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ABSTRACT. Amphibole in the lower parts of the Lilloise layered intrusion occurs interstitially and as a replace-ment of pyroxene; inthe upper ocks it is a major cumulus phase. There is an overall trend of increasing Fe/(Fe+ Mg) with height, Coupled substitutions which effect the variation in composi...
| Main Authors: | , , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.630.7831 http://www.minersoc.org/pages/Archive-MM/Volume_45/45-337-47.pdf |
| Summary: | ABSTRACT. Amphibole in the lower parts of the Lilloise layered intrusion occurs interstitially and as a replace-ment of pyroxene; inthe upper ocks it is a major cumulus phase. There is an overall trend of increasing Fe/(Fe+ Mg) with height, Coupled substitutions which effect the variation in composition of the amphiboles are chiefly Na,K(A)+AI(T) for [7A+Si(T) and Ti+AI(T) for Fea+(C)+ Si(T). There is considerable variation in com-position both on the specimen scale and within individual grains. This variation, plus scatter found in plots of the coupled substitutions, is partly attributed to many of the amphiboles having replaced pyroxene and also to the effects of magmatic-hydrothermal fluids. THE Lilloise layered intrusion is one of the major Tertiary plutonic centres in East Greenland. It is a high-level, epizonal intrusion which cuts the regional flood basalts about 120 km east of the Skaergaard intrusion and 20 km inland from the Blosseville coast (fig. 1). The 5 x 9 km outcrop is in difficult country and the eventual success of attempts to gain access to the intrusion owed much to the encouragement of Professor W. A. Deer. Reconnaissance observations were made by Brown |
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