The Thores volcanic island arc of the Pearya Terrane from Ellesmere Island formed on Precambrian continental crust

2021 ◽  
Author(s):  
Jarosław Majka ◽  
Karolina Kośmińska ◽  
Jakub Bazarnik ◽  
William C. McClelland
Keyword(s):  
Continental Crust ◽  
High Arctic ◽  
Sensu Stricto ◽  
Ellesmere Island ◽  
Island Arc ◽  
Fault System ◽  
Published Data ◽  
Island Arcs ◽  
Volcanic Island ◽  
National Science

<p>We report on U-Pb zircon dating and bulk rock geochemistry results of intermediate to felsic rocks of the Thores Suite of the Pearya Terrane, northern Ellesmere Island (Arctic Canada).  Our new results together with the previously published data show that the Thores Suite was formed in the Early Ordovician (c. 490-470 Ma) as a part of an island arc. Some of the dated samples revealed common xenocrystic zircon. The latter yielded ages ranging between c. 2690 Ma and c. 520 Ma. The obtained ages of xenocrystic zircon are interpreted to be typical of Laurentia. We propose that the youngest obtained cluster of ages c. 580-570 Ma expresses a component typical for the Timanide Orogen, which is conventionally tied to Baltica. The newdataset sheds light on the history and understanding of the Thores Suite, which used to be explained as an effect of the M’Clintock orogenesis. The latter event was commonly presented as foreign to the major Caledonian orogenesis sensu stricto. In our view, the Thores Suite represents an island arc, which was formed on a fragment of continental crust dismembered during Iapetus opening. Importantly, the age of the Thores island arc is coeval with other island arcs and high pressure metamorphic units of the Scandinavian and Svalbard Caledonides. Thus, it is likely that the Thores volcanic island arc was a part of the larger arc system operating within northern Iapetus. The juxtaposition of the Thores arc with the other successions of the Pearya Terrane is ascribed to a major sinistral strike-slip escape fault-system developed along the northeastern margins of Baltica and Laurentia, broadly concurrent with the main Scandian collision between the two aforementioned continents. This crustal scale fault structure enabled the juxtaposition of numerous crustal blocks of different Precambrian ancestry that can be found in various regions of the current High Arctic, including Svalbard, Greenland and Ellesmere Island.</p><p>This research was supported by the National Science Centre (Poland) project no. 2015/17B/ST10/03114 and the internal AGH-UST funding to J. Majka, the internal grant of the Polish Geological Institute - NRI no. 62.9012.2014.00.0 to J. Bazarnik and the National Science Foundation (USA) grant EAR1650022 to J. Gilotti and W. McClelland.</p>

scholarly journals The Ordovician Thores volcanic island arc of the Pearya Terrane from northern Ellesmere Island formed on Precambrian continental crust

Lithos ◽  
2021 ◽  
Vol 386-387 ◽  
pp. 105999
Author(s):  
Jarosław Majka ◽  
Karolina Kośmińska ◽  
Jakub Bazarnik ◽  
William C. McClelland
Keyword(s):  
Continental Crust ◽  
Ellesmere Island ◽  
Island Arc ◽  
Volcanic Island

scholarly journals The role of island-arc oceanic, collisional and intraplate magmatism in the formation of continental crust in the Mongolia-Trasnbaikalia region: geostructural, geochronological and Sm-Nd isotope data

2021 ◽  
Vol 12 (1) ◽  
pp. 1-47
Author(s):  
I. V. Gordienko
Keyword(s):  
Continental Crust ◽  
Early Stage ◽  
Island Arc ◽  
Published Data ◽  
Crustal Material ◽  
Tectonic Structures ◽  
Nd Isotope ◽  
Isotope Data ◽  
Intraplate Magmatism

The formation of continental crust in the Mongolia-Transbaikalia region is researched to identify the mechanisms of interactions between the crust and the mantle in the development of the Neoarchean, Proterozoic and Paleozoic magmatic and sedimentary complexes in the study area. Using the results of his own studies conducted for many years and other published data on this vast region of Central Asia, the author have analysed compositions, ages and conditions for the formation of Karelian, Baikalian, Caledonian and Hercynian structure-formational complexes in a variety of geodynamic settings. Based on the geostructural, petrological, geochemical, geochronological and Sm-Nd isotope data, he determines the crustal and mantle sources of magmatism, conducts the identification and mapping of isotopic provinces, and reveals the role of island-arc oceanic, accretion-collision and intraplate magmatism in the formation of continental crust. Considering the formation of the bulk continental crust, three main stages are distinguished: (1) Neoarchean and Paleoproterozoic (Karelian) (almost 30% of the crust volume), (2) Meso-Neoproterozoic (Baikalian) (50%), and (3) Paleozoic (Caledonian and Hercynian) (over 20%). This sequence of the evolution stages shows the predominance of the ancient crustal material in igneous rocks sources at the early stage. During the subsequent stages, tectonic structures created earlier were repeatedly reworked, and mixed crustal-mantle and juvenile sources were widely involved in the formation of the bulk continental crust in the study area.

Episodic Ordovician-Silurian plutonism in the Topsails igneous terrane, western Newfoundland

1987 ◽  
Vol 78 (1) ◽  
pp. 17-28 ◽  
Author(s):  
J. B. Whalen ◽  
K. L. Currie ◽  
O. van Breemen
Keyword(s):  
Island Arc ◽  
Granitic Rocks ◽  
Island Arcs ◽  
Volcanic Island ◽  
Zircon Age ◽  
Peralkaline Granite ◽  
Early Ordovician ◽  
Intrusive Rocks ◽  
Igneous Activity ◽  
Magmatic History

ABSTRACTThe Topsails igneous terrane of western Newfoundland contains several intrusive and volcanic suites underlain and separated by screens of older intrusive rocks. The heterogeneous Hungry Mountain complex yielded U-Pb zircon upper and lower intercept ages of 2090 ± 75 Ma and 467 ± 8 Ma, demonstrating a significant inherited component of Aphebian age, while an adjacent suite of relatively massive granodioritic to granitic rocks yielded a slightly discordant U-Pb zircon age of 460 ± 10 Ma. The 438 ± 8 Ma age of the Rainy Lake complex, a suite of island arc type intrusive rocks, suggests it forms part of a Silurian magmatic episode, which also included Springdale Group bimodal volcanics (429 ± 4 Ma), and peralkaline granite and subvolcanic porphyries which intrude the Springdale Group (429 ± 3 Ma and 427 ±3 Ma, respectively). Most igneous units contain a slight component of inherited zircon, but initial 87Sr/86Sr ratios (average 0·704) are similar to calculated ‘Bulk Earth’ values at this time.Available data suggest that the Topsails terrane formed an oceanic tract with active volcanic island arcs when obduction commenced in early Ordovician time. The subsequent magmatic history, including the major but short-lived early Silurian magmatism, can be directly or indirectly related to obduction processes, including over-riding of the Topsails terrane by ophiolitic allochthons. There is no evidence of any Acadian (Devonian) igneous activity in the Topsails terrane.

scholarly journals Titanium isotopes as a tracer for the plume or island arc affinity of felsic rocks

2019 ◽  
Vol 116 (4) ◽  
pp. 1132-1135 ◽  
Author(s):  
Zhengbin Deng ◽  
Marc Chaussidon ◽  
Paul Savage ◽  
François Robert ◽  
Raphaël Pik ◽  
...  
Keyword(s):  
Continental Crust ◽  
Plate Tectonics ◽  
Indirect Evidence ◽  
Island Arc ◽  
Island Arcs ◽  
Calc Alkaline ◽  
Magma Differentiation ◽  
Isotopic Signatures ◽  
Crustal Rocks ◽  
Felsic Rocks

Indirect evidence for the presence of a felsic continental crust, such as the elevated 49Ti/47Ti ratios in Archean shales, has been used to argue for ongoing subduction at that time and therefore plate tectonics. However, rocks of intermediate to felsic compositions can be produced in both plume and island arc settings. The fact that Ti behaves differently during magma differentiation in these two geological settings might result in contrasting isotopic signatures. Here, we demonstrate that, at a given SiO2 content, evolved plume rocks (tholeiitic) are more isotopically fractionated in Ti than differentiated island arc rocks (mainly calc-alkaline). We also show that the erosion of crustal rocks from whether plumes (mafic in average) or island arcs (intermediate in average) can all produce sediments having quite constant 49Ti/47Ti ratios being 0.1–0.3 per mille heavier than that of the mantle. This suggests that Ti isotopes are not a direct tracer for the SiO2 contents of crustal rocks. Ti isotopes in crustal sediments are still a potential proxy to identify the geodynamical settings for the formation of the crust but only if combined with additional SiO2 information.

Limnology of high arctic ponds (Cape Herschel, Ellesmere Island, N. W. T.)

1994 ◽  
Vol 131 (4) ◽  
pp. 401-434
Author(s):  
Marianne S. V. Douglas ◽  
John P. Smol
Keyword(s):  
High Arctic ◽  
Ellesmere Island ◽  
Arctic Ponds

An analysis of the stability of thawing slopes, Ellesmere Island, Nunavut, Canada

2000 ◽  
Vol 37 (2) ◽  
pp. 449-462 ◽  
Author(s):  
Charles Harris ◽  
Antoni G Lewkowicz
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Active Layer ◽  
Factor Of Safety ◽  
High Arctic ◽  
Ellesmere Island ◽  
Sensitivity Analyses ◽  
Pore Water Pressures ◽  
Hot Weather ◽  
The Stability

Active-layer detachment slides are locally common on Fosheim Peninsula, Ellesmere Island, where permafrost is continuous, the active layer is 0.5-0.75 m thick, and summer temperatures are unusually high in comparison with much of the Canadian High Arctic. In this paper we report pore-water pressures at the base of the active layer, recorded in situ on two slopes in late July and early August 1995. These data form the basis for slope stability analyses based on effective stress conditions. During fieldwork, the factor of safety within an old detachment slide on a slope at Hot Weather Creek was slightly greater than unity. At "Big Slide Creek," on a slope showing no evidence of earlier detachment failures, the factor of safety was less than unity on a steep basal slope section but greater than unity elsewhere. In the upper slope, pore-water pressures were only just subcritical. Sensitivity analyses demonstrate that the stability of the shallow active layer is strongly influenced by changes in soil shear strength. Possible mechanisms for reduction in shear strength through time include weathering of soils and gradual increases in basal active layer ice content. However, we suggest here that soil shearing during annual gelifluction movements is most likely to progressively reduce shear strengths at the base of the active layer from peak values to close to residual, facilitating the triggering of active-layer detachment failures.Key words: detachment slides, Ellesmere Island, pore-water pressures, gelifluction.

Chrysophycean stomatocysts from the postglacial sediments of a High Arctic lake

1988 ◽  
Vol 66 (6) ◽  
pp. 1117-1128 ◽  
Author(s):  
Katharine E. Duff ◽  
John P. Smol
Keyword(s):  
Species Composition ◽  
Light Microscopy ◽  
High Arctic ◽  
Ellesmere Island ◽  
Arctic Lakes ◽  
Ecological Research ◽  
Stratigraphic Analysis ◽  
Morphological Detail ◽  
Electron And Light Microscopy ◽  
Scanning Electron

Twenty-six chrysophycean stomatocyst morphotypes were described from the postglacial sediments of a small, rock basin lake near Baird Inlet, Ellesmere Island. Scanning electron and light microscopy were used to classify the stomatocysts, following the guidelines of the International Statospore Working Group. None of the stomatocysts could be related with certainty to the chrysophyte species that produced them, but sufficient morphological detail is present in most of the stomatocysts to allow for taxonomic differentiation. A stratigraphic analysis of the dominant stomatocyst morphotypes revealed that chrysophyte species composition changed most markedly during the lake's early development but then remained relatively constant. This study demonstrated that chrysophycean stomatocysts provide useful paleoecological information in High Arctic lakes, but further taxonomic and ecological research is required to fully exploit these microfossils.

Rotifers from five high arctic ponds (Cape Herschel, Ellesmere Island, N.W.T.)

Hydrobiologia ◽  
1989 ◽  
Vol 173 (3) ◽  
pp. 231-242 ◽  
Author(s):  
Thomas Nogrady ◽  
John P. Smol
Keyword(s):  
High Arctic ◽  
Ellesmere Island ◽  
Arctic Ponds
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