40Ar/39Ar geochronology of the West Greenland Tertiary volcanic province

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doi: 10.1016/S0012-821X(98)00112-5
Authors:Storey, M.; Duncan, R. A.; Pedersen, A. K.; Larsen, L. M.; Larsen, H. C.
Author Affiliations:Primary:
Danish Lithosphere Centre, Copenhagen, Denmark
Other:
Oregon State University, United States
Volume Title:Earth and Planetary Science Letters
Source:Earth and Planetary Science Letters, 160(3-4), p.569-586. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X
Publication Date:1998
Note:In English. Includes an appendix. 77 refs.; illus., incl. strat. col., 4 tables, geol. sketch map
Summary:Paleocene volcanic rocks in West Greenland and Baffin Island were among the first products of the Iceland mantle plume, forming part of a larger igneous province that is now submerged beneath the northern Labrador Sea. A 40Ar/39Ar dating study shows that volcanism commenced in West Greenland between 60.9 and 61.3 Ma and that ∼80% of the Paleocene lava pile was erupted in 1 million years or less (weighted mean age of 60.5±0.4 Ma). Minimum estimates of magma production rates (1.3×10-4 km3 year-1 km-1) are similar to the present Iceland rift, except for the uppermost part of the Paleocene volcanic succession where the rate decreases to <0.7×10-4 km3 year-1 km-1 (rift). The timing of onset of volcanism in West Greenland coincides with the opening of the northern Labrador Sea and is also strikingly similar to the age of the oldest Tertiary volcanic rocks from offshore SE Greenland and the British-Irish province. This is interpreted as manifesting the impact and rapid (>1 m/year) lateral spreading of the Iceland plume head at the base of the Greenland lithosphere at ∼62 Ma. We suggest that the arrival, or at least a major increase in the flux, of the Iceland mantle plume beneath Greenland was a contributing factor in the initiation of seafloor spreading in the northern Labrador Sea. Our study has also revealed a previously unrecognised Early Eocene volcanic episode in West Greenland. This magmatism may be related to movement on the transform Ungava Fault System which transferred drifting from the Labrador Sea to Baffin Bay. A regional change in plate kinematics at ∼55 Ma, associated with the opening of the North Atlantic, would have caused net extension along parts of this fault. This would have resulted in decompression and partial melting of the underlying asthenosphere. The source of the melts for the Eocene magmatism may have been remnants of still anomalously hot Iceland plume mantle which were left stranded beneath the West Greenland lithosphere in the Early Paleocene. Abstract Copyright (1998) Elsevier, B.V.
Sections:Age determination
Subjects:Absolute age; Ar/Ar; Basalts; Cenozoic; Crust; Dates; Eocene; Flood basalts; Iceland Plume; Igneous rocks; Lava; Lithosphere; Lower Eocene; Magmatism; Mantle plumes; Paleocene; Paleogene; Plate tectonics; Sea-floor spreading; Tertiary; Volcanic belts; Volcanic rocks; Volcanism; Arctic region; Atlantic Ocean; Disko Island; Greenland; Labrador Sea; North Atlantic; West Greenland; Nuussuaq Greenland
Coordinates:N693000 N705000 W0520000 W0544500
Abstract Numbers:99M/1149
Record ID:1998070452
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
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