Eocene Calcareous Nannofossil Biostratigraphy of the Otway Basin, Australia

A sequence of biostratigraphic events spanning the middle to late Eocene was deduced from calcareous nannofossil assemblages in four sections of southeastern Australia's Otway Basin. The study compares this sequence with its counterpart in New Zealand and aligns it with tropical planktic foraminiferal zones, revising the placement of key foraminiferid events. Marine ingressions during the middle Eocene were diachronous across the basin, coinciding with a major change in sea-floor spreading rates south of Australia.

Use Cases

• Correlating Eocene biostratigraphic events between Australia and New Zealand based on the described fossil sequences.
• Analyzing diachroneity in Eocene marine sedimentation across the Otway Basin based on the described transgressive rock units and fossil assemblages.
• Revising planktic foraminiferal zone assignments for species like Acarinina primitiva based on the comparison with nannofossil biostratigraphy.
• Investigating the relationship between sea-floor spreading rates and marine ingressions in the middle Eocene as suggested in the description.

Strengths

• Data spans a defined geological interval from the lowest appearance of Cyclicargolithus reticulatus to the disappearance of Discoaster saipanensis.
• Findings are placed against the planktic foraminiferal P. zones of the tropics, providing a standardized chronological framework.
• Analysis is based on four studied sections within the Otway Basin, offering multiple geographic data points.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.
• Data may reflect geographic/temporal bias inherent to data_gov_au.

Provenance

Source

Australian Ocean Data Network

Collection Method

Study of middle to late Eocene calcareous nannofossil assemblages from four sections.

Time Range

Middle Eocene to latest Eocene

Freshness

Last updated 2026-06-04 10:15:11.756138; freshness should be verified.

Geography

Otway Basin, southeastern Australia; Gambier Embayment and Browns Creek area