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Abstract

The lower Palaeozoic Mathinna Beds are intruded and contact metamorphosed by sixteen Devonian, granitoid plutons in the southern Ferneaux Group, northeastern Tasmania.
Contact metamorphic aureoles range from 200m to 2km wide and on Clarke Island the
metamorphic assemblage cordierite-andalusite-biotite-quartz-potash feldspar is preserved.
Approximately 70 per cent by area of the granitoid terrain is composed of
garnet and/or cordierite-bearing biotite granites (eight plutons), 20 per cent biotite
granites (five plutons) including two altered plutons, and 10 per cent hornblendebiotite
granodiorites (three plutons). The granitoids were intruded by widespread
dolerite dykes of pre-Tertiary age. Cainozoic sedimentary sequences are thin and
irregularly distributed. Mid-Tertiary sediments formed in lagoonal and shallow water
marine environments have been reworked during the Quaternary by alluvial and aeolian
processes In the Rooks River tinfield the cassiterite, which was eroded from
pervasively altered Rooks River granite, is thought to be a lag deposit derived by
reworking of the Tertiary sediments. Potential areas of exploration include
southern end of the Lee River valley near the strongly altered RooksRiver granite and
the alluvial fans north and south of the altered Hogans Hill granite pluton.

Item Type:	Article
Authors/Creators:	Cocker, JD
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
Collections:	Royal Society Collection > Papers & Proceedings of the Royal Society of Tasmania
Additional Information:	Copyright Royal Society of Tasmania
Item Statistics:	View statistics for this item

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