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Samples from the Lomonosov Ridge place new constraints on the geological evolution of the Arctic Ocean

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C. Knudsen
C. Knudsen
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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J. R. Hopper
J. R. Hopper
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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P. R. Bierman
P. R. Bierman
Department of Geology and School of Natural Resources, University of Vermont, Burlington, VT 05405-0122, USA
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M. Bjerager
M. Bjerager
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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T. Funck
T. Funck
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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P. F. Green
P. F. Green
Geotrack International Pty Ltd, 37 Melville Road, Brunswick West, Victoria 3055, Australia
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J. R. Ineson
J. R. Ineson
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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P. Japsen
P. Japsen
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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C. Marcussen
C. Marcussen
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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S. C. Sherlock
S. C. Sherlock
The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
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T. B. Thomsen
T. B. Thomsen
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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Published:
January 01, 2018

Abstract

A number of rock samples were collected from two dredge positions on the Lomonosov Ridge at water depths of 2–3.5 km. The dredge samples are dominated by sediments deformed and metamorphosed under greenschist-facies conditions 470 myr ago according to 40Ar/39Ar dating of metamorphic muscovite. This shows that the Lomonosov Ridge was involved in a major Mid-Ordovician orogenic event that correlates with early arc–terrane accretion observed in northern Ellesmere Island, Svalbard, and other parts of the Caledonian belt. Detrital zircon age spectra of these metasediments span the Mesoproterozoic–Palaeoproterozoic with a main peak at around 1.6 Ga, and a pattern similar to that known from Caledonian metasedimentary rocks in East Greenland and northern Norway, as well as from Cambrian sediments in Estonia and Palaeozoic sediments on Novaya Zemlya. A second population of dredge samples comprises undeformed, non-metamorphic sandstones and siltstones. Detrital zircons in these sediments span the Palaeoproterozoic with a few Archaean zircons. Both rock types are covered by an up to 8 Ma ferromanganese crust and are evaluated to represent outcrop, and apatite fission-track data from three of the rock samples indicate that exposure at the seabed corresponds to a regional event of uplift and erosion that affected the Arctic in the Late Miocene. The data from the Lomonosov Ridge suggest that the 470 Ma orogenic event extended from Scotland and northern Scandinavia into the Arctic, including Svalbard, the Pearya Terrane and the Chukchi Borderlands.

Supplementary material: Detrital zircon age data and details of the thermal history constraints are available at: https://doi.org/10.6084/m9.figshare.c.3852151

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Contents

Geological Society, London, Special Publications

Circum-Arctic Lithosphere Evolution

V. Pease
V. Pease
Stockholm University, Sweden
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B. Coakley
B. Coakley
University of Alaska, Fairbanks, USA
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The Geological Society of London
Volume
460
ISBN electronic:
9781786203410
Publication date:
January 01, 2018

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