Amphiboles and biotite in relation to the stages of metamorphism in granogabbro
spitsbergen, shows a series of amphibole development reflecting its thermal history. A brown Ti-rich hornblende occurs as a late magmatic mantling of pyroxene. Low-grade metamorphism (greenschist facies) was accompanied by the development of actinolite from pyroxene; subsequent amphibolite facies me...
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| Format: | Text |
| Language: | English |
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1974
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.626.9304 http://www.minersoc.org/pages/Archive-MM/Volume_39/39-308-857.pdf |
| Summary: | spitsbergen, shows a series of amphibole development reflecting its thermal history. A brown Ti-rich hornblende occurs as a late magmatic mantling of pyroxene. Low-grade metamorphism (greenschist facies) was accompanied by the development of actinolite from pyroxene; subsequent amphibolite facies metamorphism saw the development of an alkali-rich, blue-green hornblende. The chemical changes in the amphiboles are a succinct illustration of those found in progressive r gional meta-morphism. THE Pre-Cambrian volcanic and subvolcanic Eimfjellet formation, part of the Hecla Hock succession i the Hornsund area of Vestspitsbergen, was metamorphosed during the Caledonian Orogeny. The metamorphosed granogabbro f Bratteggdalen, an interesting mineralogical and textural relict within the amphibolites, was previously described by Smulikowski (I965). An ophitic texture in the rock, with oligoclase-andesine plagioclase, amphiboles, and biotite idiomorphic against he typically xenomorphic quartz and chequer-albite appears to be inherited from the original primary igneous texture. Microscopic study of relicts, reaction-rims, and other mineral interrelations has enabled the reconstruc- |
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