The crustal tongue melting model and the origin of massive anorthosites

Publication Status is "Submitted" Or "In Press: 
LDEO Publication: 
Publication Type: 
Year of Publication: 
1999
Editor: 
Journal Title: 
Terra Nova
Journal Date: 
Apr-Jun
Place Published: 
Tertiary Title: 
Volume: 
11
Issue: 
2-3
Pages: 
100-105
Section / Start page: 
Publisher: 
ISBN Number: 
0954-4879
ISSN Number: 
Edition: 
Short Title: 
Accession Number: 
ISI:000084692200008
LDEO Publication Number: 
Call Number: 
Abstract: 

Recent detailed field studies in several anorthosite complexes have shown that anorthosites are frequently associated with weakness zones in the crust which may have favoured their emplacement at mid-crust levels. Recent experimental data have shown that the parent magma compositions of various anorthosite massifs lie on thermal highs in the relevant phase diagrams at 10-13 kbar, indicating that these magmas cannot be derived by fractionation of peridotitic mantle melts but by melting of gabbronoritic sources in the lower crust at 40-50 km depths. In the Sveconorwegian Province terrane boundaries have been traced in deep seismic profiles to Moho offsets or to tongues of lower crustal material underthrust to depths higher than 40 km. In Southern Norway, we suggest that a lithospheric-scale weakness zone (the Feda transition zone?) has channelled the Rogaland anorthosites through linear delamination, asthenospheric uprise and melting of a mafic lower crustal tongue.

Notes: 

273DKTimes Cited:49Cited References Count:36

DOI: