| Title: |
Wide-Angle Seismic Imaging of Two Modes of Crustal Accretion in Mature Atlantic Ocean Crust |
| Authors: |
Davy, R. G.; Collier, J. S.; Henstock, T. J.; Goes, Saskia; Blundy, Jon; Harmon, Nick; Rychert, Catherine; Macpherson, Colin G.; van Hunen, Jeroen; Kendall, Mike; Wilkinson, Jamie; Davidson, Jon; Wilson, Marjorie; Cooper, George; Maunder, Benjamin; Bie, Lidong; Hicks, Stephen; Chichester, Ben; Tait, Stephen; Robertson, Richie; Latchman, Joan; Krüger, Frank; Collier, Jenny; Henstock, Tim; Allen, Robert; Butcher, Sophie; Castiello, Gabriella; Chen, Chen; Harkin, Caroline; Posse, Dan; Roche, Ben; Bird, Anna; Clegg, Andy; Pitcairn, Ben; Weeks, Martin; Kirk, Henning; Labahn, Erik |
| Contributors: |
Institut de Physique du Globe de Paris (IPGP - UMR_7154); Institut national des sciences de l'Univers (INSU - CNRS)-Institut National de l'Information Géographique et Forestière IGN (IGN)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité) |
| Source: |
ISSN: 2169-9313 ; EISSN: 2169-9356. |
| Publisher Information: |
CCSD; American Geophysical Union |
| Publication Year: |
2020 |
| Subject Terms: |
slow-spread oceanic crust; active-source seismic; tomography; oceanic core complexes; fracture zone; nontransform offset; [SDU]Sciences of the Universe [physics] |
| Description: |
International audience ; 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. |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| Relation: |
BIBCODE: 2020JGRB.12519100D |
| DOI: |
10.1029/2019JB019100 |
| Availability: |
https://insu.hal.science/insu-03584765; https://insu.hal.science/insu-03584765v1/document; https://insu.hal.science/insu-03584765v1/file/JGR%20Solid%20Earth%20-%202020%20-%20Davy%20-%20Wide%25u2010Angle%20Seismic%20Imaging%20of%20Two%20Modes%20of%20Crustal%20Accretion%20in%20Mature%20Atlantic%20Ocean%20Crust.pdf; https://doi.org/10.1029/2019JB019100 |
| Rights: |
http://hal.archives-ouvertes.fr/licences/copyright/ ; info:eu-repo/semantics/OpenAccess |
| Accession Number: |
edsbas.4A979D65 |
| Database: |
BASE |