ABSTRACT: Geologic History of the Southeast Argo Abyssal Plain, Northwest Australia

BUFFLER, RICHARD T., University of Texas at Austin, Austin, TX

The drilling results from ODP Site 765 and a regional ODP seismic line between Sites 765 and 261 allow a new interpretation of the seismic stratigraphy and geologic history of the southeastern Argo Abyssal Plain. An excellent tie between the seismic data and the drilling results was made using a composite of velocity information determined from core measurements, sonobuoys, a VSP experiment, and MCS data. The top of Late Jurassic oceanic crust forms an irregular, faulted acoustic basement. It is overlain by an acoustically transparent Lower Cretaceous claystone that is uniformly thick across the area, although it locally thins and onlaps the top of oceanic crust. Very large basement highs correspond with the trace of major northwest trending oceanic fracture zones previously identifie by magnetic anomaly studies. Cut and fill features (moats) adjacent to these basement highs indicate strong bottom currents during the Cretaceous.

A regionally continuous, high-amplitude reflection package corresponds to a Late Cretaceous-early Tertiary period of sediment starvation interspersed with turbidite deposition. Early Tertiary uplift and faulting of the northern part of the area indicates regional mid-place deformation that may be related to initiation of subduction along the Java trench to the north. This uplifted area is progressively onlapped to the north by a thick section of Miocene and younger carbonate turbidites and debris flows that filled the southeastern Argo basin through major canyon systems cutting the adjacent margins of the Scott and Exmouth plateaus.

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)