--> Abstract: Sequence Analysis of Late Devonian-Early Carboniferous Reef and Ramp Carbonates, Canning Basin, Australia, by J. M. Kennard, P. N. Southgate, M. J. Jackson, P. E. O'Brien, and M. J. Sexton; #91012 (1992).

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ABSTRACT: Sequence Analysis of Late Devonian-Early Carboniferous Reef and Ramp Carbonates, Canning Basin, Australia

KENNARD, JOHN M., PETER N. SOUTHGATE, M. JIM JACKSON, PHIL E. O'BRIEN, and MIKE J. SEXTON, Bureau of Mineral Resources, Canberra, Australia

Integrated sequence analysis of seismic and well data provides a new understanding of the subsurface and exposed reef complexes of the Canning basin and enables the construction of a detailed relative sea level curve for Late Devonian-Early Carboniferous time. Sixteen carbonate sequences have been mapped and two distinct phases of sedimentation recognized: a Givetian-Famennian reef-rimmed platform complex, and a Famennian-Tournaisian ramp complex.

The reef complex consists of two cycles of progressively onlapping sequences which are separated by a major basinward shift of facies. Five sequences within the lower cycle display successively backstepping highstand platform margins, whereas three sequences within the upper cycle display successively advancing margins; these cycles correlate with the previously identified Pillara and Nullara cycles. Each reef sequence is characterized by marked reciprocal sedimentation; lowstand clastic-rich sediments (basin floor fan, slope fan, and prograding complex) in the basin, and transgressive and highstand platform carbonates on the adjacent shelf.

The ramp complex comprises six successively offlapping sequences, overlain by two progressively onlapping sequences. Each sequence comprises a lowstand clastic prograding complex, and a thin, laterally extensive, mixed carbonate-clastic highstand with a poorly defined shelf-slope break. Lowstand fans are absent in all but the basal ramp sequences in which slope fans are poorly developed.

The sequences have a duration of about 1-2 Ma, and record third-order relative sea level cycles. The Pillara and Nullara reef cycles record a longer second-order cycle, and the ramp complex encompasses a successive second-order cycle. The lowstand event separating the Pillara and Nullara cycles is of Late Frasnian age, and the Frasnian-Famennian boundary occurs within transgressive deposits of the basal sequence of the Nullara cycle.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)