HR: 15:10h
AN: T43D-07 INVITED     [Abstracts]
TI: Upper Crustal Deformation in Onshore Exposures of the Tj”rnes Fracture Zone, Northern Iceland
AU: * Karson, J A
EM: jkarson@duke.edu
AF: Division of Earth $&$ Ocean Sciences, Duke University, Durham, NC 27708-0230 United States
AU: Brandsd\'{o}ttir, B
EM: bryndis@raunvis.hi.is
AF: Institute of Earth Sciences, University of Iceland Sturlugata 7, Reykjavik, 107 Iceland
AU: S$\ae$mundsson, K
EM: ks@isor.is
AF: Iceland GeoSurvey, Grens\'{a}svegur 9, Reykjavik, 108 Iceland
AB: The Tj”rnes Fracture Zone (TFZ) links the northern rift zone (NRZ) of Iceland with the Kolbeinsey Ridge to the north. The TFZ formed 7 Ma ago as a result of an eastward jump of the spreading axis in northern Iceland. Northward propagation of the NRZ has resulted in a northward migration of the locus of transform-related deformation. Active deformation occurs in a swath 150 km long (EW) and 50 km wide (NS) involving a complex array of right-lateral (WNW) strike-slip and oblique-slip faults bounding several (NS) rifts. Previously published and new structural data from the onshore portions of the TFZ reveal pervasive fracturing and alteration, rotation of spreading-related structures, and re-activation of NS faults in a bookshelf-faulting deformational style. These structures are cut by major WNW-trending, intensely shattered, dextral, strike-slip fault zones. Enigmatic WNW-trending dikes cut NNE-trending, spreading-related features and pre-date recent TFZ deformation. In some places, late NW-trending oblique-slip faults cut this entire structural assemblage. Strike-slip faulting and reactivation of older spreading structures affects the crust over a width of at least 10 km onshore and several tens of kilometers offshore. These data support interpretations of the offshore parts of the plate boundary and may provide an analog for deformation along migrating ridge-ridge transform faults elsewhere on the mid-ocean ridge system.
DE: 8010 Fractures and faults
DE: 8100 TECTONOPHYSICS
DE: 8150 Plate boundary--general (3040)
DE: 3035 Midocean ridge processes
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting