Quantifying Basement Characteristics of the Davis Strait Transform Margin by Geophysical Data Modeling
Abstract
The Davis Strait is underlain by a transform margin that lies between Canada and Greenland and separates the rifted margins of Baffin Bay to the north from the Labrador Sea to the south. This margin is complicated by igneous intrusions, underplating, precursory rifting, strike-slip transform faults, and fracture zones resulting in a complex geologic evolution. Geophysical modeling provides a means to assess this evolution and quantify major features, such as the Davis Strait High, Ungava Fault Complex, Hudson Fracture Zone, and nature of the underlying crust. Available geological and geophysical data are compiled, and a series of data processing and modeling methods are developed to quantify basement features. Sediment thickness is mapped between the seafloor and top of the volcanics or pre-rift basement. Based on sediment compaction theory, we construct a velocity model using wireline sonic logs, check-shot surveys, RMS velocities from seismic reflection data, and refraction models to transform two-way time to depth. We independently estimate the depth to basement from magnetic data using a tilt-angle method and integrate it with seismic sediment thickness. With the bathymetry and calculated depth to basement, we model the basement Bouguer anomaly with a varying density model. Finally, we estimate, map, and classify the ratio of basement density to magnetic susceptibility. Our methods provide the most comprehensive sediment velocity model and sediment thickness map produced along the Canadian side of the Davis Strait. The estimated ratio of basement density to magnetic susceptibility corresponds well with the variations of basement lithology, age, tectonics, and thermodynamic condition inferred from known velocity structure and geologic features, and we are able to extrapolate its 3D distribution throughout the study area. Features such as the Davis Strait High, Ungava Fault Complex, and Hudson Fracture Zone can be reasonably explained from the final mapping.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMNS22A..08L
- Keywords:
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- 0920 Gravity methods;
- EXPLORATION GEOPHYSICSDE: 0925 Magnetic and electrical methods;
- EXPLORATION GEOPHYSICSDE: 0935 Seismic methods;
- EXPLORATION GEOPHYSICSDE: 0999 General or miscellaneous;
- EXPLORATION GEOPHYSICS