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Evidence for a fossil transform fault in the Solund‐Stavfjord Ophiolite Complex: West Norwegian Caledonides
Author(s) -
Skjerlie K. P.,
Furnes H.
Publication year - 1990
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/tc009i006p01631
Subject(s) - geology , dike , mafic , ophiolite , geochemistry , ultramafic rock , transform fault , dalradian , petrology , seismology , metamorphism , fault (geology) , tectonics
On the island of Tviberg, West Norway, a sheeted dike complex is rotated anticlockwise into parallelism with a zone of strong deformation hosting screens of sheared meta‐ultramafite. Incompatible element‐enriched high‐level plutonic rocks and two swarms of mafic dikes are intruded into sheared and unsheared meta‐ultramafites. Intrusion and sinistral shearing of the high‐level plutonic rocks and an old swarm of mafic dikes took place contemporaneously with sinistral shearing of the meta‐ultrabasites. These field relationships are interpreted to reflect magmatism within a transform fault, and the dike rotation is explained as fault drag along a strike‐slip zone in the transform. A younger swarm of mafic dikes, striking at a high angle to the shear zones, transects all tectonic structures and may reflect a second phase of magmatism within the transform. In fault contact with the transform fault related plutonic rocks and dikes, lenses of serpentine diatreme breccias and lenses of sediments composed of mafic and ultramafic detritus are hosted in a phyllonitic matrix comprising basic, ultrabasic and continent‐derived detritus. This rock unit is interpreted as an ophiolitic mélange, and it probably started to form when obduction of the ophiolite nucleated on the transform.