The response of a basin‐scale Miocene barrier reef system to long‐term, strong subsidence on a passive continental margin, Barcoo Sub‐basin, Australian North West Shelf

Abstract

The Miocene sedimentary succession of the southern Browse Basin records the response of a tropical reef system to long‐term, strong subsidence on a passive continental margin. Geological interpretation of a comprehensive two‐dimensional (2D) seismic reflectivity data set documents for the first time the development of a continuous Miocene barrier reef on the Australian North West Shelf. With a length of over 250 km, this barrier reef is among the Earth's largest in the Neogene record. A sequence stratigraphic analysis tied to well data shows that the main controls for the evolution, growth and demise of the reef system were subsidence, third‐order global‐scale eustatic variations and antecedent topography. The generally very high Miocene subsidence rates estimated for the study area cannot be explained by typical passive‐margin subsidence controlled by lithospheric cooling and sedimentary loading alone. Additional dynamic subsidence induced by mantle convection, though documented as unusually large on the northern margin of Australia during the Neogene, can be also regarded as being of only minor importance. Therefore, accelerated tectonic subsidence related to the collision of the Australian and Eurasian Plates 250–500 km north of the study area seems to exert an important influence on reef development and demise, complicated by local tectonic inversion. The Miocene tectonic reactivation and inversion of an older structural grain is interpreted to have controlled the reef development considerably by providing localized topographic highs along transpressional anticlines above basement‐rooted faults that served as preferential sites for reef growth and retreat during times of rapidly rising sea level. This exemplarily shows that the far‐field effects of collision‐induced tectonic subsidence can significantly influence carbonate systems on passive margins.

Pinnacle features at the base of isolated carbonate buildups marking point sources of fluid offshore Northwest Australia

“…While no other faults offset the Miocene sequence, it is noted that subseismicscale fractures and faults may be present and control fluid flow. In addi tion, late Miocene inversion is documented in the southern Browse Basin (RosleffSoerensen et al, 2016).…”

“…Jurassic continental rifting between Greater India and Western Australia (Veevers and Cot teril, 1978;Langhi and Borel, 2008;Rosleff Soerensen et al, 2012) generated north easttrending structures on the North West Shelf, including in the Yampi, Leveque, Caswell, and Barcoo subbasins ( Fig. 1; Longley et al, 2002;Langhi and Borel, 2008;RosleffSoerensen et al, 2012RosleffSoerensen et al, , 2016Howarth and Alves, 2016). Early Cretaceous subsidence and the deposition of a passivemargin sequence buried the riftrelated topography (Fig.…”

Satellite‐ and field‐based facies mapping of isolated carbonate platforms from the Kepulauan Seribu Complex, Indonesia

“…Carbonate deposition is often dominated by bioclastic assemblages, few nonskeletal grains and a notable absence of coated grains (Jordan, Wharton, & Cook, ; Lees & Buller, ; Scrutton, , ; Wilson, ). The small, isolated carbonate platforms forming the islands of the Kepulauan Seribu Complex therefore provide a useful modern analogue for buried carbonate systems in Indonesia (Park et al., ; Wilson, ) and other similar Cenozoic carbonates from Southeast Asia and northern Australia (Belde, Back, Bourget, & Reuning, ; Morgan, George, Harris, Kupecz, & Sarg, ; Rosleff‐Soerensen, Reuning, Back, & Kukla, , ). Sediment distribution patterns form the fundamental studies on sediment formation, redeposition, sediment dynamics and early diagenesis in modern reefs and carbonate platforms (Gischler, ; Gischler, Isaack, & Hudson, ).…”

Adding the missing third and fourth dimensions to trajectory analysis in carbonate systems

“…This far‐field tectonic activity could have triggered northward‐increasing differential subsidence and accommodation increase in the Browse Basin (Rosleff‐Soerensen, Reuning, Back, & Kukla, ), likely causing the observed progradation decrease in the NW of our profile and a resulting shift in average shelf break strike direction from 62° in SB4 to 55° in SB12. Similarly, Rosleff‐Soerensen et al () analysed the variability in progradation and retrogradation of the Miocene reef complexes in the Browse Basin along a 180 km transect and attributed decreased progradation towards the NW of their study area to increased accommodation from local inversion tectonics related to the collision of Australia with the Timor plate. Another example of large‐scale tectonic forcing of a sedimentary system with resulting differential progradation comes from the Santos Basin, Brazil; Madof et al () identified a geometrical hinge that caused a shift in the average shelf break strike direction of the fluvio‐deltaic Marambaia Formation (from 32° to 28°, and then back to 35° within ~6 Myr during the Ypresian) through an eastward shift in accommodation creation and sediment accumulation, which Cobbold, Meisling, and Mount () interpreted to be caused by differential tectonic deformation related to hinterland uplift and stream capture as control on eastward migration of the source area during this time.…”

“…Inversion tectonics, related to the Miocene-Pliocene Timor Trough collision zone ~500 km north of the Browse Basin, was a significant far-field tectonic forcing factor in the vicinity of the study area (Hall, 2011;Kennard, Deighton, Ryan, Edwards, & Boreham, 2003). This farfield tectonic activity could have triggered northwardincreasing differential subsidence and accommodation increase in the Browse Basin (Rosleff-Soerensen, Reuning, Back, & Kukla, 2016), likely causing the observed progradation decrease in the NW of our profile and a resulting shift in average shelf break strike direction from 62° in SB4 to 55° in SB12. Similarly, Rosleff-Soerensen et al (2016) analysed the variability in progradation and retrogradation of the Miocene reef complexes in the Browse Basin along a 180 km transect and attributed decreased progradation towards the NW of their study area to increased accommodation from local inversion tectonics related to the collision of Australia with the Timor plate.…”