Orbicular quartz diorite in Kemi, NW Finland

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Authors:Perttunen, V.
Author Affiliations:Primary:
Geol. Surv. Finland, Rovaniemi 96101, Finland
Volume Title:Bulletin of the Geological Society of Finland
Source:Bulletin of the Geological Society of Finland, 55(1), p.51-56. Publisher: Geological Society of Finland, Helsinki, Finland. ISSN: 0367-5211
Publication Date:1983
Note:In English. 10 refs.; illus. incl. 9 tables
Summary:This orbicular rock is exposed in one outcrop 10 m2 in size. The country rock is quartz diorite of the Archaean pre-Svecokarelian basement complex. The orbicules are spheroidal or ellipsoidal, 5-16 cm in diameter, and randomly distributed in a leucocratic quartz diorite matrix. They may have from one to five shells, although the single-shelled varieties are the most common. The contacts of the orbicules with the matrix are sharp, but between the shells and against the core they are gradational. The shells are dioritic; their mafic minerals - biotite and hornblende - are radially and tangentially oriented. The majority of the cores are dioritic, but some are ultramafic and rich in biotite. Amphibolite xenoliths have also been found. The Kemi orbicular rock is the first to be found in Archaean bedrock in Finland. [J.M.H.]
Subjects:Archean; Diorites; Igneous rocks; Orbicular texture; Petrology; Plutonic rocks; Precambrian; Quartz diorites; Textures; Europe; Finland; Scandinavia; Western Europe; Kemi; Northwestern Finland
Coordinates:N654500 N654800 E0244000 E0243500
Abstract Numbers:85M/1965
Record ID:1986017218
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique
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