Igneous rocks, Central Plateau

Igneous rocks of basic character dominate the Central Plateau. A great dolerite sheet of Jurassic caps the Plateau and forms its resistant surface. Later, sporadic basalt lavas of Tertiary age fill old drainage depressions cut in the Plateau. The dolerite is far more voluminous, but less varied in i...

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Bibliographic Details
Published in:Papers and Proceedings of The Royal Society of Tasmania
Main Author: Sutherland, FL
Format: Article in Journal/Newspaper
Language:English
Published: 1972
Subjects:
Royal Society of Tasmania
RST
Van Diemens Land
natural history
science
ecology
taxonomy
botany
zoology
geology
geography
papers & proceedings
Australia
UTAS Library
Southern Ocean
Online Access:https://eprints.utas.edu.au/14599/
https://eprints.utas.edu.au/14599/4/Igneous_rocks_Sutherland.pdf
Description
Summary:Igneous rocks of basic character dominate the Central Plateau. A great dolerite sheet of Jurassic caps the Plateau and forms its resistant surface. Later, sporadic basalt lavas of Tertiary age fill old drainage depressions cut in the Plateau. The dolerite is far more voluminous, but less varied in its chemical composition (approx. 1500 cu. km; silica range 52-60%) than the basalts (approx. 15 cu. km; silica range 36-53%). Both these rocks express important events which affected the Southern Hemisphere. The dolerite is the vast molten response to initial fracturing of the southern supercontinent, Gondwanaland, of which Tasmania is a small fragment. The basalts form part of the eastern Australian volcanic province which erupted in response to warping, stretching and increased heat flow along the continental margin as sea-floor spreading opened up the Tasman Sea and Southern Ocean, beginning about 85 million years ago.

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