Anomalous seismic crustal structure of oceanic fracture zones
The seismic structure of crust found within fracture zones falls outside the range of velocity structures observed for normal oceanic crust in the North Atlantic. The crust in fracture zones is frequently very thin and is characterized by low crustal velocities and by the conspicuous absence of a re...
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1984
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fthighwire:oai:open-archive.highwire.org:gji:79/3/779 2023-05-15T17:34:35+02:00 Anomalous seismic crustal structure of oceanic fracture zones White, Robert S. Detrick, Robert S. Sinha, Martin C. Cormier, Marie H. 1984-12-01 00:00:00.0 text/html http://gji.oxfordjournals.org/cgi/content/short/79/3/779 https://doi.org/10.1111/j.1365-246X.1984.tb02868.x en eng Oxford University Press http://gji.oxfordjournals.org/cgi/content/short/79/3/779 http://dx.doi.org/10.1111/j.1365-246X.1984.tb02868.x Copyright (C) 1984, Oxford University Press Articles TEXT 1984 fthighwire https://doi.org/10.1111/j.1365-246X.1984.tb02868.x 2015-02-28T23:32:38Z The seismic structure of crust found within fracture zones falls outside the range of velocity structures observed for normal oceanic crust in the North Atlantic. The crust in fracture zones is frequently very thin and is characterized by low crustal velocities and by the conspicuous absence of a refractor with a velocity typical of oceanic layer 3. Anomalous crust is present in both large- and small-offset fracture zones. Since they are among the most common tectonic features in the ocean basins, and are particularly closely spaced on slow-spreading ridges, fracture zones represent a major source of seismic crustal heterogeneity. We interpret the anomalous crust as a thin, intensely fractured, faulted and hydrothermally altered basaltic and gabbroic section overlying ultramafics that, in places, are extensively serpentinized. The unusually thin crust found within fracture zones and the gradual crustal thinning over a distance of several tens of kilometres on either side of the fracture zones can be explained by two main processes; firstly the cold lithosphere edge opposite the spreading centre at the ridgetransform intersection modifies the normal intrusive and extrusive processes of the spreading centre leading to the accretion of an anomalous and thin igneous section; and secondly each spreading ridge segment is fed from a separate subcrustal magma supply point, so as the magma flows laterally down the spreading centre it generates a crustal section of decreasing thickness, culminating in the very thin crust of the fracture zones at either end of the ridge segment. Text North Atlantic HighWire Press (Stanford University) Geophysical Journal International 79 3 779 798 |
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Articles White, Robert S. Detrick, Robert S. Sinha, Martin C. Cormier, Marie H. Anomalous seismic crustal structure of oceanic fracture zones |
topic_facet |
Articles |
description |
The seismic structure of crust found within fracture zones falls outside the range of velocity structures observed for normal oceanic crust in the North Atlantic. The crust in fracture zones is frequently very thin and is characterized by low crustal velocities and by the conspicuous absence of a refractor with a velocity typical of oceanic layer 3. Anomalous crust is present in both large- and small-offset fracture zones. Since they are among the most common tectonic features in the ocean basins, and are particularly closely spaced on slow-spreading ridges, fracture zones represent a major source of seismic crustal heterogeneity. We interpret the anomalous crust as a thin, intensely fractured, faulted and hydrothermally altered basaltic and gabbroic section overlying ultramafics that, in places, are extensively serpentinized. The unusually thin crust found within fracture zones and the gradual crustal thinning over a distance of several tens of kilometres on either side of the fracture zones can be explained by two main processes; firstly the cold lithosphere edge opposite the spreading centre at the ridgetransform intersection modifies the normal intrusive and extrusive processes of the spreading centre leading to the accretion of an anomalous and thin igneous section; and secondly each spreading ridge segment is fed from a separate subcrustal magma supply point, so as the magma flows laterally down the spreading centre it generates a crustal section of decreasing thickness, culminating in the very thin crust of the fracture zones at either end of the ridge segment. |
format |
Text |
author |
White, Robert S. Detrick, Robert S. Sinha, Martin C. Cormier, Marie H. |
author_facet |
White, Robert S. Detrick, Robert S. Sinha, Martin C. Cormier, Marie H. |
author_sort |
White, Robert S. |
title |
Anomalous seismic crustal structure of oceanic fracture zones |
title_short |
Anomalous seismic crustal structure of oceanic fracture zones |
title_full |
Anomalous seismic crustal structure of oceanic fracture zones |
title_fullStr |
Anomalous seismic crustal structure of oceanic fracture zones |
title_full_unstemmed |
Anomalous seismic crustal structure of oceanic fracture zones |
title_sort |
anomalous seismic crustal structure of oceanic fracture zones |
publisher |
Oxford University Press |
publishDate |
1984 |
url |
http://gji.oxfordjournals.org/cgi/content/short/79/3/779 https://doi.org/10.1111/j.1365-246X.1984.tb02868.x |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
http://gji.oxfordjournals.org/cgi/content/short/79/3/779 http://dx.doi.org/10.1111/j.1365-246X.1984.tb02868.x |
op_rights |
Copyright (C) 1984, Oxford University Press |
op_doi |
https://doi.org/10.1111/j.1365-246X.1984.tb02868.x |
container_title |
Geophysical Journal International |
container_volume |
79 |
container_issue |
3 |
container_start_page |
779 |
op_container_end_page |
798 |
_version_ |
1766133464400134144 |