Australian Tertiary Marine Bed Age Revisions and Stratigraphic Data

Recent years have seen significant revisions in the estimated age of marine Tertiary deposits across Australia. The dataset documents these changes, including the recognition of Eocene deposits in southeastern Australia and the reclassification of beds from Oligocene to Eocene based on microfossil evidence like the genus Hantkenina. It is provided by the Australian Ocean Data Network and was last updated in April 2026.

Use Cases

• Reclassifying stratigraphic stages (e.g., Janjukian Stage, Anglesean Stage) based on the presence of index fossils like Hantkenina.
• Analyzing the vertical sequence and thickness of deposits, such as the over 4,000 feet of Middle Eocene beds identified in boreholes.
• Comparing age interpretations for specific formations, such as calcareous sandstones in the Adelaide Basin, to resolve debates between Lower, Middle, or Upper Pliocene classifications.
• Investigating the spatial distribution of Eocene, Oligocene, and Miocene deposits across regions like southwestern Victoria and South Australia.
• Studying the evidence for or against the existence of marine Oligocene beds in Australia as discussed in the textual data.

Strengths

• Documents specific, evidence-driven age revisions for multiple named geological stages and locations.
• References concrete stratigraphic evidence, including microfossil discoveries (Hantkenina) and borehole data proving over 4,000 feet of Middle Eocene strata.
• Covers a broad geographical scope within Australia, including southeastern Australia, Victoria, and the Adelaide Basin in South Australia.

Limitations

• The core data is presented as narrative text in HTML/PDF formats, lacking a structured, queryable tabular format with defined rows and columns.
• Sample data and specific row counts are unavailable, making quantitative analysis of the underlying observations impossible.
• The description focuses on historical reinterpretations, so the raw primary data (e.g., fossil counts, precise borehole measurements) may not be directly included.

Provenance

Source

Australian Ocean Data Network.

Collection Method

Compiled from published geological research, detailed mapping, and microfossil investigations.

Time Range

Focuses on the Tertiary period (Paleocene to Pliocene epochs), with analysis and revisions occurring in recent years.

Freshness

The record was last updated in April 2026, indicating recent maintenance.

Geography

Australia, with specific mentions of southeastern Australia, southwestern Victoria (Torquay, Anglesea), and the Adelaide Basin in South Australia.