Peter Betts | Monash University (original) (raw)

Papers by Peter Betts

Research paper thumbnail of Crustal evolution and geodynamic setting of the Sefwi Greenstone Belt, WAC

Crustal evolution and geodynamic setting of the Sefwi Greenstone Belt, WAC. The Palaeoproterozoic... more Crustal evolution and geodynamic setting of the Sefwi Greenstone Belt, WAC. The Palaeoproterozoic West African Craton (2.25 - 2.07 Ga) represents one of the youngest, large provinces of juvenile crust on Earth. It displays lithological and architectural similarities to a numberof late Archean Provinces, including the Abitibi-Opatica terrane, Superior Province and Karelian and Kola cratons of the Fennoscandian Shield. Forming just after the Archean-Palaeoproterozoic transition, the magmatic evolution and geodynamic setting of juvenile crust formation of the WAC continues to stimulate scientific debate.

Research paper thumbnail of Congested subduction in New Zealand driving plate boundary reogranisation and accretion

AGU Fall Meeting Abstracts, Dec 1, 2017

Research paper thumbnail of The 1800–1100Ma tectonic evolution of Australia

Precambrian Research, Jan 20, 2006

This paper presents a plate tectonic model for the evolution of the Australian continent between ... more This paper presents a plate tectonic model for the evolution of the Australian continent between ca. 1800 and 1100 Ma. Between ca. 1800 and 1600 Ma episodic orogenesis occurred along the southern margin of the continent above a north-dipping subduction system. During ...

Research paper thumbnail of A Potential Field Approach to Defining Major Lithospheric Structures along the Margin of the West Australian Craton

ASEG extended abstracts, Dec 1, 2010

Research paper thumbnail of Reinterpretation of the tectonic context of high-temperature metamorphism in the Broken Hill Block, NSW, and implications on the Palaeo- to Meso-Proterozoic evolution

Precambrian Research, Oct 1, 2008

The origin of high temperatures during regional low-pressure granulite facies metamorphism within... more The origin of high temperatures during regional low-pressure granulite facies metamorphism within the Proterozoic Broken Hill Block, Australia, has been reinterpreted to be the result of burial of anomalously hot rock packages for which the lithospheric geothermal gradient was initially elevated during early rifting ca. 1.71-1.67 Ga, and then maintained during a ca. 1.62 Ga short-lived mid-crustal extensional event. Mid-crustal extension at ca. 1.62 Ga was associated with amphibolite facies metamorphism and elevated lithospheric geothermal gradients, and occurred prior to activity along D2 high-temperature shear zones, peak low-pressure granulite facies metamorphism (ca. 1.60 Ga) and crustal shortening during the Olarian Orogeny (ca. 1.60-1.59 Ga). This reinterpretation places the Broken Hill Block within an environment in which multiple episodes of transient extension (ca. 1.71-1.62 Ga) were followed by a switch to shortening at ca. 1.60 Ga. The interpreted tectonic environment is a continental back-arc setting located in the overriding plate of a subduction zone along the southern margin of Palaeoproterozoic Australia.

Research paper thumbnail of The effects of inward and outward dipping craton margin geometry on upper crustal deformation: Insights from analogue modelling

Craton margins undergo intense deformation influenced by the pre-existing crustal and lithospheri... more Craton margins undergo intense deformation influenced by the pre-existing crustal and lithospheric architecture, rheology, and far-field kinematics. The role of rheological contrasts and weak zones at the edge of the craton has been discussed, but it is unclear whether deformation in the upper crust is influenced by the geometry of the craton margin itself (i.e., whether the margin dips towards or away from the interior of the craton). Our analogue experiments are aimed at studying the influence of craton margin geometry on structures formed during rifting and inversion, as craton margins are prone to reworking and reactivation during superimposed tectonic events.The experiments are designed based on the geometries of the eastern and southern margins of the North Australian Craton which has experienced multiple stages of extension and shortening. The inward vs. outward dipping craton margins in these areas were interpreted from crustal-scale seismic reflection data. In our experime...

Research paper thumbnail of Australia Nuna and Beyond

Research paper thumbnail of Ordovician-Late Silurian geodynamics of north Queensland

Palaeozoic continental growth and accretionary tectonism along the eastern margin of Gondwana is ... more Palaeozoic continental growth and accretionary tectonism along the eastern margin of Gondwana is characterised by the inversion of back-arc basins and accretion of the magmatic arc terranes and micro-continental ribbons.

Research paper thumbnail of Ribbon Tectonics: Ordovician to Silurian evolution of North Queensland

Research paper thumbnail of Tectonic switches during the Palaeo-Mesoproterozoic transition implications for mineral systems

Research paper thumbnail of Spatial analysis of an intra-plate basaltic volcanic field in a compressional tectonic setting: South-eastern Australia

Journal of Volcanology and Geothermal Research, 2017

The Newer Volcanics Province (NVP) is a Pliocene to Recent intra-plate basaltic volcanic field (B... more The Newer Volcanics Province (NVP) is a Pliocene to Recent intra-plate basaltic volcanic field (BVF) that has formed in a compressive tectonic setting (σ v <σ hmin <σ Hmax) and is not readily attributed to a single geodynamic process. A comprehensive spatial analysis of both monogenetic eruption centres and coeval vents of the NVP constrain factors that control the distribution and emplacement of volcanoes. A point-set of 434 eruption centres totalling 726 vents are divided into three geographical sub-provinces for analysis. Kernel density estimation and Poisson nearest neighbour analysis are used

Research paper thumbnail of Dynamics of continental accretion

Nature, 2014

Subduction zones become congested when they try to consume buoyant, exotic crust. The accretionar... more Subduction zones become congested when they try to consume buoyant, exotic crust. The accretionary mountain belts (orogens) that form at these convergent plate margins have been the principal sites of lateral continental growth through Earth&amp;amp;#39;s history. Modern examples of accretionary margins are the North American Cordilleras and southwest Pacific subduction zones. The geologic record contains abundant accretionary orogens, such as the Tasmanides, along the eastern margin of the supercontinent Gondwana, and the Altaïdes, which formed on the southern margin of Laurasia. In modern and ancient examples of long-lived accretionary orogens, the overriding plate is subjected to episodes of crustal extension and back-arc basin development, often related to subduction rollback and transient episodes of orogenesis and crustal shortening, coincident with accretion of exotic crust. Here we present three-dimensional dynamic models that show how accretionary margins evolve from the initial collision, through a period of plate margin instability, to re-establishment of a stable convergent margin. The models illustrate how significant curvature of the orogenic system develops, as well as the mechanism for tectonic escape of the back-arc region. The complexity of the morphology and the evolution of the system are caused by lateral rollback of a tightly arcuate trench migrating parallel to the plate boundary and orthogonally to the convergence direction. We find geological and geophysical evidence for this process in the Tasmanides of eastern Australia, and infer that this is a recurrent and global phenomenon.

Research paper thumbnail of Geophysical and volcanological insights into the subsurface morphology and eruptive histories of complex maar volcanoes within the Newer Volcanics Province, Western Victoria

ASEG Extended Abstracts, 2013

Research paper thumbnail of Assessing uncertainty in the integration of aeromagnetic data and structural observations in the Deering Hills region of the Musgrave Province

Australian Journal of Earth Sciences, 2008

... 08120090802266600 ARA Aitken a * , PG Betts a , BF Schaefer a &amp;amp; SE Rye a pages 11... more ... 08120090802266600 ARA Aitken a * , PG Betts a , BF Schaefer a &amp;amp; SE Rye a pages 1127-1138. ... Evolution of a crustal scale transpressive shear zone in the Albany–Fraser Orogen, SW Australia: 1. P–T conditions of Mesoproterozoic metamorphism in the Coramup Gneiss. ...

Research paper thumbnail of Formation of ore deposits triggered by aseismic ridge subduction

Magmatic-hydrothermal ore deposits in suprasubduction environments are abundant in the Andes, whe... more Magmatic-hydrothermal ore deposits in suprasubduction environments are abundant in the Andes, where they are associated with the eastward subduction of the Nazca plate beneath the continental South American plate during the last 200 Ma. These deposits do not seem to correspond with progressive subduction processes but are concentrated at distinct regions that experienced pulses of intense metallogenic activity. An example is the Miocene metallogenic belt in the central Andes that was formed during a relatively short period between 15-5 Ma, and is characterised by clusters of mineral deposits in northern Peru and in central Chile. We propose that a key factor for the occurrence of metallogenic episodes during progressive subduction is related to bathymetric heterogeneities within the subducting oceanic plate. Such heterogeneities are manifested by the subduction of topographic anomalies that affected the whole dynamics of the subduction system and triggered metallogenic processes. Our study shows that the spatial and temporal distribution of Miocene ore deposits in the Peruvian Andes correspond with the arrival of relatively buoyant topographic anomalies, namely the Nazca Ridge in central Peru and the now-consumed Inca Plateau in northern Peru, at the subduction zone. Plate reconstruction shows a rapid metallogenic response to the arrival of the topographic anomalies at the subduction trench. This is indicated by clusters of ore deposits situated within the proximity of the laterally migrating zones of ridge subduction. It is accordingly suggested that tectonic changes associated with aseismic ridge subduction, (i.e. a change in the state of stress, flattening of the subducting slab, temporal quiescence in the volcanic activity and partial melting of the subducting slab) may trigger the formation of ore deposits in metallogenically fertile suprasubduction environments.

Research paper thumbnail of The ca. 1740–1710 Ma Leichhardt Event: Inversion of a continental rift and revision of the tectonic evolution of the North Australian Craton

Precambrian Research, 2017

Interpretation and modelling of high resolution regional geophysical data of the central Leichhar... more Interpretation and modelling of high resolution regional geophysical data of the central Leichhardt River Fault Trough in the Mount Isa Inlier are used to determine the timing of a major basin inversion event following the development of the ca 1780-1740 Ma Leichhardt Superbasin. Inversion of the Leichhardt Superbasin formed the regional north-south trending Leichhardt Anticline during east-west shortening. The limbs of the anticline are overprinted by several eastwest trending wedge-shaped, non-magnetic sub-basins filled with ca 1710 Ma Calvert and Isa superbasin successions. These relationships suggest inversion of the Leichhardt Superbasin occurred between ca 1740 and 1710 Ma. The event is also known to have affected the northern and eastern North Australian Craton. The scale of the inversion suggests it was a significant event that we have defined as the Leichhardt Event. This event requires a major tectonic driver to the east of the North Australian Craton, possibly the accretion of a micro-continental ribbon to the east of the Mount Isa Inlier. The results of this study have implication for paleogeographic reconstruction of the Australian continent during the formation of Nuna because eastern North Australian Craton faced an ocean at ca 1740-1720 Ma. The results also challenge the significance and intensity of crustal shortening associated with the ca 1600-1500 Ma Isan Orogeny throughout the western Mount Isa Inlier.

Research paper thumbnail of Crustal boundaries of the marginal terranes of the northern Gawler Craton

Research paper thumbnail of Geological Uncertainty and Geophysical Ambiguity: Friends or Foes?

Research paper thumbnail of Geodynamics of oceanic plateau and plume head accretion and their role in Phanerozoic orogenic systems of China

Geoscience Frontiers, 2015

We present three 3D numerical models of deep subduction where buoyant material from an oceanic pl... more We present three 3D numerical models of deep subduction where buoyant material from an oceanic plateau and a plume interact with the overriding plate to assess the influence on subduction dynamics, trench geometry, and mechanisms for plateau accretion and continental growth. Transient instabilities of the convergent margin are produced, resulting in: contorted trench geometry; trench migration parallel with the plate margin; folding of the subducting slab and orocline development at the convergent margin; and transfer of the plateau to the overriding plate. The presence of plume material beneath the oceanic plateau causes flat subduction above the plume, resulting in a "bowed" shaped subducting slab. In plateau-only models, plateau accretion at the edge of the overriding plate results in trench migration around the edge of the plateau before subduction is re-established directly behind the trailing edge of the plateau. The plateau shortens and some plateau material subducts. The presence of buoyant plume material beneath the oceanic plateau has a profound influence on the behaviour of the convergent margin. In the plateau þ plume model, plateau accretion causes rapid trench advance. Plate convergence is accommodated by shearing at the base of the plateau and shortening in the overriding plate. The trench migrates around the edge of the plateau and subduction is re-established well behind the trailing edge of the plateau, effectively embedding the plateau into the overriding plate. A slab window forms beneath the accreted plateau and plume material is transferred from the subducting plate to the overriding plate through the window. In all of the models, the subduction zone maintains a relatively stable configuration away from the buoyancy anomalies within the downgoing plate. The models provide a dynamic context for plateau and plume accretion in Phanerozoic accretionary orogenic systems such as the East China Orogen and the Central Asian Orogen (Altiads), which are characterised by accreted ophiolite complexes with diverse geochemical affinities, and a protracted evolution of accretion of exotic terranes including oceanic plateau and terranes with plume origins.

Research paper thumbnail of Mesoproterozoic plume-modified orogenesis in eastern Precambrian Australia

Tectonics, 2009

Tectonic models for the latest Paleoproterozoic to earliest Mesoproterozoic evolution of eastern ... more Tectonic models for the latest Paleoproterozoic to earliest Mesoproterozoic evolution of eastern Australia (circa 1620–1500 Ma) are diverse and either emphasize plume or plate margin activity, neither of which satisfactorily explains all geological observations. The dichotomy ...

Research paper thumbnail of Crustal evolution and geodynamic setting of the Sefwi Greenstone Belt, WAC

Crustal evolution and geodynamic setting of the Sefwi Greenstone Belt, WAC. The Palaeoproterozoic... more Crustal evolution and geodynamic setting of the Sefwi Greenstone Belt, WAC. The Palaeoproterozoic West African Craton (2.25 - 2.07 Ga) represents one of the youngest, large provinces of juvenile crust on Earth. It displays lithological and architectural similarities to a numberof late Archean Provinces, including the Abitibi-Opatica terrane, Superior Province and Karelian and Kola cratons of the Fennoscandian Shield. Forming just after the Archean-Palaeoproterozoic transition, the magmatic evolution and geodynamic setting of juvenile crust formation of the WAC continues to stimulate scientific debate.

Research paper thumbnail of Congested subduction in New Zealand driving plate boundary reogranisation and accretion

AGU Fall Meeting Abstracts, Dec 1, 2017

Research paper thumbnail of The 1800–1100Ma tectonic evolution of Australia

Precambrian Research, Jan 20, 2006

This paper presents a plate tectonic model for the evolution of the Australian continent between ... more This paper presents a plate tectonic model for the evolution of the Australian continent between ca. 1800 and 1100 Ma. Between ca. 1800 and 1600 Ma episodic orogenesis occurred along the southern margin of the continent above a north-dipping subduction system. During ...

Research paper thumbnail of A Potential Field Approach to Defining Major Lithospheric Structures along the Margin of the West Australian Craton

ASEG extended abstracts, Dec 1, 2010

Research paper thumbnail of Reinterpretation of the tectonic context of high-temperature metamorphism in the Broken Hill Block, NSW, and implications on the Palaeo- to Meso-Proterozoic evolution

Precambrian Research, Oct 1, 2008

The origin of high temperatures during regional low-pressure granulite facies metamorphism within... more The origin of high temperatures during regional low-pressure granulite facies metamorphism within the Proterozoic Broken Hill Block, Australia, has been reinterpreted to be the result of burial of anomalously hot rock packages for which the lithospheric geothermal gradient was initially elevated during early rifting ca. 1.71-1.67 Ga, and then maintained during a ca. 1.62 Ga short-lived mid-crustal extensional event. Mid-crustal extension at ca. 1.62 Ga was associated with amphibolite facies metamorphism and elevated lithospheric geothermal gradients, and occurred prior to activity along D2 high-temperature shear zones, peak low-pressure granulite facies metamorphism (ca. 1.60 Ga) and crustal shortening during the Olarian Orogeny (ca. 1.60-1.59 Ga). This reinterpretation places the Broken Hill Block within an environment in which multiple episodes of transient extension (ca. 1.71-1.62 Ga) were followed by a switch to shortening at ca. 1.60 Ga. The interpreted tectonic environment is a continental back-arc setting located in the overriding plate of a subduction zone along the southern margin of Palaeoproterozoic Australia.

Research paper thumbnail of The effects of inward and outward dipping craton margin geometry on upper crustal deformation: Insights from analogue modelling

Craton margins undergo intense deformation influenced by the pre-existing crustal and lithospheri... more Craton margins undergo intense deformation influenced by the pre-existing crustal and lithospheric architecture, rheology, and far-field kinematics. The role of rheological contrasts and weak zones at the edge of the craton has been discussed, but it is unclear whether deformation in the upper crust is influenced by the geometry of the craton margin itself (i.e., whether the margin dips towards or away from the interior of the craton). Our analogue experiments are aimed at studying the influence of craton margin geometry on structures formed during rifting and inversion, as craton margins are prone to reworking and reactivation during superimposed tectonic events.The experiments are designed based on the geometries of the eastern and southern margins of the North Australian Craton which has experienced multiple stages of extension and shortening. The inward vs. outward dipping craton margins in these areas were interpreted from crustal-scale seismic reflection data. In our experime...

Research paper thumbnail of Australia Nuna and Beyond

Research paper thumbnail of Ordovician-Late Silurian geodynamics of north Queensland

Palaeozoic continental growth and accretionary tectonism along the eastern margin of Gondwana is ... more Palaeozoic continental growth and accretionary tectonism along the eastern margin of Gondwana is characterised by the inversion of back-arc basins and accretion of the magmatic arc terranes and micro-continental ribbons.

Research paper thumbnail of Ribbon Tectonics: Ordovician to Silurian evolution of North Queensland

Research paper thumbnail of Tectonic switches during the Palaeo-Mesoproterozoic transition implications for mineral systems

Research paper thumbnail of Spatial analysis of an intra-plate basaltic volcanic field in a compressional tectonic setting: South-eastern Australia

Journal of Volcanology and Geothermal Research, 2017

The Newer Volcanics Province (NVP) is a Pliocene to Recent intra-plate basaltic volcanic field (B... more The Newer Volcanics Province (NVP) is a Pliocene to Recent intra-plate basaltic volcanic field (BVF) that has formed in a compressive tectonic setting (σ v <σ hmin <σ Hmax) and is not readily attributed to a single geodynamic process. A comprehensive spatial analysis of both monogenetic eruption centres and coeval vents of the NVP constrain factors that control the distribution and emplacement of volcanoes. A point-set of 434 eruption centres totalling 726 vents are divided into three geographical sub-provinces for analysis. Kernel density estimation and Poisson nearest neighbour analysis are used

Research paper thumbnail of Dynamics of continental accretion

Nature, 2014

Subduction zones become congested when they try to consume buoyant, exotic crust. The accretionar... more Subduction zones become congested when they try to consume buoyant, exotic crust. The accretionary mountain belts (orogens) that form at these convergent plate margins have been the principal sites of lateral continental growth through Earth&amp;amp;#39;s history. Modern examples of accretionary margins are the North American Cordilleras and southwest Pacific subduction zones. The geologic record contains abundant accretionary orogens, such as the Tasmanides, along the eastern margin of the supercontinent Gondwana, and the Altaïdes, which formed on the southern margin of Laurasia. In modern and ancient examples of long-lived accretionary orogens, the overriding plate is subjected to episodes of crustal extension and back-arc basin development, often related to subduction rollback and transient episodes of orogenesis and crustal shortening, coincident with accretion of exotic crust. Here we present three-dimensional dynamic models that show how accretionary margins evolve from the initial collision, through a period of plate margin instability, to re-establishment of a stable convergent margin. The models illustrate how significant curvature of the orogenic system develops, as well as the mechanism for tectonic escape of the back-arc region. The complexity of the morphology and the evolution of the system are caused by lateral rollback of a tightly arcuate trench migrating parallel to the plate boundary and orthogonally to the convergence direction. We find geological and geophysical evidence for this process in the Tasmanides of eastern Australia, and infer that this is a recurrent and global phenomenon.

Research paper thumbnail of Geophysical and volcanological insights into the subsurface morphology and eruptive histories of complex maar volcanoes within the Newer Volcanics Province, Western Victoria

ASEG Extended Abstracts, 2013

Research paper thumbnail of Assessing uncertainty in the integration of aeromagnetic data and structural observations in the Deering Hills region of the Musgrave Province

Australian Journal of Earth Sciences, 2008

... 08120090802266600 ARA Aitken a * , PG Betts a , BF Schaefer a &amp;amp; SE Rye a pages 11... more ... 08120090802266600 ARA Aitken a * , PG Betts a , BF Schaefer a &amp;amp; SE Rye a pages 1127-1138. ... Evolution of a crustal scale transpressive shear zone in the Albany–Fraser Orogen, SW Australia: 1. P–T conditions of Mesoproterozoic metamorphism in the Coramup Gneiss. ...

Research paper thumbnail of Formation of ore deposits triggered by aseismic ridge subduction

Magmatic-hydrothermal ore deposits in suprasubduction environments are abundant in the Andes, whe... more Magmatic-hydrothermal ore deposits in suprasubduction environments are abundant in the Andes, where they are associated with the eastward subduction of the Nazca plate beneath the continental South American plate during the last 200 Ma. These deposits do not seem to correspond with progressive subduction processes but are concentrated at distinct regions that experienced pulses of intense metallogenic activity. An example is the Miocene metallogenic belt in the central Andes that was formed during a relatively short period between 15-5 Ma, and is characterised by clusters of mineral deposits in northern Peru and in central Chile. We propose that a key factor for the occurrence of metallogenic episodes during progressive subduction is related to bathymetric heterogeneities within the subducting oceanic plate. Such heterogeneities are manifested by the subduction of topographic anomalies that affected the whole dynamics of the subduction system and triggered metallogenic processes. Our study shows that the spatial and temporal distribution of Miocene ore deposits in the Peruvian Andes correspond with the arrival of relatively buoyant topographic anomalies, namely the Nazca Ridge in central Peru and the now-consumed Inca Plateau in northern Peru, at the subduction zone. Plate reconstruction shows a rapid metallogenic response to the arrival of the topographic anomalies at the subduction trench. This is indicated by clusters of ore deposits situated within the proximity of the laterally migrating zones of ridge subduction. It is accordingly suggested that tectonic changes associated with aseismic ridge subduction, (i.e. a change in the state of stress, flattening of the subducting slab, temporal quiescence in the volcanic activity and partial melting of the subducting slab) may trigger the formation of ore deposits in metallogenically fertile suprasubduction environments.

Research paper thumbnail of The ca. 1740–1710 Ma Leichhardt Event: Inversion of a continental rift and revision of the tectonic evolution of the North Australian Craton

Precambrian Research, 2017

Interpretation and modelling of high resolution regional geophysical data of the central Leichhar... more Interpretation and modelling of high resolution regional geophysical data of the central Leichhardt River Fault Trough in the Mount Isa Inlier are used to determine the timing of a major basin inversion event following the development of the ca 1780-1740 Ma Leichhardt Superbasin. Inversion of the Leichhardt Superbasin formed the regional north-south trending Leichhardt Anticline during east-west shortening. The limbs of the anticline are overprinted by several eastwest trending wedge-shaped, non-magnetic sub-basins filled with ca 1710 Ma Calvert and Isa superbasin successions. These relationships suggest inversion of the Leichhardt Superbasin occurred between ca 1740 and 1710 Ma. The event is also known to have affected the northern and eastern North Australian Craton. The scale of the inversion suggests it was a significant event that we have defined as the Leichhardt Event. This event requires a major tectonic driver to the east of the North Australian Craton, possibly the accretion of a micro-continental ribbon to the east of the Mount Isa Inlier. The results of this study have implication for paleogeographic reconstruction of the Australian continent during the formation of Nuna because eastern North Australian Craton faced an ocean at ca 1740-1720 Ma. The results also challenge the significance and intensity of crustal shortening associated with the ca 1600-1500 Ma Isan Orogeny throughout the western Mount Isa Inlier.

Research paper thumbnail of Crustal boundaries of the marginal terranes of the northern Gawler Craton

Research paper thumbnail of Geological Uncertainty and Geophysical Ambiguity: Friends or Foes?

Research paper thumbnail of Geodynamics of oceanic plateau and plume head accretion and their role in Phanerozoic orogenic systems of China

Geoscience Frontiers, 2015

We present three 3D numerical models of deep subduction where buoyant material from an oceanic pl... more We present three 3D numerical models of deep subduction where buoyant material from an oceanic plateau and a plume interact with the overriding plate to assess the influence on subduction dynamics, trench geometry, and mechanisms for plateau accretion and continental growth. Transient instabilities of the convergent margin are produced, resulting in: contorted trench geometry; trench migration parallel with the plate margin; folding of the subducting slab and orocline development at the convergent margin; and transfer of the plateau to the overriding plate. The presence of plume material beneath the oceanic plateau causes flat subduction above the plume, resulting in a "bowed" shaped subducting slab. In plateau-only models, plateau accretion at the edge of the overriding plate results in trench migration around the edge of the plateau before subduction is re-established directly behind the trailing edge of the plateau. The plateau shortens and some plateau material subducts. The presence of buoyant plume material beneath the oceanic plateau has a profound influence on the behaviour of the convergent margin. In the plateau þ plume model, plateau accretion causes rapid trench advance. Plate convergence is accommodated by shearing at the base of the plateau and shortening in the overriding plate. The trench migrates around the edge of the plateau and subduction is re-established well behind the trailing edge of the plateau, effectively embedding the plateau into the overriding plate. A slab window forms beneath the accreted plateau and plume material is transferred from the subducting plate to the overriding plate through the window. In all of the models, the subduction zone maintains a relatively stable configuration away from the buoyancy anomalies within the downgoing plate. The models provide a dynamic context for plateau and plume accretion in Phanerozoic accretionary orogenic systems such as the East China Orogen and the Central Asian Orogen (Altiads), which are characterised by accreted ophiolite complexes with diverse geochemical affinities, and a protracted evolution of accretion of exotic terranes including oceanic plateau and terranes with plume origins.

Research paper thumbnail of Mesoproterozoic plume-modified orogenesis in eastern Precambrian Australia

Tectonics, 2009

Tectonic models for the latest Paleoproterozoic to earliest Mesoproterozoic evolution of eastern ... more Tectonic models for the latest Paleoproterozoic to earliest Mesoproterozoic evolution of eastern Australia (circa 1620–1500 Ma) are diverse and either emphasize plume or plate margin activity, neither of which satisfactorily explains all geological observations. The dichotomy ...