Segmentation of the Mid-Atlantic Ridge south of the Azores, based on acoustic classification of TOBI data

The European MARFLUX/ATJ project has investigated volcanic, tectonic and hydrothermal processes along 500 km of the Mid-Atlantic Ridge near the Azores. During cruises CD89-CD90, multibeam bathymetry and high-resolution TOBI sidescan sonar data were acquired and added to the existing Geographical Information System. From the Azores Triple Junction, between 35° and 38°N, the ridge runs 227°, oblique to the 100° spreading direction. It is partitioned into several short ridge segments dominated by tectonism rather than volcanism, and is characterised by abundant hydrothermal activity. Textural analysis quantifies the second-order statistics of TOBI imagery, enabling the detection of details invisible to the human eye. The results of this analysis are used to quantify the relationship between tectonism and volcanism along-axis, and suggest declining neovolcanic activity away from the Triple Junction. They show that the discontinuities are heavily sedimented, whereas the segments are mostly volcanic and the segment ends are more densely faulted. Textural analysis quantifies the differences in style and activity of the different spreading segments, and the evolution of the discontinuities.