Metamorphosed altered komatiites at Mount Martin, Western Australia — Archaean weathering products metamorphosed at the aluminosilicate triple point
Titel:
Metamorphosed altered komatiites at Mount Martin, Western Australia — Archaean weathering products metamorphosed at the aluminosilicate triple point
Auteur:
Purvis, A.C.
Verschenen in:
Australian journal of earth sciences
Paginering:
Jaargang 31 (1984) nr. 1 pagina's 91-106
Jaar:
1984-03
Inhoud:
Chromium-rich aluminous and ferruginous metamorphic rocks at Mount Martin, Western Australia, can be shown on textural and compositional evidence to have been formed from komatiitic flows and pyroclastics. They were apparently altered initially to quartz-kaolinite ± siderite assemblages, most probably by weathering processes. Metamorphism has produced a variety of mineral assemblages composed variously of quartz, kyanite, andalusite, sillimanite, chloritoid, chlorite, paragonite, muscovite, siderite, biotite, gedrite, almandine, cummingtonite, hornblende and plagioclase, with rutile, ilmenite, pyrite, millerite, polydymite, gersdorffite, pyrrhotite, pentlandite and chromite as accessory minerals. Geothermometry and geobarometry on these samples give substantial support to placing the aluminosilicate triple point at about 500°C and 4kb (400 MPa) pressure.
Tijdschrift beschrijving