Seismic signal penetration beneath postrift sills on the Newfoundland rifted margin.
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| Title: | Seismic signal penetration beneath postrift sills on the Newfoundland rifted margin. |
|---|---|
| Authors: | Shililngton, Donna J.1 djs@ldeo.columbia.edu, Hopper, John R.2 Ejrh@gevs.dek, Holbrook, W. Steven3 steveh@uwyo.edu |
| Source: | Geophysics. Sep/Oct2008, Vol. 73 Issue 5, pB99-B107. 9p. 2 Diagrams, 4 Graphs. |
| Subjects: | Seismic reflection method data processing, Seismic prospecting, Frequency spectra, Penetration mechanics |
| Geographic Terms: | Newfoundland & Labrador |
| Abstract: | Analysis of averaged, smoothed instantaneous frequency and amplitude of seismic-reflection data collected on the Newfoundland magma-starved rifted margin along the Ocean Drilling Program (ODP) leg 210 transect demonstrate that the transparency of "transitional" crust arises from poor signal penetration. In principle, the high-frequency spectral content and amplitude of seismic reflection data should decrease with increasing traveltime as a result of absorption, geometric spreading, and scattering so long as seismic energy continues to return from deeper levels of the subsurface. As a result, if average frequency and amplitude cease to decrease with depth, background noise, rather than returning seismic energy, likely dominates the record. Average frequency increases and average amplitude remains comparatively constant below bright reflections overlying transitional crust on the Newfoundland margin. Similar patterns are not observed at the sediment-basement contact farther seaward in oceanic crust where intracrustal reflections are apparent. In those records, both amplitude and frequency continue to decrease steadily for at least 2-3 s below the top of basement. We interpret these observations as evidence that signal penetration is comparatively poor beneath bright reflections overlying transitional basement. Consequently, the featureless appearance of transitional crust on the Newfoundland margin in seismic-reflection profiles cannot be used to make inferences about its physical properties; instead, only seismic characteristics observed in rare basement highs that rise above bright reflections in the lowermost sedimentary section can provide meaningful information. Weak signal penetration in this crustal domain is consistent with the results from site 1276 during ODP leg 210, where interlayered diabase sills and sediments were recovered above basement, which would be expected to result in high reflection coefficients and low signal penetration. The apparent lack of seismic penetration throughout the transition zone off Newfoundland also implies interlayered sills and sediments might be widespread over this crustal domain. [ABSTRACT FROM AUTHOR] |
| Copyright of Geophysics is the property of Society of Exploration Geophysicists and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Items | – Name: Title Label: Title Group: Ti Data: Seismic signal penetration beneath postrift sills on the Newfoundland rifted margin. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Shililngton%2C+Donna+J%2E%22">Shililngton, Donna J.</searchLink><relatesTo>1</relatesTo><i> djs@ldeo.columbia.edu</i><br /><searchLink fieldCode="AR" term="%22Hopper%2C+John+R%2E%22">Hopper, John R.</searchLink><relatesTo>2</relatesTo><i> Ejrh@gevs.dek</i><br /><searchLink fieldCode="AR" term="%22Holbrook%2C+W%2E+Steven%22">Holbrook, W. Steven</searchLink><relatesTo>3</relatesTo><i> steveh@uwyo.edu</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Geophysics%22">Geophysics</searchLink>. Sep/Oct2008, Vol. 73 Issue 5, pB99-B107. 9p. 2 Diagrams, 4 Graphs. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Seismic+reflection+method+data+processing%22">Seismic reflection method data processing</searchLink><br /><searchLink fieldCode="DE" term="%22Seismic+prospecting%22">Seismic prospecting</searchLink><br /><searchLink fieldCode="DE" term="%22Frequency+spectra%22">Frequency spectra</searchLink><br /><searchLink fieldCode="DE" term="%22Penetration+mechanics%22">Penetration mechanics</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Newfoundland+%26+Labrador%22">Newfoundland & Labrador</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Analysis of averaged, smoothed instantaneous frequency and amplitude of seismic-reflection data collected on the Newfoundland magma-starved rifted margin along the Ocean Drilling Program (ODP) leg 210 transect demonstrate that the transparency of "transitional" crust arises from poor signal penetration. In principle, the high-frequency spectral content and amplitude of seismic reflection data should decrease with increasing traveltime as a result of absorption, geometric spreading, and scattering so long as seismic energy continues to return from deeper levels of the subsurface. As a result, if average frequency and amplitude cease to decrease with depth, background noise, rather than returning seismic energy, likely dominates the record. Average frequency increases and average amplitude remains comparatively constant below bright reflections overlying transitional crust on the Newfoundland margin. Similar patterns are not observed at the sediment-basement contact farther seaward in oceanic crust where intracrustal reflections are apparent. In those records, both amplitude and frequency continue to decrease steadily for at least 2-3 s below the top of basement. We interpret these observations as evidence that signal penetration is comparatively poor beneath bright reflections overlying transitional basement. Consequently, the featureless appearance of transitional crust on the Newfoundland margin in seismic-reflection profiles cannot be used to make inferences about its physical properties; instead, only seismic characteristics observed in rare basement highs that rise above bright reflections in the lowermost sedimentary section can provide meaningful information. Weak signal penetration in this crustal domain is consistent with the results from site 1276 during ODP leg 210, where interlayered diabase sills and sediments were recovered above basement, which would be expected to result in high reflection coefficients and low signal penetration. The apparent lack of seismic penetration throughout the transition zone off Newfoundland also implies interlayered sills and sediments might be widespread over this crustal domain. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Geophysics is the property of Society of Exploration Geophysicists and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1190/1.2972131 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 9 StartPage: B99 Subjects: – SubjectFull: Seismic reflection method data processing Type: general – SubjectFull: Seismic prospecting Type: general – SubjectFull: Frequency spectra Type: general – SubjectFull: Penetration mechanics Type: general – SubjectFull: Newfoundland & Labrador Type: general Titles: – TitleFull: Seismic signal penetration beneath postrift sills on the Newfoundland rifted margin. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Shililngton, Donna J. – PersonEntity: Name: NameFull: Hopper, John R. – PersonEntity: Name: NameFull: Holbrook, W. Steven IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 09 Text: Sep/Oct2008 Type: published Y: 2008 Identifiers: – Type: issn-print Value: 00168033 Numbering: – Type: volume Value: 73 – Type: issue Value: 5 Titles: – TitleFull: Geophysics Type: main |
| ResultId | 1 |
