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Volcanic-tectonic structure of the Mount Dent Oceanic Core Complex in the ultraslow mid-cayman spreading center determined from detailed seafloor investigation

Volcanic-tectonic structure of the Mount Dent Oceanic Core Complex in the ultraslow mid-cayman spreading center determined from detailed seafloor investigation
Volcanic-tectonic structure of the Mount Dent Oceanic Core Complex in the ultraslow mid-cayman spreading center determined from detailed seafloor investigation
The flanks of the ultraslow‐spreading Mid‐Cayman Spreading Center (MCSC) are characterized by domal massifs or oceanic core complexes (OCCs). The most prominent of these, Mount Dent, comprises lower‐crustal and upper‐mantle lithologies and hosts the Von Damm vent field ~12 km west of the axial deep. Here, presented autonomous underwater vehicle‐derived swath sonar (multibeam) mapping and deep‐towed side‐scan sonar imagery lead to our interpretation that: (i) slip along the OCC‐bounding detachment fault is ceasing, (ii) the termination zone, where detachment fault meets the hanging wall, is disintegrating, (iii) the domed surface of the OCC is cut by steep north‐south extensional faulting, and (iv) the breakaway zone is cut by outward facing faults. The Von Damm vent field and dispersed pockmarks on the OCC's south flank further suggest that hydrothermal fluid flow is pervasive within the faulted OCC. On the axial floor of the MCSC, bright acoustic backscatter and multibeam bathymetry reveal: (v) a volcanic detachment hanging wall, (vi) a major fault rifting the southern flank of Mount Dent, and (vii) a young axial volcanic ridge intersecting its northern flank. These observations are described by a conceptual model wherein detachment faulting and OCC exhumation are ceasing during an increase in magmatic intrusion, brittle deformation, and hydrothermal circulation within the OCC. Together, this high‐resolution view of the MCSC provides an instructive example of how OCCs, formed within an overall melt‐starved ultraslow spreading center, can undergo magmatism, hydrothermal activity, and faulting in much the same way as expected in magmatically more robust slow‐spreading centers elsewhere.
1525-2027
Haughton, G. A.
b28af40f-6589-43a5-9989-48973091a0db
Hayman, N. W.
11ecd365-e773-45ea-b8e3-75562edba8fa
Searle, R. C.
6652e8ea-1da8-4b39-9dea-b365dfeb8b49
Le Bas, T.
f0dbad80-bb38-412c-be77-b8b9faef1854
Murton, B. J.
9076d07f-a3c1-4f90-a5d5-99b27fe2cb12
Haughton, G. A.
b28af40f-6589-43a5-9989-48973091a0db
Hayman, N. W.
11ecd365-e773-45ea-b8e3-75562edba8fa
Searle, R. C.
6652e8ea-1da8-4b39-9dea-b365dfeb8b49
Le Bas, T.
f0dbad80-bb38-412c-be77-b8b9faef1854
Murton, B. J.
9076d07f-a3c1-4f90-a5d5-99b27fe2cb12

Haughton, G. A., Hayman, N. W., Searle, R. C., Le Bas, T. and Murton, B. J. (2019) Volcanic-tectonic structure of the Mount Dent Oceanic Core Complex in the ultraslow mid-cayman spreading center determined from detailed seafloor investigation. Geochemistry, Geophysics, Geosystems. (doi:10.1029/2018GC008032).

Record type: Article

Abstract

The flanks of the ultraslow‐spreading Mid‐Cayman Spreading Center (MCSC) are characterized by domal massifs or oceanic core complexes (OCCs). The most prominent of these, Mount Dent, comprises lower‐crustal and upper‐mantle lithologies and hosts the Von Damm vent field ~12 km west of the axial deep. Here, presented autonomous underwater vehicle‐derived swath sonar (multibeam) mapping and deep‐towed side‐scan sonar imagery lead to our interpretation that: (i) slip along the OCC‐bounding detachment fault is ceasing, (ii) the termination zone, where detachment fault meets the hanging wall, is disintegrating, (iii) the domed surface of the OCC is cut by steep north‐south extensional faulting, and (iv) the breakaway zone is cut by outward facing faults. The Von Damm vent field and dispersed pockmarks on the OCC's south flank further suggest that hydrothermal fluid flow is pervasive within the faulted OCC. On the axial floor of the MCSC, bright acoustic backscatter and multibeam bathymetry reveal: (v) a volcanic detachment hanging wall, (vi) a major fault rifting the southern flank of Mount Dent, and (vii) a young axial volcanic ridge intersecting its northern flank. These observations are described by a conceptual model wherein detachment faulting and OCC exhumation are ceasing during an increase in magmatic intrusion, brittle deformation, and hydrothermal circulation within the OCC. Together, this high‐resolution view of the MCSC provides an instructive example of how OCCs, formed within an overall melt‐starved ultraslow spreading center, can undergo magmatism, hydrothermal activity, and faulting in much the same way as expected in magmatically more robust slow‐spreading centers elsewhere.

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Accepted/In Press date: 23 January 2019
e-pub ahead of print date: 29 January 2019

Identifiers

Local EPrints ID: 429339
URI: https://eprints.soton.ac.uk/id/eprint/429339
ISSN: 1525-2027
PURE UUID: 0f833a4d-8098-45b1-9265-d2a915c72cbe

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Date deposited: 26 Mar 2019 17:30
Last modified: 19 Jul 2019 16:38

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Contributors

Author: G. A. Haughton
Author: N. W. Hayman
Author: R. C. Searle
Author: T. Le Bas
Author: B. J. Murton

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