In:
Mineralogical Magazine, Mineralogical Society, Vol. 52, No. 366 ( 1988-06), p. 293-307
Abstract:
The Permian magmatic province of the Oslo rift, south-east Norway, includes large volumes of felsic and silicic rocks. Based on their geochemical character, these rocks may be divided into two main groups. The Larvik larvikites (monzonites) are highly enriched in large ion lithophile elements (LILE) (e.g. 10–32 ppm Th. 8–15 ppm Ta), and have an initial 87 Sr/ 86 Sr of 0.70391 ± 5. The syenites and granites have moderate to high concentrations of LILE (e.g. 7–88 ppm Th, 4–25 ppm Ta), and initial 87 Sr/ 86 Sr ratios between 0.705 and 0.707. The Larvik larvikites and extrusive equivalents (rhomb porphyry lavas) have similar initial Sr isotope ratios to uncontaminated basalts and gabbros in the rift, and are believed to have a mantle origin. The higher initial 87 Sr/ 86 Sr ratios in the silicic than in the felsic rocks reflect a crustal component representing the intermediate or low crust. After intrusion into the upper crust, the major and traceelement concentrations of the silicic magmas were modified through fractional crystallization dominated by removal of alkali feldspar, and transport of elements with a fluid phase. The silicic magmas appear not to have interacted significantly with the side rock at this stage.
Type of Medium:
Online Resource
ISSN:
0026-461X
,
1471-8022
DOI:
10.1180/minmag.1988.052.366.01
Language:
English
Publisher:
Mineralogical Society
Publication Date:
1988
detail.hit.zdb_id:
2034522-7
SSG:
13
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