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Abstract

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.

Item Type:	Article
Authors/Creators:	Sutherland, FL
Keywords:	Royal Society of Tasmania, RST, Van Diemens Land, natural history, science, ecology, taxonomy, botany, zoology, geology, geography, papers & proceedings, Australia, UTAS Library
Journal or Publication Title:	Papers and Proceedings of the Royal Society of Tasmania
ISSN:	0080-4703
DOI / ID Number:	https://doi.org/10.26749/rstpp.106.1.43
Collections:	Royal Society Collection > Papers & Proceedings of the Royal Society of Tasmania
Additional Information:	Edited by M.R. Banks. - Copyright Royal Society of Tasmania
Item Statistics:	View statistics for this item

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