemistry, and mineral compositions for clinopyroxene, plagioclase, and olivine of basaltic dykes and sheets and rhyolitic lavas for the stratotype section at Hansen Point, which coincides geographically with the magnetic anomaly at northern Ellesmere Island. New U-Pb chronology is also presented. The basaltic and basaltic-andesite dykes and sheets at Hansen Point are all evolved with 5.5−2.5 wt% MgO, 48.3−57.0 wt% SiO2, and have light rare-earth element enriched patterns. They classify as tholeiites and in Th/Yb vs. Nb/Yb space they define a trend extending from the mantle array toward upper continental crust. This trend, also including a rhyolite lava, can be modeled successfully by assimilation and fractional crystallization. The U-Pb data for a dacite sample, that is cut by basaltic dykes at Hansen Point, yields a crystallization age of 95.5 ± 1.0 Ma, and also shows crustal inheritance. The chronology and the geochemistry of the Hansen Point samples are correlative with the basaltic lavas, sills, and dykes of the Strand Fiord Formation on Axel Heiberg Island, Nunavut, Canada. In contrast, a new U-Pb age for an alkaline syenite at Audhild Bay is significantly younger at 79.5 ± 0.5 Ma, and correlative to alkaline basalts and rhyolites from other locations of northern Ellesmere Island (Audhild Bay, Philips Inlet, and Yelverton Bay West; 83−73 Ma). We propose these volcanic occurrences be referred to collectively as the Audhild Bay alkaline suite (ABAS). In this revised nomenclature, the rocks of Hansen Point stratotype and other tholeiitic rocks are ascribed to the Hansen Point tholeiitic suite (HPTS) that was emplaced at 97−93 Ma. We suggest this subdivision into suites replace the collective term Hansen Point volcanic complex. The few dredge samples of alkali basalt available from the top of the Alpha Ridge are akin to ABAS in terms of geochemistry. Our revised dates also suggest that the HPTS and Strand Fiord Formation volcanic rocks may be the hypothesized subaerial large igneous province eruption that drove the Cretaceous Ocean Anoxic Event 2.

Tracking compositional changes within the High Arctic Large Igneous Province using zircon Hf isotopes from altered volcanic ash layers of the Sverdrup Basin, Canada

2021 ◽  
Author(s):  
Michael Pointon ◽  
Michael Flowerdew ◽  
Peter Hülse ◽  
Simon Schneider ◽  
Ian Millar ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Volcanic Ash ◽  
Volcanic Belt ◽  
High Arctic ◽  
Ellesmere Island ◽  
Hf Isotope ◽  
Large Igneous Province ◽  
Volcanic Material ◽  
Igneous Province ◽  
Sverdrup Basin

<p>During Late Cretaceous times the Sverdrup Basin, Arctic Canada, received considerable air-fall volcanic material. This is manifested as numerous centimetre- to decimetre-thick diagenetically altered volcanic ash layers (bentonites) that occur interbedded with mudstones of the Kanguk Formation. Previous research on bentonite samples from an outcrop section in the east of the basin (Sawtooth Range, Ellesmere Island) revealed two distinct volcanic sources for the bentonites: most of the bentonites analysed (n=9) are relatively thick (0.1 to 5 m), were originally alkaline felsic ashes, and were likely sourced from local volcanic centres on northern Ellesmere Island or the Alpha Ridge that were associated with the High Arctic Large Igneous Province (HALIP). Two thinner (<5 cm) bentonites with contrasting subalkaline geochemistry were also identified. These were inferred to have been derived from further afield, from volcanic centres within the Okhotsk-Chukotka Volcanic Belt, Russia.</p><p>To better understand volcanism within the vicinity of the Sverdrup Basin during Late Cretaceous times, and further test the above interpretations, a larger suite of bentonite samples was investigated, drawing on samples from outcrop sections in the central and eastern Sverdrup Basin. Whole-rock geochemical analyses and combined zircon U-Pb age and Hf isotope analyses were undertaken. The vast majority of bentonites analysed to date have alkaline geochemistry and were likely sourced from proximal volcanic centres related to the HALIP. The combined U-Pb and Hf isotope data from these bentonites show a progression from evolved (-2 to 0) to moderately juvenile (+9 to +10) εHf<sub>(t)</sub> values between late Cenomanian and early Campanian times (<em>c</em>. 97–81 Ma). This is interpreted to record compositional change through time within the local HALIP magmatic system.</p>

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