Precambrian U–Pb ages of igneous rocks, Wrangel Complex, Wrangel Island, USSR

1991 ◽  
Vol 28 (9) ◽  
pp. 1340-1348 ◽  
Author(s):  
M. P. Cecile ◽  
J. C. Harrison ◽  
M. K. Kos'ko ◽  
R. R. Parrish
Keyword(s):  
Volcanic Rocks ◽  
Canadian Arctic ◽  
Canada Basin ◽  
The Arctic ◽  
Porphyritic Granite ◽  
Late Proterozoic ◽  
Wrangel Island ◽  
Arctic Alaska ◽  
Continuous Plate ◽  
Orogenic Events

Proterozoic rocks exposed in an anticlinorium at the centre of Wrangel Island are among some of the few exposures of Precambrian strata around Canada Basin. U–Pb zircon dating of samples collected during joint Canadian–Soviet fieldwork on the island has provided crystallization ages of [Formula: see text] on a volcanic rock, 699 ± 2 Ma on a porphyritic granite sill, and a very imprecise age of ca. 0.7 Ga on a small leucogranite. Broadly similar 600–750 Ma, mostly metamorphic, ages are known from both the Arctic Alaska and northern Chukotkan parts of what is called the Arctic Alaska – Chukotka Ancestral Plate, supporting the hypothesis that they were once a single entity. By contrast, potential Late Proterozoic equivalents in the Canadian Arctic Islands include a deeply buried and relatively undeformed seismically defined succession of hypothesized Late Proterozoic age, now at greenschist-facies metamorphic grade, and the unmetamorphosed 725 Ma Franklin mafic sills, dykes, and volcanic rocks. The differences in metamorphic and igneous ages between the Arctic Alaska–Chukotka Ancestral Plate and the Canadian Arctic Islands suggest that these two areas have fundamentally different Precambrian rocks. If so, this challenges the fundamental assumption of most paleogeographic models of the pre-Canada Basin Arctic that the two areas once formed a single continuous plate. Earlier K–Ar dates together with major unconformities in Phanerozoic successions on Wrangel Island suggest early Paleozoic orogenic events.

Evolution of sedimentary basins in the Canadian Arctic

1982 ◽  
Vol 305 (1489) ◽  
pp. 193-205 ◽  
Keyword(s):  
Late Cretaceous ◽  
Volcanic Rocks ◽  
Canadian Arctic ◽  
Sedimentary Basins ◽  
Early Carboniferous ◽  
Canada Basin ◽  
The Arctic ◽  
Second Phase ◽  
Southeastern Part ◽  
Sverdrup Basin

Since middle Proterozoic time, two long-lasting phases affected the Canadian Arctic Archipelago, each forming a different sedimentary basin. The Franklinian Basin, which was floored by continental or quasi-continental crust, received 10 km or more of clastic, carbonate and volcanic rocks from the mid-Proterozoic to Devonian. Internal parts of the basin were deformed, intruded and metamorphosed locally, and external parts were folded and thrust cratonward by compressional episodes of the Ellesmerian Orogeny, which culminated in the late Devonian. This marked the end of a phase, at which time the entire region may have been emergent. The nature of plate interactions that produced Ellesmerian deformation are unknown. The second phase began in the early Carboniferous, when plate movements of the Boreal Rifting Episode created the proto-Canada Basin by left-hand transform motion of a plate along the modern continental margin and the location of the Kaltag Fault of northern Alaska. As a marginal side effect of that motion, the Sverdrup Basin developed as a peri-cratonic incipient rift. From the Carboniferous to late Cretaceous the basin received about 13 km of cratonic-derived clastic detritus. From late Cretaceous to early Tertiary time, the Arctic Archipelago was disrupted by the interference of two plate movements originating in the Arctic and North Atlantic regions. Those events had three main effects: the craton was extended and a graben-filled depression formed in the southeastern part of the archipelago; the eastern and central parts of the Sverdrup Basin were compressed and uplifted (Eurekan Orogeny); and resultant elastics prograded northwestward toward the Canada Basin, to form the Arctic continental terrace wedge.

scholarly journals The recent state and variability of the carbonate system of the Canadian Arctic Archipelago and adjacent basins in the context of ocean acidification

2020 ◽  
Vol 17 (14) ◽  
pp. 3923-3942
Author(s):  
Alexis Beaupré-Laperrière ◽  
Alfonso Mucci ◽  
Helmuth Thomas
Keyword(s):  
Ocean Acidification ◽  
Dissolved Inorganic Carbon ◽  
Canadian Arctic ◽  
Canada Basin ◽  
The Arctic ◽  
Canadian Arctic Archipelago ◽  
Potential Threat ◽  
Carbonate System ◽  
System Parameters ◽  
Spatial Coverage

Abstract. Ocean acidification driven by the uptake of anthropogenic CO2 by the surface oceans constitutes a potential threat to the health of marine ecosystems around the globe. The Arctic Ocean is particularly vulnerable to acidification and thus is an ideal region to study the progression and effects of acidification before they become globally widespread. The appearance of undersaturated surface waters with respect to the carbonate mineral aragonite (ΩA<1), an important threshold beyond which the calcification and growth of some marine organisms might be hindered, has recently been documented in the Canada Basin and adjacent Canadian Arctic Archipelago (CAA), a dynamic region with an inherently strong variability in biogeochemical processes. Nonetheless, few of these observations were made in the last 5 years and the spatial coverage in the latter region is poor. We use a dataset of carbonate system parameters measured in the CAA and its adjacent basins (Canada Basin and Baffin Bay) from 2003 to 2016 to describe the recent state of these parameters across the Canadian Arctic and investigate the amplitude and sources of the system's variability over more than a decade. Our findings reveal that, in the summers of 2014 to 2016, the ocean surface across our study area served as a net CO2 sink and was partly undersaturated with respect to aragonite in the Canada Basin and the Queen Maud Gulf, the latter region exhibiting undersaturation over its entire water column at some locations. We estimate, using measurements made across several years, that approximately a third of the interannual variability in surface dissolved inorganic carbon (DIC) concentrations in the CAA results from fluctuations in biological activity. In consideration of the system's variability resulting from these fluctuations, we derive times of emergence of the anthropogenic ocean acidification signal for carbonate system parameters in the study area.

scholarly journals Investigating the Paleozoic–Mesozoic low-temperature thermal history of the southwestern Canadian Arctic: insights from (U–Th)/He thermochronology

2017 ◽  
Vol 54 (4) ◽  
pp. 430-444 ◽  
Author(s):  
D. Midwinter ◽  
J. Powell ◽  
D.A. Schneider ◽  
K. Dewing
Keyword(s):  
Low Temperature ◽  
Vitrinite Reflectance ◽  
Canadian Arctic ◽  
The Arctic ◽  
Late Paleozoic ◽  
Marked Contrast ◽  
Early Mesozoic ◽  
Arctic Alaska ◽  
Thermal Maximum ◽  
History Of

The Arctic Amerasia Basin, located between the Canadian margin and Alaska, formed by purported Jurassic–Cretaceous rifting related to the rotation of the Arctic Alaska – Chukotka microcontinent from northern Laurentia. Rifting may have been accompanied by rift shoulder uplift and cooling that is recorded in low-temperature thermochronometers. Furthermore, the southwestern Canadian Arctic has a widespread Devonian–Cretaceous unconformity with a poorly understood burial-unroofing history. We evaluate new zircon (U–Th)/He thermochronology (ZHe) and organic maturity (vitrinite reflectance (VRo)) data from Neoproterozoic strata of the Amundsen Basin, Cambrian strata of the Arctic Platform, and Devonian strata of the Franklinian Basin to help resolve the sedimentary thickness deposited and eroded during the time represented by the regional unconformity. ZHe and VRo models identify the thermal maximum occurring between the late Paleozoic – Mesozoic interval. Proximal to the rifted Canadian margin, models estimate 3.7–4.5 km of deposition between the Devonian–Cretaceous, in marked contrast to <1 km towards the craton. Jurassic–Cretaceous exhumation is estimated at 2.3–3.5 km and is more uniform across the region. Although the magnitude of burial and erosion can be resolved by modelling, the timing of these events cannot be elucidated with confidence. The thermochronology models can be satisfied by either (1) late Paleozoic – early Mesozoic burial with a thermal maximum prior to Jurassic rifting, followed by cooling; or (2) Late Devonian maximum burial, with gradual unroofing until Cretaceous sedimentation. Although continued deposition into the Mesozoic towards the craton interior seems unlikely, it remains possible that there was continued deposition proximal to the rifted Canadian margin.

Late Proterozoic–Paleozoic evolution of the Arctic Alaska–Chukotka terrane based on U-Pb igneous and detrital zircon ages: Implications for Neoproterozoic paleogeographic reconstructions

2009 ◽  
Vol 121 (9-10) ◽  
pp. 1219-1235 ◽  
Author(s):  
Jeffrey M. Amato ◽  
Jaime Toro ◽  
Elizabeth L. Miller ◽  
George E. Gehrels ◽  
G. Lang Farmer ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
The Arctic ◽  
Late Proterozoic ◽  
Arctic Alaska ◽  
Detrital Zircon Ages

Logistic problems in the Canadian Arctic

Polar Record ◽  
1961 ◽  
Vol 10 (67) ◽  
pp. 365-371
Author(s):  
T. A. Harwood
Keyword(s):  
United States ◽  
Canadian Arctic ◽  
The United States ◽  
The Arctic ◽  
Weather Bureau ◽  
Weather Stations ◽  
Resolute Bay ◽  
States Weather

In 1946 the United States Weather Bureau and the Canadian Meteorological Service installed the first of the Joint Arctic Weather Stations at Resolute Bay. The network of satellite stations was extended into the Arctic archipelago in the following years on roughly a 275-mile spacing to Mould Bay, Isachsen, Eureka and Alert.

scholarly journals Regional variability of acidification in the Arctic: a sea of contrasts

2014 ◽  
Vol 11 (2) ◽  
pp. 293-308 ◽  
Author(s):  
E. E. Popova ◽  
A. Yool ◽  
Y. Aksenov ◽  
A. C. Coward ◽  
T. R. Anderson
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Arctic Ocean ◽  
Canadian Arctic ◽  
Atmospheric Co2 ◽  
The Arctic ◽  
Canadian Arctic Archipelago ◽  
Regional Variability ◽  
The Arctic Ocean ◽  
The Impact

Abstract. The Arctic Ocean is a region that is particularly vulnerable to the impact of ocean acidification driven by rising atmospheric CO2, with potentially negative consequences for calcifying organisms such as coccolithophorids and foraminiferans. In this study, we use an ocean-only general circulation model, with embedded biogeochemistry and a comprehensive description of the ocean carbon cycle, to study the response of pH and saturation states of calcite and aragonite to rising atmospheric pCO2 and changing climate in the Arctic Ocean. Particular attention is paid to the strong regional variability within the Arctic, and, for comparison, simulation results are contrasted with those for the global ocean. Simulations were run to year 2099 using the RCP8.5 (an Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) scenario with the highest concentrations of atmospheric CO2). The separate impacts of the direct increase in atmospheric CO2 and indirect effects via impact of climate change (changing temperature, stratification, primary production and freshwater fluxes) were examined by undertaking two simulations, one with the full system and the other in which atmospheric CO2 was prevented from increasing beyond its preindustrial level (year 1860). Results indicate that the impact of climate change, and spatial heterogeneity thereof, plays a strong role in the declines in pH and carbonate saturation (Ω) seen in the Arctic. The central Arctic, Canadian Arctic Archipelago and Baffin Bay show greatest rates of acidification and Ω decline as a result of melting sea ice. In contrast, areas affected by Atlantic inflow including the Greenland Sea and outer shelves of the Barents, Kara and Laptev seas, had minimal decreases in pH and Ω because diminishing ice cover led to greater vertical mixing and primary production. As a consequence, the projected onset of undersaturation in respect to aragonite is highly variable regionally within the Arctic, occurring during the decade of 2000–2010 in the Siberian shelves and Canadian Arctic Archipelago, but as late as the 2080s in the Barents and Norwegian seas. We conclude that, for future projections of acidification and carbonate saturation state in the Arctic, regional variability is significant and needs to be adequately resolved, with particular emphasis on reliable projections of the rates of retreat of the sea ice, which are a major source of uncertainty.

Claiming Spaces for Science

2017 ◽  
Vol 47 (2) ◽  
pp. 164-199
Author(s):  
Adam M. Sowards
Keyword(s):  
Canadian Arctic ◽  
The Arctic ◽  
Professional Literature ◽  
Popular Discourse ◽  
Scientific Authority ◽  
Competing Demands ◽  
Complicated Process ◽  
History Of ◽  
External Forces ◽  
Reciprocal Process

Exploration has always centered on claims: for country, for commerce, for character. Claims for useful scientific knowledge also grew out of exploration’s varied activities across space and time. The history of the Canadian Arctic Expedition of 1913–18 exposes the complicated process of claim-making. The expedition operated in and made claims on many spaces, both material and rhetorical, or, put differently, in several natural and discursive spaces. In making claims for science, the explorer-scientists navigated competing demands on their commitments and activities from their own predilections and from external forces. Incorporating Arctic spaces into the Canadian polity had become a high priority during the era when the CAE traversed the Arctic. Science through exploration—practices on the ground and especially through scientific and popular discourse—facilitated this integration. So, claiming space was something done on the ground, through professional literature, and within popular narratives—and not always for the same ends. The resulting narrative tensions reveal the messy material, political, and rhetorical spaces where humans do science. This article demonstrates how explorer-scientists claimed material and discursive spaces to establish and solidify their scientific authority. When the CAE claimed its spaces in nature, nation, and narrative, it refracted a reciprocal process whereby the demands of environment, state, and discourse also claimed the CAE.

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