Abstract

The geometry and kinematic evolution of oblique convergence zones are poorly understood, especially in the more deeply eroded ductile roots of ancient orogenic belts. As a consequence, evidence for major lateral displacements may remain undetected. In Dronning Louise Land, northeastern Greenland, a major partitioned system of strike-slip and ductile thrust shear zones has formed in response to hitherto unrecognized Caledonian sinistral transpression. This system formed at mid-crustal depths (amphibolite facies), possibly due to oblique collision between Baltica and Laurentia during Ordovician to Early Devonian time. An early phase of low-angle strike slip is superseded by synchronous compressional thrusting and high-angle sinistral displacements. These are partitioned into shear zones arranged in a fashion similar to the fault patterns observed in the hanging walls of modern-day oblique convergent margins. Left-lateral displacements in the eastern Greenland Caledonides are likely to be tens to hundreds of kilometres. A direct correspondence between stretching lineations and Caledonian plate motion vectors is unlikely, although the strike-slip shear zone is probably parallel to the Laurentian paleo-plate margin.

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