Otway Continental Margin Transect: Crustal architecture from wide‐angle seismic profiling across Australia's southern margin

Finlayson, D. M.; Lukaszyk, I.; Collins, C. D. N.; Chudyk, E.C.

doi:10.1080/08120099808728428

Cited by 5 publications

(5 citation statements)

References 37 publications

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“…Such breakup is commonly a result of massive transient heat input into the lithosphere, resulting in widespread thermal and volcanic effects (Coffin & Eldholm 1992). In contrast, lithospheric domains adjacent to the GAB margin, such as the Otway Basin (Finlayson et al 1998) and its conjugate Terre Adélie margin (Colwell et al 2006), show none of the attributes of volcanic breakup and attendant lithospheric weakening. Thus, the thermal impact of Valanginian-Hauterivian volcanic breakup proximal to the Naturaliste-Diamantina margin cannot yet be ruled out as a significant influence on the thermomechanical behaviour of crust at the free boundary during subsequent non-volcanic breakup later in the Cretaceous.…”

Section: Discussionmentioning

confidence: 99%

“…Current knowledge of the Australian side of the Southern Rift System (SRS) (Finlayson et al 1998;Sayers et al 2001;this study) indicates that at least the Australian flank of this system has compartments of non-volcanic rifting all along its length.…”

Section: Discussionmentioning

confidence: 99%

“…Farther east, in the Duntroon-Otway and Sorell basins, rifting kinematics became very oblique to the eastwest axis of spreading (Willcox 1990;Willcox & Stagg 1990). Sea-floor spreading magnetic anomalies are thus very difficult to recognize in this sector (Roots et al 1985;Finlayson et al 1998).…”

Section: Study Areamentioning

confidence: 99%

“…These are interpreted as stacked synrift lava flows, and intercalated volcaniclastics, as they show growth against the faults. These may be equivalents of the late Jurassic basaltic rocks of the Casterton Beds in the deep Otway Basin (Finlayson et al 1998) in the eastern part of the Southern Rift System. Basement and the rift section are unconformably overlain by post-rift sedimentary section up to 0.5 s (c. 0.5 km) thick that is characterized by highcontinuity, laminar reflections, typical of an open marine environment.…”

Section: Seismic Interpretationmentioning

confidence: 99%

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Nature of the continent–ocean transition zone along the southern Australian continental margin: a comparison of the Naturaliste Plateau, SW Australia, and the central Great Australian Bight sectors

Direen

Borissova

Stagg

et al. 2007

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We document the interpretation of three crustal sections from coincident deep seismic reflection, gravity and magnetic data acquired on Australia's southern margin: one section from the Naturaliste Plateau and the Diamantina Zone; and two in the Great Australian Bight (GAB). Interpretations are based on an integrated study of deep multichannel seismic, gravity and magnetic data, together with sparse sonobuoy and dredging information.All interpreted sections of the margin show a transition from thinned continental crust, through a wide continent ocean transition zone (COTZ). In the GAB the transition is to slow sea-floor spreading oceanic crust that dates from breakup in the Campanian (c. 83 Ma); in the Naturaliste-Diamantina margin the earliest oceanic crust is undated. The COTZ on these margins is geologically and geophysically complex, but interpretation of all data, including dredge hauls, is consistent with the presence of a mixture of modified continental lower crust, breakup related volcanics and exhumed continental mantle. Serpentinized detachment faults are not well imaged, but have been inferred from high-amplitude magnetic signatures interpreted to arise from magnetite associated with the hydration of peridotites. Alternative models for the structure of the COTZ, involving either mafic underplating or aborted sea-floor spreading, have been explored, but are considered unlikely on this margin.Similarity in the final architecture of these margins has major implications for the nature of rifting in the Southern Rift System, and may point to the entire 4000 km-long system being non-volcanic in character.Second-order differences in geometry and morphology of the two areas studied are unlikely to be a function of strain rate. Instead, they probably reflect complexities owing to the multiple tectonic events that occurred during final Gondwanide fragmentation. The most dramatic of these is the impact of hotspot activity in the Kerguelen Plateau, which commenced some 50 Ma prior to final breakup in that sector.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Seismic Interpretationmentioning

confidence: 99%

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Nature of the continent–ocean transition zone along the southern Australian continental margin: a comparison of the Naturaliste Plateau, SW Australia, and the central Great Australian Bight sectors

Direen

Borissova

Stagg

et al. 2007

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“…The Gambier Basin, previously the Gambier Embayment of the Otway Basin, forms the western part of the Australian Southern Rift System, itself formed by Jurassic–Cenozoic rifting and spreading between the Australian and Antarctic plates (Stagg et al 1990; O’Brien et al 1994; Hill et al 1995; Finlayson et al 1998). It stretches southeast along the southeast coast of South Australia to the Dartmoor Ridge in western Victoria (Figure 1).…”

Section: Regional Geologymentioning

confidence: 99%

Sequences and biofacies packages in the mid‐Cenozoic Gambier Limestone, South Australia: Reappraisal of foraminiferal evidence

Li¹,

McGowran²,

White³

2000

Australian Journal of Earth Sciences

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The mid to outer neritic carbonates of the Gambier Limestone (Upper Eocene to lower Middle Miocene) can be divided into seven units by using criteria of sequence stratigraphy and foraminiferal biofacies. The boundaries fall mainly on erosional surfaces, even though the temporal duration of these surfaces appears to be largely beyond the resolution of foraminiferal biostratigraphy. The Eocene/Oligocene contact is distinctively unconformable in several sections, with at least part of the Upper Eocene sediments missing. Chert nodules, common to abundant in most sections, are associated with deep-or cool-water benthic assemblages (> 100-200 m and < 15°C), indicating cool, nutrient-rich bottom conditions probably influenced by the Antarctic Circumpolar Current beginning during the Early Oligocene. The mid-Oligocene fall in sea-level was probably coupled with a major local uplift that removed at least part of the Lower Oligocene, an event widely recorded in the Australian-New Zealand region. In areas weakly affected, this glacioeustatic lowstand is represented by chert-free limestone and grey to pink dolomites in some sections, with a poorly preserved assemblage comprising few planktonic and deep-water benthic species. Local unconformities separate regional unconformity-bounded or allostratigraphic packages of strata to represent third-order sequences. Although variations in local subsidence might have influenced accumulation space and sediment thickness, glacioeustatic influence on the packaging of the sequences and units of the Gambier Limestone was easily the more effective and concordant with the global patterns.

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The Structure of the Continental Margin off Wilkes Land and Terre Adélie Coast, East Antarctica

et al.

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Otway Continental Margin Transect: Crustal architecture from wide‐angle seismic profiling across Australia's southern margin

Cited by 5 publications

References 37 publications

Nature of the continent–ocean transition zone along the southern Australian continental margin: a comparison of the Naturaliste Plateau, SW Australia, and the central Great Australian Bight sectors

Nature of the continent–ocean transition zone along the southern Australian continental margin: a comparison of the Naturaliste Plateau, SW Australia, and the central Great Australian Bight sectors

Sequences and biofacies packages in the mid‐Cenozoic Gambier Limestone, South Australia: Reappraisal of foraminiferal evidence

The Structure of the Continental Margin off Wilkes Land and Terre Adélie Coast, East Antarctica

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