Seismic interpretation of sill complexes in sedimentary basins: implications for the sub-sill imaging problem

Christian Haug Eide (Corresponding Author), Nick Schofield, Isabelle Lecomte, Simon J. Buckley, John A Howell

Research output: Contribution to journalArticle

20 Citations (Scopus)
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Abstract

Application of 3D-seismic reflection-data to igneous systems in sedimentary basins has led to a revolution in the understanding of mafic sill complexes. However, there is considerable uncertainty on how geometries and architecture of sill-complexes within the subsurface relates to those imaged in seismic reflection-data. To provide constraints on how sill complexes in seismic data should be interpreted, we present synthetic seismograms generated from a seismic-scale (22x0.25 km) outcrop in East Greenland constrained by
abundant field-data. This study highlights how overlying igneous rocks adversely affect imaging of underlying intrusions and rocks by decreasing seismic amplitude, frequency and making steeply dipping features near-impossible to image. Furthermore, seismic modelling in this study shows that, because of the high impedance contrast between siliciclastic host-rock
and dolerites, very thin (1-5 m) intrusions should in principle be imaged in reflection-seismic data at 3 km depth. However, comparison with actual seismic data with well-data shows significant amounts of unimaged sill intrusions, and this is likely due to limited seismic resolution, overburden complexity, inadequate velocity-models, and interference between reflections from closely spaced sills and sill-splays. Significant improvements to sill imaging and interpretation could be made by better predicting occurrence and geometry of sill intrusions and including these in velocity models.
Original languageEnglish
Pages (from-to)193-209
Number of pages17
JournalJournal of the Geological Society
Volume175
Issue number2
Early online date1 Dec 2017
DOIs
Publication statusPublished - Mar 2018

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