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The history of the Canada Basin is poorly understood due to its isolation by distance and ice. The best available evidence suggests the Canada Basin formed during a 66˚ counterclockwise rotation of Northern Alaska away from the Canadian Arctic Islands during the Mesozoic. Gravity and magnetic anomaly data show a linear feature that has been interpreted as an extinct Mid Ocean Ridge, buried under thick turbidites and other sediments. For this study we collected MCS data to constrain the Canada Basin sedimentation history and crustal structure and improve our understanding of the basin. During the summer of 2021, we collected ~4514 km of multichannel-seismic reflection (MCS) data complemented by sonobuoy and OBS data across Canada Basin, Arctic Ocean. The MCS data were acquired with two 520 cu inch GI air guns and a 200 meter (32 channels) streamer. The MCS data was processed by eliminating bad traces, applying a bandpass filter, an FK filter to minimize coherent noise, an FX filter to reduce random noise. The filtered traces were then corrected for normal moveout. This utilized a velocity model from this study area. We then stacked to strengthen the signal and applied post-stack migration to relocate the reflection signal for the effect of dipping reflectors. The seismic profiles close to the Northwind Ridge in the west show a relatively flat basement, with thinner sediments compared to the seismic profile over the inferred mid-oceanic ridge. The seismic profiles crossing the mid-oceanic ridge show a high relief central valley. The basement parallel to the inferred ridge axis is smooth, suggesting the ridge is unsegmented, which is consistent with an ultra-slow spreading mid-oceanic ridge. Origin as an ultra-slow spreading ridge constrains the history of the basin, for example indicating the magnetic striped section of the seafloor, that has been interpreted as oceanic crust, based on sonobuoy refractions results, required 15 - 30 Ma to form.
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Seismic Imaging across the Northern Chukchi Borderland: Implications of the Canada Basin Opening
Multichannel-seismic data were collected in August and September 2021 over the Northern Chukchi Borderland and Central Canada Basin from the R/V Sikuliaq. The data were acquired with two 520 cu inch GI airguns and a 200 meters (32 channels) streamer. The preliminary processing started by screening the bad traces caused by the broken hydrophone and misfires during acquisition. Bandpass and F-K filtering were applied to the traces. The bandpass filtering eliminates energy that is outside of the band of energy emitted by the airguns. The F-K filter is implemented by bringing the signal amplitude into the frequency-wavenumber (f-k) domain to exclude the reflection signal with the noise amplitude. Our seismic data contains multiples that interfere with the primary image, obscuring the data. These multiples usually occur when seismic signals are trapped in the water column. We utilized surface related multiple elimination (SRME) method to attenuate the multiples. Surface related multiple elimination is applied by developing multiple prediction models from the primary reflection and generating the high order and low order multiple to subtract or eliminate the multiple. We find the SRME method is improved adjusting the sediment velocity and the filter length. The bandpass and F-K filter show a significant improvement in the signal coherence. The SRME method is effective in improving the clarity and continuity of the primary reflectors. Profiles were generated by performing post-stack time migration. Post-stack migration was applied by summing all the reflected signals into a CDP gather, strengthen the coherent reflectors, then migrating or relocating the dipping reflector to its actual location and eliminating the diffraction effects. We have tied our interpretation to the previous project acquired in 2011 from the southern part of the Chukchi Borderland. The 2011 survey sailed over wells drilled by Shell in the late 80s on the Chukchi Shelf and directly tied the reflectors with the stratigraphy. The processed multichannel-seismic profiles from the Northern Chukchi Borderland show horsts with grabens continuous with those imaged from RV Langseth in 2011. These basins are filled with syn-rift and post-rift stratigraphy. Stratigraphic sequences imaged on Northwind Ridge are segmented by multiple unconformities and minor structures. The origin of these unconformities may be related to the opening of Canada Basin and multiple generations of glacial ice contact over the bathymetric high. The seismic profile on Canada basin showed a prominent feature recognized as a basement, which seems to support the interpretation of the extinct mid-ocean ridge as an unsegmented, ultra-slow spreading ridge.
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- Award ID(s):
- 1916575
- PAR ID:
- 10392709
- Date Published:
- Journal Name:
- Transactions American Geophysical Union
- ISSN:
- 0002-8606
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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