The paper “Impacts of fault-sill interactions on sill emplacement in the Vøring Basin, Norwegian North Sea” by the authors Einstein Siregar, Kamaldeen Omosanya, Craig Magee, and Ståle Johansen, has been accepted with minor corrections in the Journal of Structural Geology.
Pre-existing faults may facilitate subsurface magma transport and sill trangression in sedimentary basins. Although widely recognized, interaction between faults and intrusion networks in sedimentary basins remains poorly imaged by seismic reflection data. To understand how sills interact with pre-existing faults in sedimentary basins, we use high-resolution 3-D seismic reflection data from the Naglfar Dome, Vøring Basin to examine the seismic expression of sills, interpret fault geometries and displacement patterns, and characterize sill-fault interactions. Sills in the area range from 6 km2 to 180 km2 and display saucer-shaped, transgressive, and strata-concordant morphologies. The sills are interconnected and form a sill-complex, emplaced during the post-Early Eocene, spanning three main stratigraphic intervals (i.e. Nise, Tang, and Brygge Formations) from depths of -3000 ms TWTT to -5500 ms TWTT. Faults are tectonic in origin and dominated by normal faults that generally can reach 28 km long in plan-view. Fault and sill interactions are define a spectrum, which we sub-divided into five categories (i.e., Type 1a, 1b, 2, 3 and 4); the two main end-member fault-sill relationships documented here are (a) sills stepping stratigraphy and (b) those with their inclined segments intruded along fault planes. The displacement plots show that sill intrusion into fault planes do not have any influence on fault displacement character. Sill emplacement was along the strike of faults and perpendicular to the least compressive stress. Our work further demonstrates the intricate interaction of fault and magmatic sills and its broader implications for magma plumbing in many magma-rich continental margins.
Keywords: Magma, sills, faults, intersection geometries, emplacement, plumbing, Vøring Basin.
Siregar, E., Omosanya, K.O, Magee, C, Johansen, S.E. (accepted): Impacts of fault-sill interactions on sill emplacement in the Vøring Basin, Norwegian North Sea. Accepted for minor correction in Journal of Structural Geology. [intranet]