HR: 10:35h
AN: T11E-02 INVITED     [PDF]
TI: The Rifting-to-Spreading Transition in the Woodlark Basin
AU: * Taylor, B
EM: taylorb@hawaii.edu
AF: SOEST, University of Hawaii, 1680 East-West Rd., Honolulu, 96822 United States
AU: Goodliffe, A M
EM: amg@hawaii.edu
AF: SOEST, University of Hawaii, 1680 East-West Rd., Honolulu, 96822 United States
AU: Martinez, F
EM: fernando@hawaii.edu
AF: SOEST, University of Hawaii, 1680 East-West Rd., Honolulu, 96822 United States
AB: The Woodlark Basin-Papuan Peninsula region exemplifies a continuum of active extensional processes, laterally varying from continental rifting to seafloor spreading at 2-6 cm/yr. There, we have previously shown that continental breakup proceeds by successive phases of rifting localization, spreading center nucleation, spreading center propagation (sometimes stalling), and then an en echelon offset to the next site of localized rifting. The breakup has been centered within thickened orogenic crust that includes a Neogene volcanic arc west of 153E built on Paleocene ophiolite, resulting in a first order asymmetry between the stratigraphy and structure of the conjugate margins (forearc and backarc). The rifted margins are about 100 km wide and the transition from stretched continental to oceanic crust is very sharp (less than 5 km wide). Using swath bathymetry, magnetization and seismic reflection data, we illustrate the breakup of conjugate margins of varying ages (3.2, 1.9, 0.8, and 0 Ma) and involving multiple generations of normal faults (both high- and low-angle). Rifting continues for up to 1 m.y. after seafloor spreading initiates. Ridge jumps produced multiple ocean/continent boundaries within one transect. ODP-calibrated margin subsidence data reveal that focused faulting is accompanied by more regional lower crustal flow prior to breakup.
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 8105 Continental margins and sedimentary basins
SC: Tectonophysics [T]
MN: 2003 Fall Meeting