GEOLOGY Mining –

Bulletin (Geological Survey of Western Australia) ;

• 310 p. : ill., maps ; 24 cm. + maps (10 fold col. maps; 27 cm.).

  • Bibliography: p.284-299.

  #160526 (prev ownership name)

• • Western Australia. Perth region. Geological features. Reports, surveys
  • Geology — Western Australia — Perth Region
  • The Perth Basin is a \(172,300\text{ km}^2\) north-trending sedimentary basin extending 1,300 km along Western Australia’s coast. Formed by Paleozoic to Mesozoic rifting, it holds up to 15 km of sediment, containing major commercial gas discoveries, particularly in the northern Permian and Triassic sequences. The basin separates from the Yilgarn Craton along the Darling Fault. 
    Key Geological Features:
    • • Structure: A complex, elongated rift basin (onshore and offshore) formed during the separation of Australia and Greater India. Key tectonic units include the Dandaragan and Bunbury Troughs, and the Vlaming Sub-basin.
      • Stratigraphy: Sedimentation ranges from Silurian to Quaternary, with major Mesozoic sequences.
        • • Permian/Triassic: Key reservoir rocks (e.g., in the northern Perth Basin).
          • Jurassic: Comprises significant units such as the Cattamarra Coal Measures and Yarragadee Formation.
          • Cretaceous/Cenozoic: Features marine sediments, the Bunbury Basalt, and superficial coastal sands and limestone.

    • Hydrocarbons: Significant gas production, particularly in the northern area (e.g., [Waitsia], [West Erregulla] fields).
    • Groundwater: Contains substantial groundwater resources. 
    Tectonic Evolution:
    1. 1. Permian Extension: Initial rift formation along the western Yilgarn Craton.
       2. Triassic-Jurassic Rifting: Major tectonic activity during the separation of India and Australia.
       3. Early Cretaceous Breakup: A regional unconformity formed (the “Breakup Unconformity”).
       4. Passive Margin: Post-early Cretaceous, the basin matured into a passive margin. 

    Geological Significance:
    The northern Perth Basin is highly active for energy exploration, while the southern part is characterized by thick, less explored sediments. The basin’s structure is dominated by the Darling Fault to the east and a series of offshore faults that parallel the coast.