HR: 1340h
AN: B13A-0204    [Abstracts]
TI: How Lithospheric Stress Constrains Dike Intrusions in Mid-Ocean Ridges
AU: * Qin, R
EM: rqin@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 302B Oceanography 61 Rt. 9W, Palisades, NY 10964 United States
AU: Buck, R W
EM: buck@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 302B Oceanography 61 Rt. 9W, Palisades, NY 10964 United States
AB: It's believed that more than 90% of the spreading in mid-ocean ridges is accommodated by dike intrusions. Recent advances in ocean bottom observations makes feasible the direct measurement of seafloor displacement during dike intrusions, and will provide a tool to probe into the magmatic and faulting processes in mid-ocean ridges. Here we use numerical modeling to explore the effect of lithospheric stress on dike intrusions. We firstly calculate lithospheric stress prior to dike intrusion in mid-ocean ridges using visco-elastoplastic rheology and show that the distribution and magnitude of lithospheric stress are different for ridges with different spreading rate and thermal structure. Then we assume the stress state in the dike changes into lithostatic during dike intrusion, and numerically model the corresponding seafloor displacement and the variation of dike width along the depth. Also we show that lithospheric stress may determine the maximum depth of dike opening, and the bottom of the dike may be well below the magma chamber or even may penetrate down into the asthenosphere on the axis.
DE: 8414 Eruption mechanisms
DE: 8164 Stresses--crust and lithosphere
DE: 3035 Midocean ridge processes
DE: 3094 Instruments and techniques
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting