ISSN:
1432-0967
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract The South Rogaland Complex (South Western Norway) consists of several anorthositic intrusions emplaced in granulite facies metamorphic rocks. The anorthosites and related norites and jotunites have δ 18O values of 5.2 to 7‰ suggesting a mantle origin for these rocks, in agreement with the strontium isotopic evidence. The acidic rocks, mostly charnockitic, associated with the anorthosites have similar δ 18O values and thus a comagmatic relation between these two rock types is inferred. Small departures from mantle values are explained in terms of crustal contamination by surrounding gneisses that have δ 18O values between 4.3 and 10‰ Locally, this corresponds to important anatexis as has been suggested for the Farsund charnockite on the basis of strontium isotope and REE geochemistry. The isotopic temperatures calculated from the isotopic fractionations are in the range 500°–700° C, lower than the orthomagmatic temperatures and probably due to subsolidus isotopic exchange during the slow cooling of these plutonic rocks, either during a late magmatic deuteric stage or during a slow, postorogenic ascent under wet conditions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00376150
