Submersible study of an oceanic megamullion in the central North Atlantic
Author Posting. © American Geophysical Union, 2001. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 106, no. B8 (2001): 16145–16161, doi:10.1029/2001JB000373. Rec...
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/5773 2023-05-15T17:36:11+02:00 Submersible study of an oceanic megamullion in the central North Atlantic Tucholke, Brian E. Fujioka, Kantaro Ishihara, Takemi Hirth, Greg Kinoshita, Masataka 2001-08-10 application/pdf https://hdl.handle.net/1912/5773 en_US eng American Geophysical Union https://doi.org/10.1029/2001JB000373 Journal of Geophysical Research 106, no. B8 (2001): 16145–16161 https://hdl.handle.net/1912/5773 doi:10.1029/2001JB000373 Journal of Geophysical Research 106, no. B8 (2001): 16145–16161 doi:10.1029/2001JB000373 Article 2001 ftwhoas https://doi.org/10.1029/2001JB000373 2022-05-28T22:58:47Z Author Posting. © American Geophysical Union, 2001. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 106, no. B8 (2001): 16145–16161, doi:10.1029/2001JB000373. Recently discovered megamullions on the seafloor have been interpreted to be the exhumed footwalls of long-lived detachment faults operating near the ends of spreading segments in slow spreading crust. We conducted five submersible dives on one of these features just east of the rift valley in the Mid-Atlantic Ridge at 26°35′N and obtained visual, rock sample, gravity, and heat flow data along a transect from the breakaway zone (where the fault is interpreted to have first nucleated in ∼2.0–2.2 Ma crust) westward to near the termination (∼0.7 Ma). Our observations are consistent with the detachment fault hypothesis and show the following features. In the breakaway zone, faulted and steeply backtilted basaltic blocks suggest rotation above a deeper shear zone; the youngest normal faults in this sequence are interpreted to have evolved into the long-lived detachment fault. In younger crust the interpreted detachment surface rises as monotonously flat seafloor in a pair of broad, gently sloping domes that formed simultaneously along isochrons and are now thinly covered by sediment. The detachment surface is locally littered with basaltic debris that may have been clipped from the hanging wall. The domes coincide with a gravity high that continues along isochrons within the spreading segment. Modeling of on-bottom gravity measurements and recovery of serpentinites imply that mantle rises steeply and is exposed within ∼7 km west of the breakaway but that rocks with intermediate densities prevail farther west. Within ∼5 km of the termination, small volcanic cones appear on the detachment surface, indicating melt input into the footwall. We interpret the megamullion to have developed during a phase of limited magmatism in the ... Article in Journal/Newspaper North Atlantic Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Mid-Atlantic Ridge Journal of Geophysical Research: Solid Earth 106 B8 16145 16161 |
institution |
Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
description |
Author Posting. © American Geophysical Union, 2001. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 106, no. B8 (2001): 16145–16161, doi:10.1029/2001JB000373. Recently discovered megamullions on the seafloor have been interpreted to be the exhumed footwalls of long-lived detachment faults operating near the ends of spreading segments in slow spreading crust. We conducted five submersible dives on one of these features just east of the rift valley in the Mid-Atlantic Ridge at 26°35′N and obtained visual, rock sample, gravity, and heat flow data along a transect from the breakaway zone (where the fault is interpreted to have first nucleated in ∼2.0–2.2 Ma crust) westward to near the termination (∼0.7 Ma). Our observations are consistent with the detachment fault hypothesis and show the following features. In the breakaway zone, faulted and steeply backtilted basaltic blocks suggest rotation above a deeper shear zone; the youngest normal faults in this sequence are interpreted to have evolved into the long-lived detachment fault. In younger crust the interpreted detachment surface rises as monotonously flat seafloor in a pair of broad, gently sloping domes that formed simultaneously along isochrons and are now thinly covered by sediment. The detachment surface is locally littered with basaltic debris that may have been clipped from the hanging wall. The domes coincide with a gravity high that continues along isochrons within the spreading segment. Modeling of on-bottom gravity measurements and recovery of serpentinites imply that mantle rises steeply and is exposed within ∼7 km west of the breakaway but that rocks with intermediate densities prevail farther west. Within ∼5 km of the termination, small volcanic cones appear on the detachment surface, indicating melt input into the footwall. We interpret the megamullion to have developed during a phase of limited magmatism in the ... |
format |
Article in Journal/Newspaper |
author |
Tucholke, Brian E. Fujioka, Kantaro Ishihara, Takemi Hirth, Greg Kinoshita, Masataka |
spellingShingle |
Tucholke, Brian E. Fujioka, Kantaro Ishihara, Takemi Hirth, Greg Kinoshita, Masataka Submersible study of an oceanic megamullion in the central North Atlantic |
author_facet |
Tucholke, Brian E. Fujioka, Kantaro Ishihara, Takemi Hirth, Greg Kinoshita, Masataka |
author_sort |
Tucholke, Brian E. |
title |
Submersible study of an oceanic megamullion in the central North Atlantic |
title_short |
Submersible study of an oceanic megamullion in the central North Atlantic |
title_full |
Submersible study of an oceanic megamullion in the central North Atlantic |
title_fullStr |
Submersible study of an oceanic megamullion in the central North Atlantic |
title_full_unstemmed |
Submersible study of an oceanic megamullion in the central North Atlantic |
title_sort |
submersible study of an oceanic megamullion in the central north atlantic |
publisher |
American Geophysical Union |
publishDate |
2001 |
url |
https://hdl.handle.net/1912/5773 |
geographic |
Mid-Atlantic Ridge |
geographic_facet |
Mid-Atlantic Ridge |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Journal of Geophysical Research 106, no. B8 (2001): 16145–16161 doi:10.1029/2001JB000373 |
op_relation |
https://doi.org/10.1029/2001JB000373 Journal of Geophysical Research 106, no. B8 (2001): 16145–16161 https://hdl.handle.net/1912/5773 doi:10.1029/2001JB000373 |
op_doi |
https://doi.org/10.1029/2001JB000373 |
container_title |
Journal of Geophysical Research: Solid Earth |
container_volume |
106 |
container_issue |
B8 |
container_start_page |
16145 |
op_container_end_page |
16161 |
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1766135591864369152 |