Australian-Antarctic breakup and seafloor spreading: Balancing geological and geophysical constraints

Williams, S.; Whittaker, Joanne M.; Halpin, Jacqueline A.; Müller, R. Dietmar

doi:10.1016/j.earscirev.2018.10.011

Cited by 57 publications

(55 citation statements)

References 107 publications

(173 reference statements)

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“…The construction of deforming plate models for conjugate passive margins may often result in revisiting the fit and early opening history of a given margin pair to ensure that reconstructions are compliant with both geological and geophysical observations, which are complementary in the sense that geophysical data provide strong constraints for the tightness of the fit (via constraining the COB, UCCL, and crustal thickness of the rifted margin), while geological data are most useful in constraining the fit of conjugate margins along strike, for example, via matching geological features. How to build best fit models for conjugate passive margins by balancing these constraints is summarized in Williams et al ().…”

Section: Methodsmentioning

confidence: 99%

“…Many alternative models for the rifting and breakup history of this region have been published, putting emphasis on interpretations of different sets of regional geological or geophysical data. These models are evaluated in Williams et al (), illustrating why a balanced combination of geological and geophysical observations does not lead to reconstructions such as that by White et al (), which features an extant ocean basin between Australia and East Antarctica for much of the Mesozoic, for which there is no evidence. The central Indian Ocean plate deformation zone (Kreemer et al, ) is not included in our model as we are focused on deforming continental crust.…”

Section: Deforming Regions Within the Global Plate Modelmentioning

confidence: 99%

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A Global Plate Model Including Lithospheric Deformation Along Major Rifts and Orogens Since the Triassic

et al. 2019

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Global deep‐time plate motion models have traditionally followed a classical rigid plate approach, even though plate deformation is known to be significant. Here we present a global Mesozoic–Cenozoic deforming plate motion model that captures the progressive extension of all continental margins since the initiation of rifting within Pangea at ~240 Ma. The model also includes major failed continental rifts and compressional deformation along collision zones. The outlines and timing of regional deformation episodes are reconstructed from a wealth of published regional tectonic models and associated geological and geophysical data. We reconstruct absolute plate motions in a mantle reference frame with a joint global inversion using hot spot tracks for the last 80 million years and minimizing global trench migration velocities and net lithospheric rotation. In our optimized model, net rotation is consistently below 0.2°/Myr, and trench migration scatter is substantially reduced. Distributed plate deformation reaches a Mesozoic peak of 30 × 106 km2 in the Late Jurassic (~160–155 Ma), driven by a vast network of rift systems. After a mid‐Cretaceous drop in deformation, it reaches a high of 48 x 106 km2 in the Late Eocene (~35 Ma), driven by the progressive growth of plate collisions and the formation of new rift systems. About a third of the continental crustal area has been deformed since 240 Ma, partitioned roughly into 65% extension and 35% compression. This community plate model provides a framework for building detailed regional deforming plate networks and form a constraint for models of basin evolution and the plate‐mantle system.

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Section: Methodsmentioning

confidence: 99%

Section: Deforming Regions Within the Global Plate Modelmentioning

confidence: 99%

A Global Plate Model Including Lithospheric Deformation Along Major Rifts and Orogens Since the Triassic

et al. 2019

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“…The activation of Tasmantid Guyots in the region (Vogt & Conolly, 1971) add 10.1029/2019GC008182 Geochemistry, Geophysics, Geosystems to the tectonic complexity and specifically makes rapid deepening of tectonic blocks in the region implausible. Drifting between Tasmania and Antarctica commenced in the middle Eocene (~49 Ma; Williams et al, 2019). Ocean crust formation already generated a deep oceanographic conduit by that time and consequently gradual deepening of the conjugate margins is expected (Totterdell et al, 2000).…”

Section: Late Eocene Ocean Circulation Invigoration Preconditioned Anmentioning

confidence: 99%

Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full‐Scale Glaciation

Houben

Bijl

Sluijs

et al. 2019

Geochem Geophys Geosyst

210

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During the Eocene‐Oligocene Transition (EOT; 34–33.5 Ma), Antarctic ice sheets relatively rapidly expanded, leading to the first continent‐scale glaciation of the Cenozoic. Declining atmospheric CO2 concentrations and associated feedbacks have been invoked as underlying mechanisms, but the role of the quasi‐coeval opening of Southern Ocean gateways (Tasman Gateway and Drake Passage) and resulting changes in ocean circulation is as yet poorly understood. Definitive field evidence from EOT sedimentary successions from the Antarctic margin and the Southern Ocean is lacking, also because the few available sequences are often incomplete and poorly dated, hampering detailed paleoceanographic and paleoclimatic analysis. Here we use organic dinoflagellate cysts (dinocysts) to date and correlate critical Southern Ocean EOT successions. We demonstrate that widespread winnowed glauconite‐rich lithological units were deposited ubiquitously and simultaneously in relatively shallow‐marine environments at various Southern Ocean localities, starting in the late Eocene (~35.7 Ma). Based on organic biomarker paleothermometry and quantitative dinocyst distribution patterns, we analyze Southern Ocean paleoceanographic change across the EOT. We obtain strong indications for invigorated surface and bottom water circulation at sites affected by polar westward‐flowing wind‐driven currents, including a westward‐flowing Antarctic Countercurrent, starting at about 35.7 Ma. The mechanism for this oceanographic invigoration remains poorly understood. The circum‐Antarctic expression of the phenomenon suggests that, rather than triggered by tectonic deepening of the Tasman Gateway, progressive pre‐EOT atmospheric cooling played an important role. At localities affected by the Antarctic Countercurrent, sea surface productivity increased and simultaneously circum‐Antarctic surface waters cooled. We surmise that combined, these processes contributed to preconditioning the Antarctic continent for glaciation.

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“…However, the age of final breakup and first oceanic crust is currently debated (Williams et al, 2019). The presence of high-quality seismic reflection data enabled the architecture of the ultra-distal domains to be interpreted as formed by a wide zone of exhumed mantle (Sayers et al, 2001;Direen et al, 2011;Ball et al, 2013;Gillard et al, 2015).…”

Section: East Antarctica Rifted Margin Off Wilkes Landmentioning

confidence: 99%

The role of serpentinization and magmatism in the formation of decoupling interfaces at magma-poor rifted margins

Gillard

Tugend

Müntener

et al. 2019

Earth-Science Reviews

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In spite of recent progress in the understanding of magma-poor rifted margins, the processes leading to the formation and evolution of the exhumed mantle domain and its transition toward steady state oceanic crust remain debated. In particular, the parameters controlling the progressive localization of extensional deformation and magmatic processes leading to the formation of an oceanic spreading center are poorly understood. In this paper, we highlight the occurrence of two major decoupling horizons controlling the structural and magmatic evolution of distal magma-poor rifted margins. They are marked by strong seismic reflectors located at about 1 sec TWTT (Upper Reflectors-UR) and 2 sec TWTT (Lower Reflectors-LR) below top basement in domains of exhumed mantle at several magma-poor rifted margins. Both reflection seismic observations and studies on the physical properties of serpentinized mantle suggest that the UR likely results from deformation localized along a rheological interface at about 3 km below top basement, associated with an abrupt change in the mechanical behavior of peridotites once they are serpentinized to ~15%. We suggest that this interface played a major role in successive fault reorganizations during formation of the exhumed mantle domain. The comparison of reflection seismic observations with Alpine field analogues suggests that the LR likely results from an interaction between magmatism, deformation and hydration reactions during final rifting. Based on our results, we suggest that during final rifting the strain distribution is controlled first by hydration and then by magmatic processes in the domain of exhumed mantle.

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Australian-Antarctic breakup and seafloor spreading: Balancing geological and geophysical constraints

Cited by 57 publications

References 107 publications

A Global Plate Model Including Lithospheric Deformation Along Major Rifts and Orogens Since the Triassic

A Global Plate Model Including Lithospheric Deformation Along Major Rifts and Orogens Since the Triassic

Late Eocene Southern Ocean Cooling and Invigoration of Circulation Preconditioned Antarctica for Full‐Scale Glaciation

The role of serpentinization and magmatism in the formation of decoupling interfaces at magma-poor rifted margins

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