Crustal velocity structure of the Southern Nechako Basin, British Columbia, from wide-angle seismic traveltime inversion
| dc.contributor.author | Stephenson, Andrew | |
| dc.contributor.supervisor | Spence, George D. | |
| dc.date.accessioned | 2010-11-30T23:41:46Z | |
| dc.date.available | 2010-11-30T23:41:46Z | |
| dc.date.copyright | 2010 | en |
| dc.date.issued | 2010-11-30T23:41:46Z | |
| dc.degree.department | School of Earth and Ocean Sciences | |
| dc.degree.level | Master of Science M.Sc. | en |
| dc.description.abstract | In the BATHOLITHSonland seismic project, a refraction - wide-angle reflection survey was shot in 2009 across the Coast Mountains and Interior Plateau of central British Columbia. Part of the seismic profile crossed the Nechako Basin, a Jurassic-Cretaceous basin with potential for hydrocarbons within sedimentary rocks that underlie widespread volcanics. Along this 205-km-long line segment, eight explosive shots averaging 750 kg were fired and recorded on 980 seismometers. Forward and inverse modelling of the traveltime data were conducted with two independent methods: ray-tracing based modelling of first and secondary arrivals, and a higher resolution wavefront-based first-arrival seismic tomography. Gravity modelling was utilized as a means of evaluating the density structure corresponding to the final velocity model. Material with velocities less than 5.0 km/s is interpreted as sedimentary rocks of the Nechako Basin, while velocities from 5.0-6.0 km/s may correspond to interlayered sediments and volcanics. The greatest thickness of sedimentary rocks in the basin is found in the central 110 km of the profile. Two sub-basins were identified in this region, with widths of 20-50 km and maximum sedimentary depths of 2.5 km and 3.3 km. Such features are well-defined in the velocity model, since resolution tests indicate that features with widths greater than ~13 km are reliable. Beneath the sedimentary rocks, seismic velocities increase more slowly with depth – from 6.0 km/s just below the basin to 6.3 km/s at ~17 km depth, and then to 6.8-7.0 km/s at the base of the crust. The Moho is interpreted at a depth of 33.5-35 km along the profile, and mantle velocities are high at 8.05-8.10 km/s. | en |
| dc.identifier.uri | http://hdl.handle.net/1828/3145 | |
| dc.language | English | eng |
| dc.language.iso | en | en |
| dc.rights | Available to the World Wide Web | en |
| dc.subject | refraction | en |
| dc.subject | tomography | en |
| dc.subject | tomographic | en |
| dc.subject | BATHOLITHS | en |
| dc.subject | velocity model | en |
| dc.subject | crustal structure | en |
| dc.subject | sedimentary basin | en |
| dc.subject | geology | en |
| dc.subject | gravity model | en |
| dc.subject | ray tracing | en |
| dc.subject.lcsh | UVic Subject Index::Sciences and Engineering::Earth and Ocean Sciences::Geophysics | en |
| dc.title | Crustal velocity structure of the Southern Nechako Basin, British Columbia, from wide-angle seismic traveltime inversion | en |
| dc.type | Thesis | en |