Thermal Metamorphism in the trial harbour district, Tasmania
Titel:
Thermal Metamorphism in the trial harbour district, Tasmania
Auteur:
Green, T. H.
Verschenen in:
Australian journal of earth sciences
Paginering:
Jaargang 13 (1966) nr. 2 pagina's 405-418
Jaar:
1966
Inhoud:
A Devonian granite complex intrudes Precambrian and Silurian siltstones and sandstones as well as (?) Cambrian volcanics and dunite. Metamorphism of the Precambrian sediments is slight, and an andalusite-bearing, pelitic hornfels is the only characteristic assemblage. The (?) Cambrian volcanics give rise to a variety of assemblages; (1) lime- and ferromagnesia-rich (hypersthene — cummingtonite — labradorite; diopside — hornblende — labradorite); (2) magnesia-rich (cordierite — hypersthene; cordierite — anthophyllite); (3) ultrabasic (olivine and/or pleonaste). Biotite (or phlogopite) is an almost invariable component, and garnet may also be present in these groups. No significant metamorphism of the dunite is evident; minor development of veins and segregrations of aragonite, magnetite, phlogopite, brucite, chalcedony and antigorite may result from low-grade hydrothermal activity Metamorphic assemblages in calcareous Silurian siltstones contain garnet, diopside, calcite and epidote. A characteristic feature of the contact metamorphic aureole is the occurrence of diopside-rich bodies in granite, volcanic hornfels, quartzite and dunite host rocks.
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