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RST Apology to Tasmanian Aboriginal people 2021.

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

Papers & Reports

Summary

The Miocene Table Cape vent erupted a diverse mantle-crust xenolith suite within its fractionated nephelinitic matrix. Assemblages include mantle metaperidotites, garnet-metawebsterites and rarer garnet-metadinopyroxenitcs, garnct-mctawehrlites, metawebsterites and crusta] two-pyroxene granulites. Most metapyroxenires 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 860-1 0750C (for the whole suite) and temperature-pressure estimates for the garnet metawebsterires from 1055-1 070°C and 1.2-1.4 CPa. This gives a Miocene mantle geotherm gradient at least 80–130°C higher than the Southeast Australian (SEA) western Victorian geotherms. However, considerations of Moho from new seismic surveys below Table Cape (~.32 km) suggest that the indicated georherm is more strongly perturbed in its lower levels than at the mantle-crust transition. This localised perturbation is attributed to magma chamber in the mantle (Boat Harbour just prior to Table Cape vent activity. Tasmanian Miocene geotherms (Table Cape, Bow Hill) achieve relatively high gradients and reinforce suggestions of local variation in East Australian geothermal gradients, They illustrate the potential complexities in com paring xenolith- derived geotherms from different areas in general, both from thermometer/barometer selection and from associated magmatic heat inputs.

 

Keywords:

Royal Society of Tasmania, RST, Van Diemens Land, natural history, science, ecology, taxonomy, botany, zoology, geology, geography, papers & proceedings, Australia, UTAS Library

Acknowledgement of Country

The Royal Society of Tasmania acknowledges, with deep respect, the traditional owners of this land, and the ongoing custodianship of the Aboriginal people of Tasmania. The Society pays respect to Elders past, present and emerging. We acknowledge that Tasmanian Aboriginal Peoples have survived severe and unjust impacts resulting from invasion and dispossession of their Country. As an institution dedicated to the advancement of knowledge, the Royal Society of Tasmania recognises Aboriginal cultural knowledge and practices and seeks to respect and honour these traditions and the deep understanding they represent.

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On 15 February 2021, the Royal Society of Tasmania offered a formal Apology to the Tasmanian Aboriginal people.