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Late Triassic conodont and palynomorph biostratigraphy and conodont thermal maturation, North West Shelf, Australia

Created 16/10/2025

Updated 16/10/2025

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Late Triassic (Norian-Rhaetian) conodonts recovered from borecores and sea-bottom dredge samples on the North West Shelf off Western Australia are assigned to the Metapolygnathus primitius, Epigondolella triangularis, E. spiculata, E. postera, E. bidentata, Misikella hernsteini, and M. posthernsteini Zones. Based on previous studies, particularly from North America, these conodont zones can be used to tie with the standard Triassic ammonite zonation. The present record therefore provides the first set of chronologie anchor points for dating the co-occurring dinocyst assemblages and spore-pollen floras from the North West Shelf. Our conodont data show that the Hebecysta (al. Heibergella) balmei, Rhaetogonyaulax (al. Shublikodinium) wigginsii, and Wanneria (al. Suessia) listeri dinocyst zones are younger than suggested previously, and that some zonal ranges overlap. We conclude that further detailed palynological and conodont studies are urgently needed to resolve these problems and extend conodont age control into the early Late Triassic (Carnian) and the Middle Triassic. Key wells investigated include Ashmore Reef 1, Mt. Ashmore 1B, and Sahul Shoals 1. Conodont thermai maturation data indicate a very low thermal gradient on the Ashmore Platform near the shelf margin, but a more normal thermal gradient on the Sahul Platform and a high heat flow in the onshore Bonaparte Basin.

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Field Value
Title Late Triassic conodont and palynomorph biostratigraphy and conodont thermal maturation, North West Shelf, Australia
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/db6aaf7f-9de2-4c06-972f-967bc76554b7
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
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      [
        109.0,
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      [
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    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Late Triassic conodont and palynomorph biostratigraphy and conodont thermal maturation, North West Shelf, Australia". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/late-triassic-conodont-and-palynomorph-biostratigraphy-and-conodont-thermal-maturation-north-we