Geophysical investigation of the Honningsvag igneous complex, Scandinavian Caledonides

T. H. Torsvik, O. Olesen, A. Trench, T. B. Andersen, H. J. Walderhaug, M. A. Smethurst

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The Honningsvag igneous complex within the Mageroy nappe has marked magnetic and gravimetric signatures. Palaeomagnetic studies reveal a Siluro-Devonian (Scandian) dual-polarity remanence. Rock-magnetic and petrological studies indicate a pure magnetite host for the remanent magnetisation component. Magnetic-fabric ellipsoids delineate D1 and D2 Scandian structures affecting the area, and demonstrate an internal reclined fold-structure of the Honningsvag igneous complex. Palaeomagnetic remanence acquisition post-dates emplacement of the Mageroy nappe (late D1), and probably originated during post-D1 uplift. Brittle, upper-crust, D2 deformation which continued into Devonian times, folded the Honningsvag igneous complex and introduced a small but systematic dispersion in the palaeomagnetic remanence directions. Palaeomagnetic and isotopic evidence suggests a syn-tectonic magnetization age of c410 Ma. The palaeomagnetic pole (N47° and E344°) resembles that from the underlying Kalak nappe complex. It is therefore inferred that the Scandian emplacement of the Mageroy nappe was synchronous with a thermal event which affected the older and underlying Finnmarkian-deformed Kalak nappe complex. -from Authors

Original languageEnglish
Pages (from-to)373-381
Number of pages9
JournalJournal - Geological Society (London)
Volume149
Issue number3
DOIs
Publication statusPublished - 1992
Externally publishedYes

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