New geophysical data from the northern Cordillera: preliminary interpretations and implications for the tectonics and deep geology
In this paper we analyze recently acquired geophysical data from the northern Cordillera and their relation to the mapped geology. A prominent gravity high (> −45 mGal (1 Gal = 1 cm/s 2 )) coincides with a magnetic low and an aseismic region in west-central Yukon where the underlying geology...
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1994
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crcansciencepubl:10.1139/e94-081 2023-12-17T10:51:36+01:00 New geophysical data from the northern Cordillera: preliminary interpretations and implications for the tectonics and deep geology Lowe, C. Horner, R. B. Mortensen, J. K. Johnston, S. T. Roots, C. F. 1994 http://dx.doi.org/10.1139/e94-081 http://www.nrcresearchpress.com/doi/pdf/10.1139/e94-081 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 31, issue 6, page 891-904 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 1994 crcansciencepubl https://doi.org/10.1139/e94-081 2023-11-19T13:39:05Z In this paper we analyze recently acquired geophysical data from the northern Cordillera and their relation to the mapped geology. A prominent gravity high (> −45 mGal (1 Gal = 1 cm/s 2 )) coincides with a magnetic low and an aseismic region in west-central Yukon where the underlying geology is dominated by quartzo-feldspathic rocks having moderate densities. Extension (~15%), magmatic underplating, and accretion of the anomalous region onto oceanic crust are three possible explanations.Magnetic, gravity, and seismicity data all show significant differences in the physical state of the crust on either side of the Tintina Fault and, together with geological data indicating large offset, suggest it was once a major crustal-scale strike-slip fault. The new gravity data also delineate an arcuate zone of steep gradients (up to 1.4 mGal/km) in the miogeocline, which may correlate with a west-dipping Proterozoic basement ramp mapped on deep seismic sections farther to the north and a transition from thin (east) to thick sediment cover (west). Seismicity data show that current tectonic activity is concentrated along the Pacific – North America plate margin in southwestern Yukon and adjacent Alaska and, although there is a marked decrease in activity inland of this margin, notable concentrations occur along the Denali Fault System and in the eastern miogeocline. There is a distinct absence of earthquakes in parts of the Selwyn Basin and in the northern Yukon–Tanana Terrane. Limited field studies suggest activity is confined to the upper 10–15 km of the crust. Article in Journal/Newspaper Alaska Yukon Canadian Science Publishing (via Crossref) Yukon Pacific Selwyn ENVELOPE(-138.287,-138.287,62.799,62.799) Canadian Journal of Earth Sciences 31 6 891 904 |
institution |
Open Polar |
collection |
Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Lowe, C. Horner, R. B. Mortensen, J. K. Johnston, S. T. Roots, C. F. New geophysical data from the northern Cordillera: preliminary interpretations and implications for the tectonics and deep geology |
topic_facet |
General Earth and Planetary Sciences |
description |
In this paper we analyze recently acquired geophysical data from the northern Cordillera and their relation to the mapped geology. A prominent gravity high (> −45 mGal (1 Gal = 1 cm/s 2 )) coincides with a magnetic low and an aseismic region in west-central Yukon where the underlying geology is dominated by quartzo-feldspathic rocks having moderate densities. Extension (~15%), magmatic underplating, and accretion of the anomalous region onto oceanic crust are three possible explanations.Magnetic, gravity, and seismicity data all show significant differences in the physical state of the crust on either side of the Tintina Fault and, together with geological data indicating large offset, suggest it was once a major crustal-scale strike-slip fault. The new gravity data also delineate an arcuate zone of steep gradients (up to 1.4 mGal/km) in the miogeocline, which may correlate with a west-dipping Proterozoic basement ramp mapped on deep seismic sections farther to the north and a transition from thin (east) to thick sediment cover (west). Seismicity data show that current tectonic activity is concentrated along the Pacific – North America plate margin in southwestern Yukon and adjacent Alaska and, although there is a marked decrease in activity inland of this margin, notable concentrations occur along the Denali Fault System and in the eastern miogeocline. There is a distinct absence of earthquakes in parts of the Selwyn Basin and in the northern Yukon–Tanana Terrane. Limited field studies suggest activity is confined to the upper 10–15 km of the crust. |
format |
Article in Journal/Newspaper |
author |
Lowe, C. Horner, R. B. Mortensen, J. K. Johnston, S. T. Roots, C. F. |
author_facet |
Lowe, C. Horner, R. B. Mortensen, J. K. Johnston, S. T. Roots, C. F. |
author_sort |
Lowe, C. |
title |
New geophysical data from the northern Cordillera: preliminary interpretations and implications for the tectonics and deep geology |
title_short |
New geophysical data from the northern Cordillera: preliminary interpretations and implications for the tectonics and deep geology |
title_full |
New geophysical data from the northern Cordillera: preliminary interpretations and implications for the tectonics and deep geology |
title_fullStr |
New geophysical data from the northern Cordillera: preliminary interpretations and implications for the tectonics and deep geology |
title_full_unstemmed |
New geophysical data from the northern Cordillera: preliminary interpretations and implications for the tectonics and deep geology |
title_sort |
new geophysical data from the northern cordillera: preliminary interpretations and implications for the tectonics and deep geology |
publisher |
Canadian Science Publishing |
publishDate |
1994 |
url |
http://dx.doi.org/10.1139/e94-081 http://www.nrcresearchpress.com/doi/pdf/10.1139/e94-081 |
long_lat |
ENVELOPE(-138.287,-138.287,62.799,62.799) |
geographic |
Yukon Pacific Selwyn |
geographic_facet |
Yukon Pacific Selwyn |
genre |
Alaska Yukon |
genre_facet |
Alaska Yukon |
op_source |
Canadian Journal of Earth Sciences volume 31, issue 6, page 891-904 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e94-081 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
31 |
container_issue |
6 |
container_start_page |
891 |
op_container_end_page |
904 |
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1785576923665006592 |