Ocean Drilling Program; Leg 180 scientific prospectus; Woodlark Basin

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Author(s): Huchon, Philippe; Taylor, Brian; Klaus, Adam
Author Affiliation(s): Primary:
Ecole Normale Supérieure, Laboratoire de Géology, Paris, France
University of Hawaii, United States
Ocean Drilling Program, United States
Source: Scientific Prospectus, Vol.180, 64p. Publisher: Ocean Drilling Program, Texas A&M University, College Station, TX, United States. ISSN: 1058-1448
Note: In English. The reports in this series become obsolete after a cruise sails and will not be distributed. 61 refs.Scientific Prospectus No. 80
Summary: The lateral variation from active continental rifting to seafloor spreading within a small region makes the western Woodlark Basin an attractive area to investigate the mechanics of lithospheric extension. Earthquake source parameters and seismic reflection data indicate that low-angle (∼25° to 30°) normal faulting is active in the region of incipient continental separation. A low-angle normal fault emerges along the northern flank of Moresby Seamount, a continental crustal block with greenschist metamorphic basement. Asymmetric basement fault blocks overlain by only minor ponded sediments characterize the margin to the south, whereas the margin to the north has a down flexed prerift sedimentary basin and basement sequence unconformably onlapped by synrift sediments. Leg 180 will drill a transect of three sites just ahead of the spreading tip: ACE-9a on the down flexed northern margin; ACE-8a through the rift basin sediments, the low-angle normal fault zone, and into the footwall; and ACE-3c near the crest of the footwall fault block (Moresby Seamount). The primary objectives at these sites are (1) to characterize the composition and in situ properties (stress, permeability, temperature, pressure, physical properties, and fluid pressure) of an active low-angle normal fault zone to understand how such faults slip, and (2) to determine the vertical motion history of both the downflexed hanging wall and the unloaded footwall as local groundtruth for input into regional models to determine the timing and amount of extension prior to spreading initiation.
Year of Publication: 1998
Research Program: ODP Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; Coral Sea; Cores; Crust; Earthquakes; Faults; Geophysical methods; Geophysical profiles; Geophysical surveys; Leg 180; Lithosphere; Metamorphic rocks; Ocean Drilling Program; Ocean floors; Oceanic crust; Pacific Ocean; Plate tectonics; Rifting; Sea-floor spreading; Seismic methods; Seismic profiles; Solomon Sea; South Pacific; Southwest Pacific; Surveys; West Pacific; Woodlark Basin
Coordinates: S095200 S091100 E1513800 E1513200
Record ID: 2007086552
Copyright Information: GeoRef, Copyright 2018 American Geosciences Institute.