Timing of Deposition and Geochemistry of Source Rocks in the Georgina Basin, Australia

• Author / Creator

  Miles, Naomi E

• This study characterized two organic-rich source rock formations from three
  different sub-basins of the Georgina Basin, Central Australia, using the 187Re – 187Os
  isotope system and a suite of major, minor, and trace elements. The major organic-rich
  source rock in the Georgina Basin, the lower section of the middle to late Cambrian
  Arthur Creek Formation, overlies two minor source rocks, the middle Cambrian Hay
  River and Thorntonia Limestone Formations. Two major sub-basins, the Toko Syncline
  and the Dulcie Syncline in the southern Georgina Basin, controlled many aspects of
  sedimentation, organic matter accumulation and hydrocarbon generation. The Arthur
  Creek Formation was deposited in both sub-basins, but at different times, according to
  the trilobite record. The ages of the Arthur Creek and Thorntonia Limestone Formations
  are currently defined based on specific trilobite species from the Central Australian
  Trilobite Zonation. Biostratigraphy in the Georgina Basin tied to the Central Australian
  Trilobite Zonation identified specific species of trilobites that are similar to globally
  recognized trilobites with isotopically defined ages. In the Dulcie Syncline, the Arthur
  Creek Formation was deposited between ~509 and 501 Ma, whereas in the Toko Syncline
  the ages were from ~503 to 498 Ma based on ages from the biostratigraphic record.
  Farther to the north, in the Undilla sub-basin, the Thorntonia Limestone deposited
  synchronously with the Dulcie Syncline Arthur Creek Formation between ~508 and 505
  Ma.
  Based on the 187Re – 187Os isotopic ages determined in this study, the ages of the
  Arthur Creek Formation in both sub-basins are younger than the biostratigraphically
  determined ages. In the Dulcie Syncline, the Arthur Creek Formation Re-Os age is 481 ±
  ii
  10 Ma. The Toko Syncline Arthur Creek Formation is 477.5 ± 9.5 Ma. The trace element
  suites were able to characterize specific paleoenvironments, controlled by basin
  geometry, during deposition of the Arthur Creek and Thorntonia Limestone Formation.
  In the Dulcie Syncline, the trace element profiles indicate deposition in a heavily
  restricted basin.
  Trace element abundances in the Arthur Creek Formation of the Toko Syncline
  show a progression from severe restriction towards a better-circulated sub-basin.
  Towards the top of the Arthur Creek Formation, marginal regions of the Toko Syncline
  experienced regular oxidation but deeper regions of the basin did not experience any
  oxidation. The Thorntonia Limestone Formation showed signs of regular oxidation,
  possibly seasonally related. Rock-eval data for both formations indicated that the Arthur
  Creek and Thorntonia Limestone Formations reached the oil window.

• Subjects / Keywords

  • Australia
  • Geomorphology

• Graduation date

  Fall 2015

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R34J0B322

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.