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Rates of volcanic deposition, facies changes and movements in a dynamic basin: the Nuussuaq Basin, West Greenland, around the C27n-C26r transition

By
Asger K. Pedersen
Asger K. Pedersen
Geological Museum, Øster Voldgade 5–7, DK-1350 Copenhagen K, DenmarkDanish Lithosphere Centre, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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Lotte M. Larsen
Lotte M. Larsen
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, DenmarkDanish Lithosphere Centre, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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Peter Riisager
Peter Riisager
Danish Lithosphere Centre, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
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Keld S. Dueholm
Keld S. Dueholm
Informatics and Mathematical Modelling, Technical University of Denmark, Landmålervej 7, DK-2800 Lyngby, Denmark
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Published:
January 01, 2002

Abstract

The initial stages of Palaeogene volcanism in the Nuussuaq Basin in West Greenland were characterized by eruption of basaltic and picritic magmas through sediments of Cretaceous to early Paleocene age into a marine or lowlying coastal environment. Recent magnetostratigraphic work has recognized the C27n-C26r transition (estimated duration less than 10 ka and here assumed to be 5 ka) as a c. 170 m thick zone within a succession of thin picritic lava flows. Multimodel photogrammetry combined with chemical and lithological analysis of the volcanic rocks has allowed detailed 3D analysis of the facies variation within this narrow time window. Subaerial lavas flowed eastwards over a more than 40 km wide front. On northern Disko they covered an existing lava plateau and buried a subaerial landscape of dipping Cretaceous sandstones, while on Nuussuaq they flowed into an up to 700 m deep marine embayment and formed prograding hyaloclastite fans passing into fine-clastic mass flows. With a progradation rate of 0.5–1 m a−1 the palaeogeography of the basin changed considerably during the short time interval. In addition to substantial basin subsidence, the volcanic facies changes have also preserved a record of synvolcanic differential movement of extensional fault blocks. The following parameters are estimated for the volcanism within the Nuussuaq Basin during the C27n-C26r transition: Production rate c. 0.042 km3 a−1, productivity c. 1.2 × 10−3 km3 a−1 km−1 (rift), volcanic aggradation c. 33 m ka−1, subsidence c. 25 m ka−1. If the volcanism evolved continuously at this high aggradation rate, all of the Vaigat Formation could have erupted in 70 ka. However, the complex geological record indicates a much longer total duration, and the volcanism must have had an intermittent character.

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Contents

Geological Society, London, Special Publications

The North Atlantic Igneous Province: Stratigraphy, Tectonic, Volcanic and Magmatic Processes

D. W. Jolley
D. W. Jolley
University of Sheffield, UK
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B. R. Bell
B. R. Bell
University of Glasgow, UK
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Geological Society of London
Volume
197
ISBN electronic:
9781862394452
Publication date:
January 01, 2002

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