Sequence stratigraphy on an early Cretaceous passive margin, Exmouth Plateau
Permian-Jurassic rifting of northwestern Australia resulted in the development of a passive continental margin flanking the northeastern Indian Ocean. On this margin the relatively thin synrift to postrift sedimentary sequence of southern Exmouth Plateau was drilled during ODP Leg 122. A sequence-stratigraphy analysis of the complete Mesozoic-Cenozoic sedimentary succession at Sites 762 and 763 was derived from a synthesis of seismic stratigraphy, wireline logs, lithostratigraphy, biostratigraphy, and magnetostratigraphy. Results indicate that during breakup, the southern Exmouth Plateau was a transform margin with an extensional component. Between the Tithonian and Valanginian, a thick clastic wedge prograded from the transform margin south of Site 763 northwestward toward Site 762 and onto subsiding continental crust. Southern clastic supply decreased into the Aptian-Cenomanian, and cyclic deposition of deep-water mudstones continued during subsidence of the earlier shelf margin wedge. Between the Albian and Cenomanian, deposition gradually became dominated by pelagic carbonates. Two regional unconformities mark the Cenomanian/Turonian and Cretaceous/Tertiary boundaries. Each was an erosional event, succeeded by renewed pelagic carbonate deposition that began in the distal northern basin and onlapped progressively toward the topographic high, which persisted into the Tertiary along the southern margin. The entire Jurassic to Holocene record at the southern Exmouth Plateau ODP sites is less than 1500 m thick and represents a classic rift to mature ocean passive-margin succession.
- Research Organization:
- Dalhousie Univer., Halifax, Nova Scotia (Canada)
- OSTI ID:
- 6181219
- Report Number(s):
- CONF-890404-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Vol. 73:3; Conference: AAPG annual convention with DPA/EMD Divisions and SEPM, San Antonio, TX, USA, 23 Apr 1989
- Country of Publication:
- United States
- Language:
- English
Similar Records
Sedimentary basin framework of Exmouth Plateau, northwest Australia
Mesozoic evolution and exploration potential of the western Exmouth Plateau, Australia