NORTH-ATLANTIC VOLCANIC MARGINS - DIMENSIONS AND PRODUCTION-RATES

Authors
Citation
O. Eldholm et K. Grue, NORTH-ATLANTIC VOLCANIC MARGINS - DIMENSIONS AND PRODUCTION-RATES, J GEO R-SOL, 99(B2), 1994, pp. 2955-2968
Citations number
99
Categorie Soggetti
Geosciences, Interdisciplinary
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
ISSN journal
21699313 → ACNP
Volume
99
Issue
B2
Year of publication
1994
Pages
2955 - 2968
Database
ISI
SICI code
2169-9313(1994)99:B2<2955:NVM-DA>2.0.ZU;2-Z
Abstract
Early Tertiary lithospheric breakup between Eurasia and Greenland was accompanied by a transient (approximately 3 m.y.) igneous event emplac ing both the onshore flood basalts of the North Atlantic Volcanic Prov ince (NAVP) and huge extrusive complexes along the continent-ocean tra nsition on the rifted continental margins. Seismic data show that volc anic margins extend >2600 km along the early Eocene plate boundary, in places underlain by high-velocity (7.2-7.7 km/s) lower crustal bodies . Quantitative calculations of NAVP dimensions, considered minimum est imates, reveal an areal extent of 1.3 x 10(6) km2 and a volume of floo d basalts of 1.8 x 10(6) km3, yielding a mean eruption rate of 0.6 km3 /yr or 2.4 km3/yr if two-thirds of the basalts were emplaced with 0.5 m.y. The total crustal volume is 6.6 x 10(6) km3, resulting in a mean crustal accretion rate of 2.2 km3/yr. Thus NAVP ranks among the world' s larger igneous provinces if the volcanic margins are considered. The velocity structure of the expanded crust seaward of the continent-oce an boundary differs from standard oceanic and continental crustal mode ls. Based on seismic velocities this ''volcanic margin'' crust can be divided into three units of which the upper unit corresponds to basalt ic extrusives. The regionally consistent velocity structure and geomet ry of the crustal units suggest that the expanded crust, including the high-velocity lower crust which extends some distance landward of the continent-ocean boundary, was emplaced during and subsequent to break up. The volcanic margin crust was formed by excess melting within a wi de zone of asthenospheric upwelling, probably reflecting the interacti on of a mantle plume and a lithosphere already extending.