The prehistory of Suomussalmi, eastern Finland : the first billion years as revealed by isotopes and the composition of granitoid suites
The four papers summarized in this thesis deal with the Archean and earliest Paleoproterozoic granitoid suites observed in the Suomussalmi district, eastern Finland. Geologically, the area belongs to the Kianta Complex of the Western Karelian Terrane in the Karelian Province of the Fennoscandian shi...
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Helsingin yliopisto
2011
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ftunivhelsihelda:oai:helda.helsinki.fi:10138/27056 2023-08-20T04:06:28+02:00 The prehistory of Suomussalmi, eastern Finland : the first billion years as revealed by isotopes and the composition of granitoid suites Suomussalmen esihistoria, ensimmäinen miljardivuotta granitoidien koostumusten ja isotooppien valossa Mikkola, Perttu Martin, Hervé University of Helsinki, Faculty of Science, Department of Geosciences and Geography, Division of Geology Geological Survey of Finland Helsingin yliopisto, matemaattis-luonnontieteellinen tiedekunta, geotieteiden ja maantieteen laitos Helsingfors universitet, matematisk-naturvetenskapliga fakulteten, institutionen för geovetenskaper och geografi Hölttä, Pentti Rämö, Tapani 2011-06-23T11:33:17Z application/pdf http://hdl.handle.net/10138/27056 eng eng Helsingin yliopisto Helsingfors universitet University of Helsinki URN:ISBN:978-952-217-164-1 Tammerprint Oy: Geologian tutkimuskeskus, 2011 http://hdl.handle.net/10138/27056 URN:ISBN:978-952-217-165-8 Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty. This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited. Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden. geologia Text Doctoral dissertation (article-based) Artikkeliväitöskirja Artikelavhandling doctoralThesis 2011 ftunivhelsihelda 2023-07-28T06:06:18Z The four papers summarized in this thesis deal with the Archean and earliest Paleoproterozoic granitoid suites observed in the Suomussalmi district, eastern Finland. Geologically, the area belongs to the Kianta Complex of the Western Karelian Terrane in the Karelian Province of the Fennoscandian shield. The inherited zircons up to 3440 Ma old together with Sm Nd and Pb Pb data confirm the existence of previously anticipated Paleoarchean protocrust in Suomussalmi. The general timeline of granitoid magmatism is similar to that of the surrounding areas. TTG magmatism occurred in three distinct phases: ca 2.95 Ga, 2.83 2.78 Ga and 2.76 2.74 Ga. In Suomussalmi the TTGs sensu stricto (K2O/Na2O less than 0.5) belong to the low-HREE type and are interpreted as partial melts of garnet amphibolites, which did not significantly interact with mantle peridotites. Transitional TTGs (K2O/Na2O more than 0.5), present in Suomussalmi and absent from surrounding areas, display higher LILE concentrations, but otherwise closely resemble the TTGs sensu stricto and indicate that recycling of felsic crust commenced in Suomussalmi 200 Ma earlier than in surrounding areas. The youngest TTG phase was coeval with the intrusion of the Likamännikkö quartz alkali feldspar syenite (2741 ± 2 Ma) complex. The complex contains angular fragments of ultrabasic rock, which display considerable compositional heterogeneity and are interpreted as cumulates containing clinopyroxene (generally altered to actinolite), apatite, allanite, epidote, and albite. The quartz alkali feldspar syenite cannot be regarded as alkaline sensu stricto, despite clear alkaline affinities. Within Likamännikkö there are also calcite carbonatite patches, which display mantle-like O- and C-isotope values, as well as trace element characteristics consistent with a magmatic origin, and could thus be among the oldest known carbonatites in the world. Sanukitoid (2.73 2.71 Ga) and quartz diorite suites (2.70 Ga) overlap within error margins and display compositional similarities, ... Doctoral or Postdoctoral Thesis Fennoscandian karelia* karelian Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto |
institution |
Open Polar |
collection |
Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto |
op_collection_id |
ftunivhelsihelda |
language |
English |
topic |
geologia |
spellingShingle |
geologia Mikkola, Perttu The prehistory of Suomussalmi, eastern Finland : the first billion years as revealed by isotopes and the composition of granitoid suites |
topic_facet |
geologia |
description |
The four papers summarized in this thesis deal with the Archean and earliest Paleoproterozoic granitoid suites observed in the Suomussalmi district, eastern Finland. Geologically, the area belongs to the Kianta Complex of the Western Karelian Terrane in the Karelian Province of the Fennoscandian shield. The inherited zircons up to 3440 Ma old together with Sm Nd and Pb Pb data confirm the existence of previously anticipated Paleoarchean protocrust in Suomussalmi. The general timeline of granitoid magmatism is similar to that of the surrounding areas. TTG magmatism occurred in three distinct phases: ca 2.95 Ga, 2.83 2.78 Ga and 2.76 2.74 Ga. In Suomussalmi the TTGs sensu stricto (K2O/Na2O less than 0.5) belong to the low-HREE type and are interpreted as partial melts of garnet amphibolites, which did not significantly interact with mantle peridotites. Transitional TTGs (K2O/Na2O more than 0.5), present in Suomussalmi and absent from surrounding areas, display higher LILE concentrations, but otherwise closely resemble the TTGs sensu stricto and indicate that recycling of felsic crust commenced in Suomussalmi 200 Ma earlier than in surrounding areas. The youngest TTG phase was coeval with the intrusion of the Likamännikkö quartz alkali feldspar syenite (2741 ± 2 Ma) complex. The complex contains angular fragments of ultrabasic rock, which display considerable compositional heterogeneity and are interpreted as cumulates containing clinopyroxene (generally altered to actinolite), apatite, allanite, epidote, and albite. The quartz alkali feldspar syenite cannot be regarded as alkaline sensu stricto, despite clear alkaline affinities. Within Likamännikkö there are also calcite carbonatite patches, which display mantle-like O- and C-isotope values, as well as trace element characteristics consistent with a magmatic origin, and could thus be among the oldest known carbonatites in the world. Sanukitoid (2.73 2.71 Ga) and quartz diorite suites (2.70 Ga) overlap within error margins and display compositional similarities, ... |
author2 |
Martin, Hervé University of Helsinki, Faculty of Science, Department of Geosciences and Geography, Division of Geology Geological Survey of Finland Helsingin yliopisto, matemaattis-luonnontieteellinen tiedekunta, geotieteiden ja maantieteen laitos Helsingfors universitet, matematisk-naturvetenskapliga fakulteten, institutionen för geovetenskaper och geografi Hölttä, Pentti Rämö, Tapani |
format |
Doctoral or Postdoctoral Thesis |
author |
Mikkola, Perttu |
author_facet |
Mikkola, Perttu |
author_sort |
Mikkola, Perttu |
title |
The prehistory of Suomussalmi, eastern Finland : the first billion years as revealed by isotopes and the composition of granitoid suites |
title_short |
The prehistory of Suomussalmi, eastern Finland : the first billion years as revealed by isotopes and the composition of granitoid suites |
title_full |
The prehistory of Suomussalmi, eastern Finland : the first billion years as revealed by isotopes and the composition of granitoid suites |
title_fullStr |
The prehistory of Suomussalmi, eastern Finland : the first billion years as revealed by isotopes and the composition of granitoid suites |
title_full_unstemmed |
The prehistory of Suomussalmi, eastern Finland : the first billion years as revealed by isotopes and the composition of granitoid suites |
title_sort |
prehistory of suomussalmi, eastern finland : the first billion years as revealed by isotopes and the composition of granitoid suites |
publisher |
Helsingin yliopisto |
publishDate |
2011 |
url |
http://hdl.handle.net/10138/27056 |
genre |
Fennoscandian karelia* karelian |
genre_facet |
Fennoscandian karelia* karelian |
op_relation |
URN:ISBN:978-952-217-164-1 Tammerprint Oy: Geologian tutkimuskeskus, 2011 http://hdl.handle.net/10138/27056 URN:ISBN:978-952-217-165-8 |
op_rights |
Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty. This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited. Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden. |
_version_ |
1774717517142425600 |