Field, petrophysical and carbon isotope studies on the Lapland Granulite Belt: implications for deep continental crust
ABSTRACT The Palaeoproterozoic Lapland Granulite Belt is a seismically reflective and electrically conductive sequence of deep crustal (6–9 kbar) rocks in the northern Fennoscandian Shield. It is composed of garnet‐sillimanite gneisses (khondalites) and pyroxene granulites (enderbites) which in cert...
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crwiley:10.1111/j.1365-3121.1996.tb00724.x 2024-06-02T08:06:32+00:00 Field, petrophysical and carbon isotope studies on the Lapland Granulite Belt: implications for deep continental crust Korja, T. Tuisku, P. Pernu, T. Karhu, J. 1996 http://dx.doi.org/10.1111/j.1365-3121.1996.tb00724.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-3121.1996.tb00724.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3121.1996.tb00724.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Terra Nova volume 8, issue 1, page 48-58 ISSN 0954-4879 1365-3121 journal-article 1996 crwiley https://doi.org/10.1111/j.1365-3121.1996.tb00724.x 2024-05-03T10:34:59Z ABSTRACT The Palaeoproterozoic Lapland Granulite Belt is a seismically reflective and electrically conductive sequence of deep crustal (6–9 kbar) rocks in the northern Fennoscandian Shield. It is composed of garnet‐sillimanite gneisses (khondalites) and pyroxene granulites (enderbites) which in certain thrust sheets form about 500 m thick interlayers. The structure was formed by the intrusion of intermediate to basic magmas into turbiditic sedimentary rocks under granulite facies metamorphism accompanied by shearing of the deep crust about 1.93–1.90 Gyr ago (Gal. Granulites were upthrust 1.90–1.87 Ga and the belt was divided by crustal scale duplexing into four structural units whose layered structure was preserved. The thrust structures are recognized by the repetition of lithological ensembles and by discordant structural patterns well distinguishable in airborne magnetic and electromagnetic data. Thrusting gave rise to clockwise pressure‐temperature evolution of the belt. However, some basic rocks possibly record an isobaric cooling path. The low bulk resistivity of the belt (200–1000 Ωm) is caused by interconnected graphite and subordinate sulphides in shear zones. On the basis of carbon isotope ratios this graphite is derived mostly from sedimentary organic carbon. The seismic reflectivity of the belt may be caused by velocity and density differences between pyroxene granulites and khondalites, as well as by shear zones. Article in Journal/Newspaper Fennoscandian Lapland Wiley Online Library Terra Nova 8 1 48 58 |
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language |
English |
description |
ABSTRACT The Palaeoproterozoic Lapland Granulite Belt is a seismically reflective and electrically conductive sequence of deep crustal (6–9 kbar) rocks in the northern Fennoscandian Shield. It is composed of garnet‐sillimanite gneisses (khondalites) and pyroxene granulites (enderbites) which in certain thrust sheets form about 500 m thick interlayers. The structure was formed by the intrusion of intermediate to basic magmas into turbiditic sedimentary rocks under granulite facies metamorphism accompanied by shearing of the deep crust about 1.93–1.90 Gyr ago (Gal. Granulites were upthrust 1.90–1.87 Ga and the belt was divided by crustal scale duplexing into four structural units whose layered structure was preserved. The thrust structures are recognized by the repetition of lithological ensembles and by discordant structural patterns well distinguishable in airborne magnetic and electromagnetic data. Thrusting gave rise to clockwise pressure‐temperature evolution of the belt. However, some basic rocks possibly record an isobaric cooling path. The low bulk resistivity of the belt (200–1000 Ωm) is caused by interconnected graphite and subordinate sulphides in shear zones. On the basis of carbon isotope ratios this graphite is derived mostly from sedimentary organic carbon. The seismic reflectivity of the belt may be caused by velocity and density differences between pyroxene granulites and khondalites, as well as by shear zones. |
format |
Article in Journal/Newspaper |
author |
Korja, T. Tuisku, P. Pernu, T. Karhu, J. |
spellingShingle |
Korja, T. Tuisku, P. Pernu, T. Karhu, J. Field, petrophysical and carbon isotope studies on the Lapland Granulite Belt: implications for deep continental crust |
author_facet |
Korja, T. Tuisku, P. Pernu, T. Karhu, J. |
author_sort |
Korja, T. |
title |
Field, petrophysical and carbon isotope studies on the Lapland Granulite Belt: implications for deep continental crust |
title_short |
Field, petrophysical and carbon isotope studies on the Lapland Granulite Belt: implications for deep continental crust |
title_full |
Field, petrophysical and carbon isotope studies on the Lapland Granulite Belt: implications for deep continental crust |
title_fullStr |
Field, petrophysical and carbon isotope studies on the Lapland Granulite Belt: implications for deep continental crust |
title_full_unstemmed |
Field, petrophysical and carbon isotope studies on the Lapland Granulite Belt: implications for deep continental crust |
title_sort |
field, petrophysical and carbon isotope studies on the lapland granulite belt: implications for deep continental crust |
publisher |
Wiley |
publishDate |
1996 |
url |
http://dx.doi.org/10.1111/j.1365-3121.1996.tb00724.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-3121.1996.tb00724.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3121.1996.tb00724.x |
genre |
Fennoscandian Lapland |
genre_facet |
Fennoscandian Lapland |
op_source |
Terra Nova volume 8, issue 1, page 48-58 ISSN 0954-4879 1365-3121 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/j.1365-3121.1996.tb00724.x |
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Terra Nova |
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8 |
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1 |
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48 |
op_container_end_page |
58 |
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1800751489657864192 |