Rowley Sub-basin, Roebuck Basin, Release Areas W10-3, W10-4 ...

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eleAse AreA geology local tectonic setting the Rowley sub-basin is a major westward-thickening upper Paleozoic–mesozoic depocentre situated on the outer continental shelf (Figure 3) where it covers an area of approximately 65000 km 2 . it contains about 9 km of Permo-carboniferous or older strata and up to 6 km of mesozoic–Holocene sediments (Figure 4; smith et al, 1999). structurally, the sub-basin is separated from the beagle sub-basin of the northern carnarvon basin to the southwest by the north turtle Hinge Zone and thouin Graben, and from the bedout and Oobagooma sub-basins by the bedout High and Oobagooma High. the Paleozoic and lower mesozoic succession within the Rowley subbasin onlaps the broome Platform, bedout High and Oobagooma High (Figure 3). these sediments thicken seaward and are terminated at the present continent–ocean boundary by large rift faults (Figure 5). structural evolution and depositional History of the sub-basin the development of the Rowley sub-basin is largely inferred from what is known of the geological evolution of the adjacent bedout sub-basin and canning basin (lipski, 1993; Kennard et al, 1994; smith et al, 1999). An early, Ordovician–early carboniferous section, equivalent to the succession occurring in the canning basin, has been postulated to underlie the Rowley sub-basin (lipski, 1993), but it is not evident on seismic data and has not been intersected in wells. the late carboniferous– cenozoic structural and depositional history of the Rowley sub-basin has been divided into several phases. Late Carboniferous–Permian the end of the carboniferous was a transition from northeast to southwest extension in the region. during the initial portion of this transition a failed rift arm trending north-northwest to southsoutheast developed between the beagle and Rowely sub-basin associated with the separation of the sibumasu terrane from Gondwana (metcalfe, 1988; smith et al, 1999). subsequently, southeast – to east-southeast-oriented asymmetric half graben developed in the Rowley sub-basin, accumulating thick glacio-fluvial and shallow marine deposits of the Grant Group (Figure 4), overlain by nonglaciogenic marine and fluvio-deltaic clastics (Poole sandstone, noonkanbah formation, liveringa Group; Kennard et al, 1994). this phase of basin deposition was interrupted by the regional uplift and volcanism of the bedout movement (Figure 5; colwell and stagg, 1994). triassiC–earLy JurassiC in the triassic, a period of thermal subsidence following the bedout movement, resulted in regional transgressive marine and fluvio-deltaic sedimentation (locker shale, Keraudren and bedout formations; lipski 1993, 1994). this period was punctuated by several northwest–southeast transpressional events (fitzroy movements; smith et al, 1999). 1. fitzroy movement i (ladinian) was responsible for fault reactivation and the development of large transpressional ‘flower structures’ along the north turtle Hinge Zone; 2. fitzroy movement ii (norian) drove minor folding and rift shoulder uplift within the Rowely subbasin; and 3. fitzroy movement iii (sinemurian) marked a major change in gross stratal geometries within the Roebuck basin, from the predominantly back-stepping bedout formation to the prograding and aggrading depuch formation. Geology of Release Areas W10-3, W10-4, W10-5, and W10-6 | www.petroleum-acreage.gov.au 2
earLy JurassiC–earLy CretaCeous following the fitzroy movement, fluvio-deltaic and associated marine sediments of the lower– middle Jurassic depuch formation prograded to the west and northwest infilling the sub-basin during a period of relatively slow thermal subsidence (Figure 6). the top of the depuch formation is a major unconformity developed during callovian breakup and associated regional uplift that marked the end of active rifting in areas adjacent to the Roebuck basin (Figure 7; lipski, 1993). subsequent thermal relaxation promoted rapid transgression and accumulation of condensed marine mudstones (baleine and Egret formations). An influx of siliciclastic sediment (broome sandstone) occurred with uplift of the sediment source in the Valanginian, when Greater india moved away from the western margin of Australia (smith, 1999; smith et al, 1999). earLy CretaCeous–HoLoCene thermal relaxation of the crust soon after the Valanginian allowed for passive-margin accumulation of a condensed interval of marine mudstones and marls (mermaid and nelson Rocks formations; Woodside Energy limited, 2001). subsequently marls and limestones accumulation developed across much of the north West shelf including the upper cretaceous toolonga caliliutite and an extensive carbonate wedge that prograded through much of the Paleogene (lipski, 1993; Woodside Energy limited, 2001), in the late miocene, collision of the indo-Australia and Eurasia plates led to a regional unconformity, and transtensional wrenching along the footwalls of the northeast–southwest oriented half-graben structures in the Rowley sub-basin. subsequently, passive margin deposition of marine mudstone and carbonates resumed and persists to the present day (lipski, 1993). Geology of Release Areas W10-3, W10-4, W10-5, and W10-6 | www.petroleum-acreage.gov.au 3
Page 1 and 2: Image: Woodside Energy Ltd. AustrAl
Page 3: geologicAl inFormAtion releAse AreA
Page 7 and 8: PHoenix 1 (1980) Phoenix 1 was dril
Page 9 and 10: seismic coverage seismic surveys in
Page 11 and 12: potential reservoirs in the Rowley
Page 13 and 14: MAP SHEET SD 50 MAP SHEET SE 50 (Ro
Page 15 and 16: Release Area W10-4 Rowley Sub-basin
Page 17 and 18: 1783 1784 1785 1851 1852 1853 1854
Page 19 and 20: Permian Triassic Jurassic Cretaceou
Page 21 and 22: Two-way time (s) 0 2 4 6 8 NW SE Li
Page 23 and 24: System Quaternary Paleogene Neogene

Rowley Sub-basin, Roebuck Basin, Release Areas W10-3, W10-4 ...

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