Paleoproterozoic Metamorphism of the Archean Tuntsa Suite, Northern Fennoscandian Shield

Show full item record



Permalink

http://hdl.handle.net/10138/326469

Citation

Holtta , P , Kivisaari , T , Huhma , H , Rollinson , G , Kurhila , M & Butcher , A R 2020 , ' Paleoproterozoic Metamorphism of the Archean Tuntsa Suite, Northern Fennoscandian Shield ' , Minerals , vol. 10 , no. 11 , 1034 . https://doi.org/10.3390/min10111034

Title: Paleoproterozoic Metamorphism of the Archean Tuntsa Suite, Northern Fennoscandian Shield
Author: Holtta, Pentti; Kivisaari, Tiia; Huhma, Hannu; Rollinson, Gavyn; Kurhila, Matti; Butcher, Alan R.
Contributor organization: Department of Geosciences and Geography
Date: 2020-11
Language: eng
Number of pages: 31
Belongs to series: Minerals
ISSN: 2075-163X
DOI: https://doi.org/10.3390/min10111034
URI: http://hdl.handle.net/10138/326469
Abstract: The Tuntsa Suite is a polymetamorphic Archean complex mainly consisting of metasedimentary gneisses. At least two strong metamorphic events can be distinguished in the area. The first took place at high temperatures in the Neoarchean at around 2.70-2.64 Ga, indicated by migmatisation and U-Pb ages of metamorphic zircon. During the Paleoproterozoic, metasedimentary gneisses were penetratively deformed and recrystallized under medium pressures producing staurolite, kyanite and garnet-bearing mineral assemblages. The suggested Paleoproterozoic PT path was clockwise where the temperature and pressure first increased to 540-550 degrees C and 6 kbar, crystallizing high Ca/low Mg garnet cores. The mineral compositions show that commonly garnet core was not in chemical equilibrium with staurolite but crystallized earlier, although garnet-staurolite-kyanite assemblages are common. The temperature and pressure increased to c. 650 degrees C and 8 kbars where staurolite and kyanite coexist. This was followed by decompression down to c. 550-600 degrees C and 3-4 kbars, shown by andalusite crystallization and cordierite formed in the breakdown of staurolite and biotite + kyanite. The observed garnet zoning where Mg increases and Ca decreases from the core to the rim was developed with both increasing and decreasing pressure, depending on the effective bulk composition. The U-Pb and Sm-Nd age determinations for monazite and garnet show that the Paleoproterozoic metamorphic cycle took place at 1.84-1.79 Ga, related with thrusting of the Lapland granulites onto the adjacent terranes and subsequent exhumation.
Subject: Archean
Paleoproterozoic
metamorphism
age determination
Fennoscandian Shield
Finland
BELOMORIAN ECLOGITE PROVINCE
MIGMATITIC GRANULITE COMPLEXES
U-PB AGES
SM-ND
KOLA-PENINSULA
MOBILE BELT
REGIONAL METAMORPHISM
TECTONIC EVOLUTION
KARELIAN PROVINCE
CENTRAL FINLAND
1171 Geosciences
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


Files in this item

Total number of downloads: Loading...

Files Size Format View
minerals_10_01034_v2.pdf 4.911Mb PDF View/Open

This item appears in the following Collection(s)

Show full item record