Assessing Along-Axis Continuity of Oceanic Detachment Faults using microearthquakes near 13°N, Mid-Atlantic Ridge
Abstract
Observations of oceanic detachment faulting in slow-spreading ridges have mostly been limited to seabed sampling and mapping, leaving many questions about the structure and processes taking place beneath the seafloor unanswered. One of the most critical outstanding questions today is whether or not along-axis adjacent oceanic detachments are connected by a continuous fault in the sub-surface. Here we present data from network of 58 ocean bottom seismographs (OBS), deployed on the Mid-Atlantic Ridge at 13°N that extends ~30 km along the ridge axis and provides dense spatial coverage over two active detachment faults and the intervening ridge axis. This network, which was deployed by UK scientists to record airgun shots from an active-source seismic experiment, contains over 15,000 local microearthquakes, recorded during 12 days when the airguns were not being used. The spatial pattern of microearthquakes between the two adjacent core complexes at 13°20'N and 13°30'N is discontinuous, suggesting that they are unlikely to be connected by a single fault surface. The pattern of microearthquakes also shows that the core complex at 13°30'N is being dissected by a linear tectono-magmatic feature, and closely matches the pattern of faults and fissures revealed by 1m-resolution near-bottom bathymetric data collected at the crest of this massif. These results indicate that oceanic detachments, and the core complexes that they develop, are likely to be temporally ephemeral and spatially distinct, and subject to dissection and abandonment over length scales of tens of kilometers.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T12C..01P
- Keywords:
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- 3035 Midocean ridge processes;
- MARINE GEOLOGY AND GEOPHYSICS;
- 8034 Rheology and friction of fault zones;
- STRUCTURAL GEOLOGY;
- 8135 Hydrothermal systems;
- TECTONOPHYSICS;
- 8178 Tectonics and magmatism;
- TECTONOPHYSICS