Amphiboles and biotite in relation to the stages of metamorphism in granogabbro

• Main Author: W. Smulikowski
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1974
• Subjects: Bratteggdalen; Eimfjellet; Hornsund; Spitsbergen
• 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

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-