Exhumation of high-pressure rocks beneath the Solund Basin, Western Gneiss Region of Norway

B. R. Hacker; T.B. Andersen; D.B. Root; L. Mehl; J.M. Mattinson; J. L. Wooden

doi:10.1046/j.1525-1314.2003.00468.x

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Exhumation of high-pressure rocks beneath the Solund Basin, Western Gneiss Region of Norway

B. R. Hacker·T.B. Andersen·D.B. Root·L. Mehl·J.M. Mattinson·J. L. Wooden

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Abstract

The Solund-Hyllestad-Lavik area affords an excellent opportunity to understand the ultrahigh-pressure Scandian orogeny because it contains a near-complete record of ophiolite emplacement, high-pressure metamorphism and large-scale extension. In this area, the Upper Allochthon was intruded by the c. 434 Ma Sogneskollen granodiorite and thrust eastward over the Middle/Lower Allochthon, probably in the Wenlockian. The Middle/Lower Allochthon was subducted to c. 50 km depth and the structurally lower Western Gneiss Complex was subducted to eclogite facies conditions at c. 80 km depth by c. 410-400 Ma. Within < 5-10 Myr, all these units were exhumed by the Nordfjord-Sogn detachment zone, producing shear strains > 100. Exhumation to upper crustal levels was complete by c. 403 Ma. The Solund fault produced the last few km of tectonic exhumation, bringing the near-ultrahigh-pressure rocks to within c. 3 km vertical distance from the low-grade Solund Conglomerate.

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B. R. Hacker, T.B. Andersen, D.B. Root, L. Mehl, J.M. Mattinson, J. L. Wooden. 2003-07-29. Exhumation of high-pressure rocks beneath the Solund Basin, Western Gneiss Region of Norway. https://doi.org/10.1046/j.1525-1314.2003.00468.x

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