The Final Stages of Slip and Volcanism on an Oceanic Detachment Fault at 13°48′N, Mid‐Atlantic Ridge
Abstract While processes associated with initiation and maintenance of oceanic detachment faults are becoming better constrained, much less is known about the tectonic and magmatic conditions that lead to fault abandonment. Here we present results from near‐bottom investigations using the submersibl...
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| Format: | Article |
| Language: | English |
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Wiley
2018-09-01
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| Series: | Geochemistry, Geophysics, Geosystems |
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| Online Access: | https://doi.org/10.1029/2018GC007536 |
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| author | R. E. Parnell‐Turner E. Mittelstaedt M. D. Kurz M. P. Jones S. A. Soule F. Klein V. D. Wanless D. J. Fornari |
| author_facet | R. E. Parnell‐Turner E. Mittelstaedt M. D. Kurz M. P. Jones S. A. Soule F. Klein V. D. Wanless D. J. Fornari |
| author_sort | R. E. Parnell‐Turner |
| collection | DOAJ |
| description | Abstract While processes associated with initiation and maintenance of oceanic detachment faults are becoming better constrained, much less is known about the tectonic and magmatic conditions that lead to fault abandonment. Here we present results from near‐bottom investigations using the submersible Alvin and autonomous underwater vehicle Sentry at a recently extinct detachment fault near 13°48′N, Mid‐Atlantic Ridge, that allow documentation of the final stages of fault activity and magmatism. Seafloor imagery, sampling, and near‐bottom magnetic data show that the detachment footwall is intersected by an ~850 m‐wide volcanic outcrop including pillow lavas. Saturation pressures in these vesicular basalts, based on dissolved H2O and CO2, are less than their collection pressures, which could be explained by eruption at a shallower level than their present depth. Sub‐bottom profiles reveal that sediment thickness, a loose proxy for seafloor age, is ~2 m greater on top of the volcanic terrain than on the footwall adjacent to the hanging‐wall cutoff. This difference could be explained by current‐driven erosion in the axial valley or by continued slip after volcanic emplacement, on either a newly formed or pre‐existing fault. Since current speeds near the footwall are unlikely to be sufficient to cause significant erosion, we favor the hypothesis that detachment slip continued after the episode of magmatism, consistent with growing evidence that oceanic detachments can continue to slip despite hosting magmatic intrusions. |
| format | Article |
| id | doaj-art-186be8a32a3c4bbd937ce40d4bb6ffdd |
| institution | Kabale University |
| issn | 1525-2027 |
| language | English |
| publishDate | 2018-09-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj-art-186be8a32a3c4bbd937ce40d4bb6ffdd2025-08-20T03:24:47ZengWileyGeochemistry, Geophysics, Geosystems1525-20272018-09-011993115312710.1029/2018GC007536The Final Stages of Slip and Volcanism on an Oceanic Detachment Fault at 13°48′N, Mid‐Atlantic RidgeR. E. Parnell‐Turner0E. Mittelstaedt1M. D. Kurz2M. P. Jones3S. A. Soule4F. Klein5V. D. Wanless6D. J. Fornari7Woods Hole Oceanographic Institution Woods Hole MA USADepartment of Geological Sciences University of Idaho Moscow ID USAWoods Hole Oceanographic Institution Woods Hole MA USAMassachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program in Oceanography Woods Hole MA USAWoods Hole Oceanographic Institution Woods Hole MA USAWoods Hole Oceanographic Institution Woods Hole MA USADepartment of Geosciences Boise State University Boise ID USAWoods Hole Oceanographic Institution Woods Hole MA USAAbstract While processes associated with initiation and maintenance of oceanic detachment faults are becoming better constrained, much less is known about the tectonic and magmatic conditions that lead to fault abandonment. Here we present results from near‐bottom investigations using the submersible Alvin and autonomous underwater vehicle Sentry at a recently extinct detachment fault near 13°48′N, Mid‐Atlantic Ridge, that allow documentation of the final stages of fault activity and magmatism. Seafloor imagery, sampling, and near‐bottom magnetic data show that the detachment footwall is intersected by an ~850 m‐wide volcanic outcrop including pillow lavas. Saturation pressures in these vesicular basalts, based on dissolved H2O and CO2, are less than their collection pressures, which could be explained by eruption at a shallower level than their present depth. Sub‐bottom profiles reveal that sediment thickness, a loose proxy for seafloor age, is ~2 m greater on top of the volcanic terrain than on the footwall adjacent to the hanging‐wall cutoff. This difference could be explained by current‐driven erosion in the axial valley or by continued slip after volcanic emplacement, on either a newly formed or pre‐existing fault. Since current speeds near the footwall are unlikely to be sufficient to cause significant erosion, we favor the hypothesis that detachment slip continued after the episode of magmatism, consistent with growing evidence that oceanic detachments can continue to slip despite hosting magmatic intrusions.https://doi.org/10.1029/2018GC007536mid‐ocean ridgeoceanic detachment faultnear‐bottom geophysicsvolatile geochemistry |
| spellingShingle | R. E. Parnell‐Turner E. Mittelstaedt M. D. Kurz M. P. Jones S. A. Soule F. Klein V. D. Wanless D. J. Fornari The Final Stages of Slip and Volcanism on an Oceanic Detachment Fault at 13°48′N, Mid‐Atlantic Ridge Geochemistry, Geophysics, Geosystems mid‐ocean ridge oceanic detachment fault near‐bottom geophysics volatile geochemistry |
| title | The Final Stages of Slip and Volcanism on an Oceanic Detachment Fault at 13°48′N, Mid‐Atlantic Ridge |
| title_full | The Final Stages of Slip and Volcanism on an Oceanic Detachment Fault at 13°48′N, Mid‐Atlantic Ridge |
| title_fullStr | The Final Stages of Slip and Volcanism on an Oceanic Detachment Fault at 13°48′N, Mid‐Atlantic Ridge |
| title_full_unstemmed | The Final Stages of Slip and Volcanism on an Oceanic Detachment Fault at 13°48′N, Mid‐Atlantic Ridge |
| title_short | The Final Stages of Slip and Volcanism on an Oceanic Detachment Fault at 13°48′N, Mid‐Atlantic Ridge |
| title_sort | final stages of slip and volcanism on an oceanic detachment fault at 13°48 n mid atlantic ridge |
| topic | mid‐ocean ridge oceanic detachment fault near‐bottom geophysics volatile geochemistry |
| url | https://doi.org/10.1029/2018GC007536 |
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