Article
 

⁴⁰Ar/³⁹Ar geochronology of silicic and basic volcanic rocks on the margins of the North Atlantic

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/articles/jh343z364

Descriptions

Attribute NameValues
Creator
Abstract
  • At the submerged margins of the North Atlantic, andesitic to dacitic and basaltic volcanic rocks occur together. The silicic rocks were derived by processes requiring the presence of continental crust (crustal anatexis and/or contamination of mafic magmas) while the majority of the basaltic lavas had little or no contact with continental crust. We report ⁴⁰Ar–³⁹Ar incremental heating ages for several dacitic and basaltic rocks recovered from three offshore localities of the North Atlantic Igneous Province. Dacitic lavas and tuffs at the southeast Greenland margin and trachytic lavas in the Scottish Hebrides erupted contemporaneously with basaltic lavas at 62–61 Ma. In contrast, the silicic lavas from the northern Rockall Trough (offshore western Scotland) and the Vøring Plateau (offshore Norway) erupted at ~ 55 Ma followed shortly by basaltic volcanism. At this time, silicic magmatism at the southeast Greenland margin had ceased and only oceanic basalts were erupted. Similarly, ~ 55 Ma lavas on the southwest Rockall Plateau are wholly basaltic. The compositions of all of the dated silicic volcanic rocks are consistent with derivation from partial melting of either continental crust or sediments. The heat necessary for partial melting appears to have been provided by basaltic magmas. Therefore, the existence of the silicic rocks indicates the presence of continental crust as well as a stable tectonic environment that allowed the stagnation and pooling of basaltic melts within the crust. With this in mind, it is apparent that at 62–60 Ma, both western and eastern sides of the present North Atlantic margins were characterized by extensional environments within continental crust that were restrictive to the passage of mafic magmas. By 55 Ma, at the time of continental breakup, the proximal margins at southeast Greenland and the Rockall Plateau were devoid of continental crust. But the presence of 55 Ma silicic magmatism on the eastern North Atlantic margin can be attributed to a broader zone of magmatism and sediment-filled Mesozoic rift basins.
Resource Type
DOI
Date Available
Date Issued
Citation
  • Duncan, R. A., Hitchen, K., and Sinton, C. W. (1998), ⁴⁰Ar/³⁹Ar geochronology of silicic and basic volcanic rocks on the margins of the North Atlantic. Geol. Mag., 135 (2), 161-170.
Journal Title
Journal Volume
  • 135
Journal Issue/Number
  • 2
Academic Affiliation
Rights Statement
Publisher
Language
Replaces

Relationships

Parents:

This work has no parents.

Items

Thumbnail Title Date Uploaded Visibility Actions
file details Sinton_et_al_Geological_Magazine_1998.pdf 2017-12-06 Public Download