Geokemisk och kinematisk studie av skjuvzoner i "guldlinjen", Lycksele-Storuman provinsen, norra Sverige
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
A kinematic and geochemical study was carried out in shear zones within the “gold line”in the Lycksele-Storuman province, northern Sweden, with the aid of, field mapping, thinsections and whole rock geochemical data. The shear zones were hosted by metabasalt,metasediments, felsic metavolcanics and metagranodiorite. The area has undergone majordeformation during the Svecofennian orogeny and the shear zones in this study areinterpreted as being formed during this event. The geochemical study was carried out inthree localities, the Grundfors road-cut, Sjöliden and the Svartliden gold mine. The datafrom Grundfors and Sjöliden indicates two different magmatic arc sources, volcanic-arcaffinity for Sjöliden and MORB or Island-arc affinity for Grundfors. The bedrock atGrundfors displayed silicified zones but the protolith for these was not possible todetermine. Sjöliden showed no major elemental exchange between the samples.Svartliden showed two different sources for the metasediments present, acid-arc sourceand an oceanic island-arc source. The metasediments formed from an acid-arc sourcedisplayed a clear relationship based on immobile elements to the highly silicified rocks atSvartliden. This study used one of the acid-arc source metasediments as a precursor witha resulting mass gain of 1800%. The validity of the protolith can be argued. The tectonicstudy was carried out in 5 localities, Grundfors, Sjöliden, Svartliden gold mine, “themylonite” and “the granodiorite”. Indications of two kinematic events were found inGrundfors, Sjöliden and “the mylonite”, one steep reverse movement and a later one withboth extensional and strike-slip components of deformation. The latter showed a dextralshear sense in “the mylonite” while sinistral in the Grundfors outcrops. Sjöliden indicateboth a sinistral and a dextral horizontal component. The kinematic data from Svartlidenshowed only a reverse movement. Svartliden with its ENE striking shear zone and “themylonite” with its NW trending shear zone are interpreted to have formed during N-Scompression. The movements in Grundfors, Sjöliden and “the granodiorite” areinterpreted to have formed during an E-W compression, with either a transpressiveregime or a later orogenic collapse alternatively. The shear zones in this study displayedboth ductile and brittle movements indicating a temperature gradient through the zone.
Place, publisher, year, edition, pages
2011. , 90 p.
Life Earth Science
Bio- och geovetenskaper, Guldlinjen, Svartliden, Kinematik, Silicificering, Skjuvzoner, Massbalans, Lycksele-Storuman, Sjöliden, Grundfors
IdentifiersURN: urn:nbn:se:ltu:diva-53505Local ID: a8461c16-5d95-4113-b227-6681259bdeebOAI: oai:DiVA.org:ltu-53505DiVA: diva2:1026879
Subject / course
Student thesis, at least 30 credits
Geosciences, master's level
Martinsson, OlofSkyttä, Pietari
Validerat; 20111009 (anonymous)2016-10-042016-10-04Bibliographically approved