Middle Miocene– Pliocene siliciclastic influx across a carbonate shelf and influence of deltaic sedimentation on shelf construction, Northern Carnarvon Basin, Northwest Shelf of Australia

• Published in: Basin Research
• Main Authors: Sanchez, Carla M., Fulthorpe, Craig S., Steel, Ronald J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2012
• Subjects: Ice Sheet
• Online Access: http://dx.doi.org/10.1111/j.1365-2117.2012.00546.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2117.2012.00546.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2117.2012.00546.x

Abstract Middle M iocene to P liocene siliciclastics of the B are F ormation represent a long‐lived ( ca . 11 Myr) break in the otherwise carbonate‐dominated shelf of the N orthern C arnarvon B asin, N orthwest S helf of A ustralia. The quartz‐sandstone interval is correlated with the appearance of spectacular clinoform sets mapped on 3D and dense 2D seismic data. Twenty‐seven clinoform sets are interpreted as delta lobes primarily based on their plan‐view morphology (strike‐elongate to lobate features) and their 40–100‐m‐high clinoform amplitudes. The delta lobes were deposited on outer‐shelf to shelf‐edge positions, and the older deltas show evidence of a higher degree wave reworking than the younger deltas. Measurements of the along‐strike (migration) and down‐dip (progradation) movement of these deltas are compared with relative sea‐level behaviour inferred from shelf‐edge trajectory analysis. Delta lobes exhibit greater lateral shifting during relative sea‐level rise, whereas delta lobes are more restricted to dip‐oriented fairways during sea‐level fall, although no major incised valleys have been identified. Long‐term (cumulative) progradation of this delta system and subsequent backstepping correlates with long‐term sea‐level fall and rise during the late middle and late M iocene. In addition, a long‐term northeastward migration trend for these delta lobes was likely a result of localized uplift of an inversion anticline in the R osemary– L egendre T rend; the growth of this anticline probably steered the fluvial source for the delta system towards the northeast. The B are F ormation siliciclastic influx correlates with other middle M iocene increases in siliciclastic sediment supply worldwide. Global cooling and a shift to more arid conditions, negatively influencing vegetation cover, may have combined with more seasonally variable rainfall to generate the high sediment supply that built the deltas. Retreat of the siliciclastics could correlate with ice‐sheet growth in the N orthern H emisphere and/or ...