A SEQUENCE STRATIGRAPHIC DEPOSITIONAL MODEL OF NEOPROTEROZOIC STRATA, YOWALGA AREA, OFFICER BASIN,WESTERN AUSTRALIA

Abstract

Additional data and further studies have now improved geological, geophysical, and geochemical understanding of the Neoproterozoic strata of the Officer Basin. New sequence stratigraphic analysis of continuously cored drillholes (particularly Empress–1/1A), extended throughout the area with wireline log and seismic correlations, provide enhanced recognition of depositional fades and thus basin architecture. Four major flooding events and fifteen sedimentary successions, interpreted as parasequence sets by regional correlation, are recognised across the Yowalga area. These parasequence sets are traceable using seismic data, with flooding events identified on cores and logs producing regional or local reflectors with good amplitude and continuity.

Sedimen tary cycles are dominantly mixed carbonates- siliciclastics with primarily progradational stacking patterns. These imply transgressive and regressive cycles in a basin with low bathymetric relief. Depositional settings range from supratidal to just below storm wave base.

This interpretation improves the prediction of potential petroleum systems. An architectural model for each formation allows prediction of depositional trends including potential reservoir, source rock and seal in the Yowalga area.