HR: 0800h
AN: T41E-1347    [Abstracts]
TI: Numerical modelling of Non Transform Discontinuity geometries: Implications for ridge structure, volcano-tectonic fabric development and hydrothermal activity at segment ends
AU: * Tyler, S
EM: st1@noc.soton.ac.uk
AF: Challenger Division for Seafloor Processes, National Oceanography Centre, European Way, Southampton, SO14 3ZH United Kingdom
AU: Bull, J
EM: bull@soton.ac.uk
AF: School of Ocean and Earth Sciences, National Oceanography Centre, European Way, Southampton, SO14 3ZH United Kingdom
AU: Parson, L
EM: lmp@noc.soton.ac.uk
AF: Challenger Division for Seafloor Processes, National Oceanography Centre, European Way, Southampton, SO14 3ZH United Kingdom
AU: Tuckwell, G
EM: g.w.tuckwell@esci.keele.ac.uk
AF: Applied & Environmental Geophysics Research Group, School of Physical and Geographical Sciences, Keele University, Keele, ST5 5BG United Kingdom
AB: Non Transform Discontinuities (NTDs) are a fundamental component of ocean ridge structure and geometry partitioning spreading centres into spatially and temporally independent segments. We use finite difference numerical models to understand the stress distributions associated with a range of NTD geometries. We also apply the models to rotations of volcano-tectonic fabrics observed within NTDs along the Central Indian Ridge (CIR) from high resolution sidescan and bathymetry data. The CIR is an intermediate spreading ridge and within our study area between 18S and 21S, eight NTDs are identified, three of which are used for this study. The modelling results show a dominant component of along-axis offset for the stress field rotations. Model correlation and co-location with the CIR NTDs highlights important differences between the interpreted segment tips and the tips predicted by the mechanical models. We propose that segments interpreted from morphological and volcano-tectonic observations may overlook fundamental components of segment structure. The results indicate that morphologically defined segments are composed of an effective segment behaving at the scale of this study as cracks opening under a tensile stress in an elastic medium and a damage zone behaving inelastically between the effective segment tip and the NTD. The damage zone is broadly analogous to the process zone described in fracture mechanics. The damage zone if well developed is associated with crustal softening through significant tectonism in a region of high magnitude stresses ahead of the segment tip. One significant property of the damage zone is an increase in the permeability of the crust. We therefore propose that the damage zone coupled with a suitable heat supply from serpentinisation or along-axis transport of heat may be a favourable site for the development of hydrothermal systems
DE: 3017 Hydrothermal systems (0450, 1034, 3616, 4832, 8135, 8424)
DE: 3035 Midocean ridge processes
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 3075 Submarine tectonics and volcanism
DE: 8164 Stresses: crust and lithosphere
SC: Tectonophysics [T]
MN: Fall Meeting 2005