Skip Navigation

This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Markl, G.
Right arrow Articles by Frost, R. B.
Right arrow Search for Related Content
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Journal of Petrology | Volume 40 | Number 1 | Pages 61-77 | 1999
© Oxford University Press 1999

The Origin of Anorthosites and Related Rocks from the Lofoten Islands, Northern Norway: II. Calculation of Parental Liquid Compositions for Anorthosites

Gregor Markl1,* and Ronald B. Frost2

1 Institut Für Mineralogie, Petrologie Und Geochemie, Albert-Ludwigs-Universität Albertstrasse 23 B, D-79104 Freiburg, GERMANY
2 Department of Geology and Geophysics, University of Wyoming Laramie, Wy 82071, USA

Received February 10, 1997; Revised typescript accepted May 14, 1998


  Abstract

Clinopyroxene, orthopyroxene and plagioclase in the Proterozoic Lofoten anorthosites are inferred to be in equilibrium with ferrodioritic melts, on the basis of literature partition coefficients for these phases in equilibrium with basaltic melts. Ferrodiorites and high-Al gabbros occur as fine-grained dykes in spatial association with the ~1.8 Ga Lofoten anorthosites. They are linked to each other by an Fe-enrichment fractionation trend typical of tholeiites, and they are characterized by Al2O3 contents of 14–18.5 wt % and XFe [= FeOtot/(FeOtot + MgO)] between 0.5 and 0.8. The association of high-Al gabbros, ferrodiorites and anorthosites is common in many Proterozoic anorthosites. We infer that the high-Al gabbros to ferrodiorites represent the parental liquids from which these Proterozoic anorthosites formed. The Lofoten rocks show fractionation trends that are similar to those of high-Al gabbros and ferrodiorites from other Proterozoic anorthosite complexes. We interpret these trends in terms of incorporation of intermediate composition plagioclase into a typical tholeiitic magma with subsequent fractionation. The first process produces positive Eu anomalies and the high Al2O3 contents of the melts, and explains the lack of negative Eu anomalies in most of the ferrodiorites from Lofoten and Laramie.

KEY WORDS: anorthosite; parental liquid; ferrodiorite; high-Al basalt; partition coefficients

* Corresponding author. Telephone: xx 49 761 203 6414. Fax: 49 761 203 6407. e-mail: markl{at}ruf.uni-freiburg.de


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.