INTERLINKED SYSTEM OF DUCTILE STRIKE SLIP AND THRUSTING FORMED BY CALEDONIAN SINISTRAL TRANSPRESSION IN NORTHEASTERN GREENLAND

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 An early phase of low-angle strike slip is superseded by synchronous compressional thrusting and high-angle sinistral displacements.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.