Crustal structure beneath Hudson Bay from ambient-noise tomography: implications for basin formation
The Hudson Bay basin is the least studied of four major Phanerozoic intracratonic basins in North America and the mechanism by which it formed remains ambiguous. We investigate the crustal structure of Hudson Bay based on ambient-noise tomography, using 21 months of continuous recordings from 37 bro...
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fthighwire:oai:open-archive.highwire.org:gji:184/1/65 2023-05-15T16:35:11+02:00 Crustal structure beneath Hudson Bay from ambient-noise tomography: implications for basin formation Pawlak, Agnieszka Eaton, David W. Bastow, Ian D. Kendall, J-Michael Helffrich, George Wookey, James Snyder, David 2011-01-01 00:00:00.0 text/html http://gji.oxfordjournals.org/cgi/content/short/184/1/65 https://doi.org/10.1111/j.1365-246X.2010.04828.x en eng Oxford University Press http://gji.oxfordjournals.org/cgi/content/short/184/1/65 http://dx.doi.org/10.1111/j.1365-246X.2010.04828.x Copyright (C) 2011, Oxford University Press Geodynamics and Tectonics TEXT 2011 fthighwire https://doi.org/10.1111/j.1365-246X.2010.04828.x 2016-11-16T18:43:39Z The Hudson Bay basin is the least studied of four major Phanerozoic intracratonic basins in North America and the mechanism by which it formed remains ambiguous. We investigate the crustal structure of Hudson Bay based on ambient-noise tomography, using 21 months of continuous recordings from 37 broad-band seismograph stations that encircle the Bay. Green's functions that emerge from the cross correlation of these ambient noise recordings are dominated by fundamental-mode Rayleigh waves. In the microseismic period band (5–20 s), these signals are most prominently expressed in certain preferred azimuths indicative of stationary coastal source regions in southern Alaska and Labrador. Seasonal variations are subtle but consistent with more energetic noise sources during winter months, when wave heights in the Pacific and north Atlantic are larger than in the summer. Noise emanating from Hudson Bay does not appear to contribute significantly to the cross correlograms. Group-velocity dispersion curves are obtained by time-frequency analysis of cross-correlation functions. We test and implement a signal-to-noise ratio (SNR) selection method for producing one-sided cross correlograms, which yields better-defined dispersion ridges than the standard two-sided averaging approach. Tomographic maps and cross sections obtained in the 5–40 s period range reveal significantly lower crustal velocities beneath Hudson Bay than in the bounding Archean Superior craton. The lowest mid-crustal velocities correspond to a previously determined region of maximum lithospheric stretching near the centre of the basin. Pseudosections extracted from the tomographic inversions along profiles across Hudson Bay provide the first compelling direct evidence for crustal thinning beneath the basin. Our results are consistent with a recent estimate of 3 km of crustal thinning, but not consistent with a proposed model for basin subsidence triggered by eclogitization of a remnant crustal root. Text Hudson Bay North Atlantic Alaska HighWire Press (Stanford University) Hudson Hudson Bay Pacific Geophysical Journal International 184 1 65 82 |
institution |
Open Polar |
collection |
HighWire Press (Stanford University) |
op_collection_id |
fthighwire |
language |
English |
topic |
Geodynamics and Tectonics |
spellingShingle |
Geodynamics and Tectonics Pawlak, Agnieszka Eaton, David W. Bastow, Ian D. Kendall, J-Michael Helffrich, George Wookey, James Snyder, David Crustal structure beneath Hudson Bay from ambient-noise tomography: implications for basin formation |
topic_facet |
Geodynamics and Tectonics |
description |
The Hudson Bay basin is the least studied of four major Phanerozoic intracratonic basins in North America and the mechanism by which it formed remains ambiguous. We investigate the crustal structure of Hudson Bay based on ambient-noise tomography, using 21 months of continuous recordings from 37 broad-band seismograph stations that encircle the Bay. Green's functions that emerge from the cross correlation of these ambient noise recordings are dominated by fundamental-mode Rayleigh waves. In the microseismic period band (5–20 s), these signals are most prominently expressed in certain preferred azimuths indicative of stationary coastal source regions in southern Alaska and Labrador. Seasonal variations are subtle but consistent with more energetic noise sources during winter months, when wave heights in the Pacific and north Atlantic are larger than in the summer. Noise emanating from Hudson Bay does not appear to contribute significantly to the cross correlograms. Group-velocity dispersion curves are obtained by time-frequency analysis of cross-correlation functions. We test and implement a signal-to-noise ratio (SNR) selection method for producing one-sided cross correlograms, which yields better-defined dispersion ridges than the standard two-sided averaging approach. Tomographic maps and cross sections obtained in the 5–40 s period range reveal significantly lower crustal velocities beneath Hudson Bay than in the bounding Archean Superior craton. The lowest mid-crustal velocities correspond to a previously determined region of maximum lithospheric stretching near the centre of the basin. Pseudosections extracted from the tomographic inversions along profiles across Hudson Bay provide the first compelling direct evidence for crustal thinning beneath the basin. Our results are consistent with a recent estimate of 3 km of crustal thinning, but not consistent with a proposed model for basin subsidence triggered by eclogitization of a remnant crustal root. |
format |
Text |
author |
Pawlak, Agnieszka Eaton, David W. Bastow, Ian D. Kendall, J-Michael Helffrich, George Wookey, James Snyder, David |
author_facet |
Pawlak, Agnieszka Eaton, David W. Bastow, Ian D. Kendall, J-Michael Helffrich, George Wookey, James Snyder, David |
author_sort |
Pawlak, Agnieszka |
title |
Crustal structure beneath Hudson Bay from ambient-noise tomography: implications for basin formation |
title_short |
Crustal structure beneath Hudson Bay from ambient-noise tomography: implications for basin formation |
title_full |
Crustal structure beneath Hudson Bay from ambient-noise tomography: implications for basin formation |
title_fullStr |
Crustal structure beneath Hudson Bay from ambient-noise tomography: implications for basin formation |
title_full_unstemmed |
Crustal structure beneath Hudson Bay from ambient-noise tomography: implications for basin formation |
title_sort |
crustal structure beneath hudson bay from ambient-noise tomography: implications for basin formation |
publisher |
Oxford University Press |
publishDate |
2011 |
url |
http://gji.oxfordjournals.org/cgi/content/short/184/1/65 https://doi.org/10.1111/j.1365-246X.2010.04828.x |
geographic |
Hudson Hudson Bay Pacific |
geographic_facet |
Hudson Hudson Bay Pacific |
genre |
Hudson Bay North Atlantic Alaska |
genre_facet |
Hudson Bay North Atlantic Alaska |
op_relation |
http://gji.oxfordjournals.org/cgi/content/short/184/1/65 http://dx.doi.org/10.1111/j.1365-246X.2010.04828.x |
op_rights |
Copyright (C) 2011, Oxford University Press |
op_doi |
https://doi.org/10.1111/j.1365-246X.2010.04828.x |
container_title |
Geophysical Journal International |
container_volume |
184 |
container_issue |
1 |
container_start_page |
65 |
op_container_end_page |
82 |
_version_ |
1766025360386818048 |