Transition of granite to quartz-kyanite rock at Halsjoberg, southern Sweden; consequence of acid leaching and later metamorphism

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Authors:Larsson, Daniel
Volume Title:GFF
Source:GFF, 123(4), p.237-246. Publisher: Geological Society of Sweden, Stockholm, Sweden. ISSN: 1103-5897
Publication Date:2001
Note:In English. 43 refs.; illus., incl. sect., 2 tables, geol. sketch maps
Summary:Small deposits of rare Al-phosphates, rutile and abundant kyanite occur at Halsjöberg, Diksberg, Hökensas and Västana in S Sweden. Gradual transitions between magmatic rocks and high-alumina rocks consisting of quartz, kyanite, rutile and Al-phosphates have been noted at Halsjöberg and Hökensas. These transitions reveal that hydrothermal leaching formed the high-alumina assemblage in a process where alkalis and other rock-forming elements have been leached, leaving a residual rock mainly composed of high-alumina minerals and quartz. A partly amphibolitized dolerite cuts the high-alumina rock at Halsjöberg, postdating this hydrothermal event. Textural relations, character of alteration and considerations of the origin of acid fluids suggest that hydrothermal leaching driven by magmatic activity occurred at brittle conditions before metamorphism. Alteration of intrusive rocks and the structurally controlled character of alteration furthermore suggest a magmatic hydrothermal environment. The formation of Al-phosphates seems to be related to the phase of hydrothermal leaching, although subsequent regional metamorphism to a large extent determined the present assemblage. [B.L.]
Subsections:Metamorphism: thermal, metasomatic
Subjects:Chemical composition; Diabase; Framework silicates; Granites; Hydrothermal alteration; Igneous rocks; Inorganic acids; Kyanite; Leaching; Metamorphism; Metasomatism; Mineral composition; Nesosilicates; Orthosilicates; Plutonic rocks; Quartz; Silica minerals; Silicates; Sulfuric acid; Europe; Scandinavia; Sweden; Western Europe; Halsjoberg Sweden; Southern Sweden
Abstract Numbers:02M/2259
Record ID:2004012047
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from Geoline, Bundesanstalt fur Geowissenschaften und Rohstoffe
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