HR: 0800h
AN: T41C-1209    [Abstracts]
TI: Rapid Kinematic and Tectonic Variations Along the 1400-km-long Australia-Woodlark Plate Boundary Zone, Papua New Guinea and Woodlark Basin
AU: * Mann, P
EM: paulm@ig.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Road, Austin, TX 78759 United States
AU: Taylor, F W
EM: fred@ig.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Road, Austin, TX 78759 United States
AU: Gahagan, L
EM: plates@ig.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Road, Austin, TX 78759 United States
AU: Watson, L
EM: lisaw@ig.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Road, Austin, TX 78759 United States
AB: Previous GPS studies have shown the wide variability in present-day plate motions across the highly arcuate, 1400-km-long Australia-Woodlark plate boundary extending from Papua New Guinea to the Solomon Islands. GPS-determined motions range from orthogonal oceanic spreading in the Woodlark basin, to continental transtension in the 2.5-km-high core complex area of easternmost Papua New Guinea, to continental strike-slip and transpression in 4-km-high mountains of the Papuan Peninsula. We use imagery, earthquake focal mechanisms, coral reef uplift data, and structural mapping studies to establish the along-strike continuity of the active plate boundary fault. Systematic angular changes in the direction of the plate vector along this continuous fault explain its varied tectonic geomorphology, Holocene uplift history, and geologic structure. We use a series of plate reconstructions to illustrate the longer term, Cenozoic evolution of this boundary including: its formation as an arcuate, N- and NE-dipping ophiolitic suture zone during Paleogene time, the progressive "unzippering" of this thrust over the past 6 Ma along a N- and NE-dipping, low-angle normal fault in easternmost Papua New Guinea, and its "zippering" or continued shortening on the suture thrust in the Owen Stanley Ranges of the Papuan Peninsula. Over the 1400-km-length of the fault, the length of segments of oceanic spreading, transtension, and transpression is 250-500 km; the time period separating one tectonic style from the succeeding style encroaching from the east is several million years. This systematic spatial and temporal superposition of tectonic styles, leads to complex - but predictable - along-strike variations in geologic history.
DE: 8158 Plate motions--present and recent (3040)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting