Mesozoic faulting in East Greenland

Abstract

Mesozoic faulting in the East Greenland Basin is interpreted as the result of graben formation extending from a postulated "trilete junction" south of Scoresby Sund. Faults appear slightly curved in plan, but can be divided into straight sections 2 - 10 km long (up to 20° between adjacent segments). They are normal types only, dipping 60° - 80°, with throws up to 4 km partly resulting from block rotation. Although this rotation implies faults curved in section, they can usually be assumed flat with such large radii of curvature. Major faults are often complex zones (0.5 - 4 km wide) of narrow blocks and slivers. Faulting was partly synsedimentary. Comparisons of pre-Mesozoic and Mesozoic fault directions show fairly similar dominant trends (335°, 355°, 015° - 025°,035° - 050° & 085° - 090°) in all areas, indicating that pre-existing basement anisotropies controlled directions of Mesozoic-Cenozoic faulting. Basin formation was accomplished by roughly N-S boundary faults in east and west and major NW-SE faults, which together defined a series of fault blocks (subsiding successively from south to north). In Volgian- Valanginian times, the basin was further split into N-S trending antithetic blocks by faults 10 - 30 km apart (crustal extension about 6%).