New evidence of Tasmania's tectonic history from a novel seismic experiment

Rawlinson, Nicholas; Houseman, G. A.; Collins, C. D. N.; Drummond, B. J.

doi:10.1029/2001gl013342

Cited by 25 publications

(33 citation statements)

References 10 publications

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“…recorded by an in-line array of sources and receivers), although recent studies (Zelt & Barton, 1998;Zelt et al, 1999;Day et al, 2001;Rawlinson et al, 2001b;Zelt et al, 2001) indicate that 3-D wide-angle surveys are becoming more frequent. In 2-D experiments, data coverage is often quite dense, and tomographic-style interpretation techniques are usually designed to allow both interface structure and layer velocities to be constrained by the data.…”

Section: Wide-angle Tomographymentioning

confidence: 99%

“…This consisted of the crust and the upper mantle separated by a Moho of variable depth. Lateral variations of velocity within the crust were not included because P n and P m P arrivals poorly Figure 33: χ 2 misfit versus iteration number for the inversion (using = 1.0) of P n and P m P traveltimes done by Rawlinson et al (2001b) for the Moho structure of Tasmania.…”

Section: Wide-angle Tomographymentioning

confidence: 99%

“…31), which includes an underplated low velocity lens, was successfully reconstructed from a starting model with only 2-D structure. Rawlinson et al (2001b) applied the method of Rawlinson et al (2001a) to wide-angle data collected as part of the TASGO project. In this study, an array of 44 land-based recorders was distributed throughout the island state of Tasmania, SE Australia, to record seismic energy from an encircling array of marine normal incidence reflection shot lines.…”

Section: Wide-angle Tomographymentioning

confidence: 99%

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Seismic Traveltime Tomography of the Crust and Lithosphere

Rawlinson

Sambridge

2003

Advances in Geophysics

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197

171

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Section: Wide-angle Tomographymentioning

confidence: 99%

Section: Wide-angle Tomographymentioning

confidence: 99%

Section: Wide-angle Tomographymentioning

confidence: 99%

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Seismic Traveltime Tomography of the Crust and Lithosphere

Rawlinson

Sambridge

2003

Advances in Geophysics

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197

171

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“…2002. The structure lies between a down-warp of the mantle (Moho) under the West Tasmania terrane (Rawlinson et al 2001) and a change in basement lithosphere under the East Tasmanian terrane (Kennett et al 2004), but has no direct expression in the underlying lithosphere imaged by Rawlinson & Kennett (2006). The Moho lies between 29 km and 32 km below the Tamar Trough and shallows towards Bass Strait (Clitheroe et al 2000).…”

Section: Trough Structurementioning

confidence: 99%

The Tamar Trough revisited: correlations berween sedimentary beds, basalts, their ages and valley evolution, North Tasmania

F.L¹,

Graham²,

Forsyth³

et al. 2006

PPRST

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The Tamar Trough, an Early Palaeogene fault structure, contains sedimentary beds and interleaved basaltic fl ows that infi ll the structure along its 70 km length. These infi lls represent a complex interplay between sedimentation, channel erosion, eruptive dislocations, and even 'out of trough' diyersions of the ancestral Tamar drainage. Several areas of resistant basalt fl ows remain in the south, upper, middle and lower Tamar reaches. Although some palynological control was known, radiometric dating of previously untested basalts now allows close integration and age-pegging for observed palynological biozones. The K-Ar and Ar-Ar ages of the basalt bodies indicate eruptive events at 47, 33-37 and 25 Ma, correlating with Proteacidites asperopo!us-Ma!vacipo!!is diversus, Nothofagites asperus and I'roteacidites tu bercu!atus biozone age sedimentary beds respectively. Basanite, alkali basalt and hawaiite fl ows dominate basalt lithology with lesser olivine nephelinite, transitional olivine basalt, olivine tholeiite and quartz tholeiite. Basalt geochemistry suggests derivation from different degrees of partial mantle melting (from 7 to 35%), with alkaline and tholeiitic basalts being derived from separate source regions. Most alkaline basalts have high-µ (HIMU) related trace element signatures, which are absent in the tholeiitic rocks. A basalt plug on the trough margin at Loira gave a Jurassic age and has Jura%ic dolerite-like geochemistry. The Tamar sequence suggests that the initial fl uvio-lacustrine and later channel-fi ll sedimentation from 65(?) to 24(?) Ma was then punctuated in places by periods of alkaline volcanism between 47 to 33(?) Ma, and alkaline and tholeiitic volcanism between 33 to 24(?) Ma. No Neogene fossils are known, so this later period was probably one of net erosion. These contrasting quiet sedimentary and more volcanic intervals are related here to a tectonic model that involves northerly drift of Victorian and Tasmanian lithosphere over several former Tasman metasomatised mantle plume sources.

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“…The paper integrates the Table Cape vent xenolith data with Boat Harbour (Sutherland et al 1996) and provides a revised lithospheric framework for the Wynyard-Boat Harbour region. The proposed lithology is then correlated with new seismic data on crust-mantle structures under northern Tasmania (Rawlinson et al 2001(Rawlinson et al , 2004.…”

Section: Introductionmentioning

confidence: 99%

Table Cape vent xenolith suite, northwest Tasmania: Mineralogy and implications for crust-mantle lithology and Miocene geotherms in Tasmania

F.L¹,

Raynor²,

Pogson³

2005

PPRST

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The Miocene Table Cape vent erupted a diverse mantle-crust xenolith suite within its fractionated nephclinitic matrix. Assemblages include mantle metaperidotites, garnet-metawebsterites and rarer garnet-metadinopyroxcnites, garnet-metawehrlires, metawcbstetites and crustal two-pyroxene granulites. Most metapyroxenites and granulites represent the Ti-Al-bearing augite suite and their bulk geochemistry indicates transitional olivine basalt magmatic affinities. Metasomatised, hydrous lithologies are only rarely present. Co-existing pyroxenes in the xenoliths provide re-equilibration temperature estimates from 860-1075°C (for the whole suite) and temperature-pressure estimates for the garnet metawebsterites from 1055-1070°C and 1.2-1.4 GPa. This gives a Miocene mantle geotherm gradient at least 80-l 30°C higher than the Southeast Australian (SEA) western Victorian geotherms. However, considerations of Moho depths from new seismic surveys below Table Cape (�32 km) suggest that the indicated geotherm is more strongly pcrrurbed in its lower levels than at the mantle-crust transition. This localised perturbation is attributed to adjacent magma chamber activity in the mantle (Boat Harbour basalts) just prior to Table Cape vent activity. Tasmanian Miocene geotherms (Table Cape, Bow Hill) achieve relatively high gradients and reinforce sugges tions of local variation in East Australian geothermal gradients. They illustrate the potential complexities in comparing xenolith-derived geotherms from diff erent areas in general, both from thermometer/barometer selection and from associated magmatic heat inputs.

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New evidence of Tasmania's tectonic history from a novel seismic experiment

Cited by 25 publications

References 10 publications

Seismic Traveltime Tomography of the Crust and Lithosphere

Seismic Traveltime Tomography of the Crust and Lithosphere

The Tamar Trough revisited: correlations berween sedimentary beds, basalts, their ages and valley evolution, North Tasmania

Table Cape vent xenolith suite, northwest Tasmania: Mineralogy and implications for crust-mantle lithology and Miocene geotherms in Tasmania

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