Wide‐Angle Seismic Imaging of Two Modes of Crustal Accretion in Mature Atlantic Ocean Crust
| العنوان: | Wide‐Angle Seismic Imaging of Two Modes of Crustal Accretion in Mature Atlantic Ocean Crust |
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| المؤلفون: | Martin Weeks, Gabriella Castiello, J. Collier, Frank Kruger, Lidong Bie, Marjorie Wilson, Jeroen van Hunen, Anna Bird, B. Chichester, Jon D Blundy, Andy Clegg, Nicholas Harmon, R. G. Davy, Richie Robertson, Henning Kirk, Joan L. Latchman, Andreas Rietbrock, T. Henstock, Timothy J. Henstock, Catherine A. Rychert, Stephen Hicks, Colin G. Macpherson, Ben Pitcairn, Ben Roche, Mike Kendall, Dan Posse, Sophie Butcher, Jamie J. Wilkinson, Chen Chen, Jenny S. Collier, Benjamin Maunder, Jon P. Davidson, Saskia Goes, Caroline Harkin, Stephen Tait, George F. Cooper, Erik Labahn, Robert Allen |
| المساهمون: | Natural Environment Research Council (NERC) |
| المصدر: | Journal of geophysical research / Solid earth, 125 (6) |
| بيانات النشر: | American Geophysical Union (AGU), 2020. |
| سنة النشر: | 2020 |
| مصطلحات موضوعية: | 010504 meteorology & atmospheric sciences, Velocity gradient, Geophysical imaging, Physics, Fracture zone, Crust, 0404 Geophysics, Classification of discontinuities, 01 natural sciences, Mantle (geology), Geophysics, 0403 Geology, Space and Planetary Science, Geochemistry and Petrology, Seismic velocity, Oceanic crust, Earth and Planetary Sciences (miscellaneous), 0402 Geochemistry, ddc:530, Petrology, Geology, 0105 earth and related environmental sciences |
| الوصف: | We present a high‐resolution 2‐D P‐wave velocity model from a 225‐km‐long active seismic profile, collected over ~60–75 Ma central Atlantic crust. The profile crosses five ridge segments separated by a transform and three nontransform offsets. All ridge discontinuities share similar primary characteristics, independent of the offset. We identify two types of crustal segment. The first displays a classic two‐layer velocity structure with a high gradient Layer 2 (~0.9 s$^{−1}$) above a lower gradient Layer 3 (0.2 s$^{−1}$). Here, PmP coincides with the 7.5 km s$^{−1}$ contour, and velocity increases to >7.8 km s$^{−1}$ within 1 km below. We interpret these segments as magmatically robust, with PmP representing a petrological boundary between crust and mantle. The second has a reduced contrast in velocity gradient between the upper and lower crust and PmP shallower than the 7.5 km s$^{−1}$ contour. We interpret these segments as tectonically dominated, with PmP representing a serpentinized (alteration) front. While velocity‐depth profiles fit within previous envelopes for slow‐spreading crust, our results suggest that such generalizations give a misleading impression of uniformity. We estimate that the two crustal styles are present in equal proportions on the floor of the Atlantic. Within two tectonically dominated segments, we make the first wide‐angle seismic identifications of buried oceanic core complexes in mature (>20 Ma) Atlantic Ocean crust. They have a ~20‐km‐wide “domal” morphology with shallow basement and increased upper crustal velocities. We interpret their midcrustal seismic velocity inversions as alteration and rock‐type assemblage contrasts across crustal‐scale detachment faults. |
| وصف الملف: | application/pdf |
| تدمد: | 2169-9356 2169-9313 0148-0227 2156-2202 |
| DOI: | 10.1029/2019jb019100 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::eafddf68c8a1a6ca67c06756d3c3d034 https://doi.org/10.1029/2019jb019100 |
| Rights: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....eafddf68c8a1a6ca67c06756d3c3d034 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 21699356 21699313 01480227 21562202 |
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| DOI: | 10.1029/2019jb019100 |