The regional distribution of zeolites in the basalts of the Faroe Islands and the significance of zeolites as palaeotemperature indicators
The first maps of the regional distribution of zeolites in the Palaeogene basalt plateau of the Faroe Islands are presented. The zeolite zones (thomsonite-chabazite, analcite, mesolite, stilbite-heulandite, laumontite) continue below sea level and reach a depth of 2200 m in the Lopra-1/1A well. Belo...
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Geological Survey of Denmark and Greenland (GEUS)
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ftjgeusbullet:oai:geusjournals.org:article/4865 2023-05-15T15:45:46+02:00 The regional distribution of zeolites in the basalts of the Faroe Islands and the significance of zeolites as palaeotemperature indicators Jørgensen, Ole 2006-05-31 application/pdf https://geusbulletin.org/index.php/geusb/article/view/4865 https://doi.org/10.34194/geusb.v9.4865 eng eng Geological Survey of Denmark and Greenland (GEUS) https://geusbulletin.org/index.php/geusb/article/view/4865/10498 https://geusbulletin.org/index.php/geusb/article/view/4865 doi:10.34194/geusb.v9.4865 GEUS Bulletin; Vol. 9 (2006): Scientific results from the deepened Lopra-1 borehole, Faroe Islands; 123-156 2597-2154 2597-2162 Faroe Islands Palaeogene basalt plateau zeolite zone palaeotemperature indicators info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Peer-reviewed Article. 2006 ftjgeusbullet https://doi.org/10.34194/geusb.v9.4865 2022-03-15T17:22:19Z The first maps of the regional distribution of zeolites in the Palaeogene basalt plateau of the Faroe Islands are presented. The zeolite zones (thomsonite-chabazite, analcite, mesolite, stilbite-heulandite, laumontite) continue below sea level and reach a depth of 2200 m in the Lopra-1/1A well. Below this level, a high temperature zone occurs characterised by prehnite and pumpellyite. The stilbite-heulandite zone is the dominant mineral zone on the northern island, Vágar, the analcite and mesolite zones are the dominant ones on the southern islands of Sandoy and Suðuroy and the thomsonite-chabazite zone is dominant on the two northeastern islands of Viðoy and Borðoy. It is estimated that zeolitisation of the basalts took place at temperatures between about 40°C and 230°C. Palaeogeothermal gradients are estimated to have been 66 ± 9°C/km in the lower basalt formation of the Lopra area of Suðuroy, the southernmost island, 63 ± 8°C/km in the middle basalt formation on the northernmost island of Vágar and 56 ± 7°C/km in the upper basalt formation on the central island of Sandoy. A linear extrapolation of the gradient from the Lopra area places the palaeosurface of the basalt plateau near to the top of the lower basalt formation. On Vágar, the palaeosurface was somewhere between 1700 m and 2020 m above the lower formation while the palaeosurface on Sandoy was between 1550 m and 1924 m above the base of the upper formation. The overall distribution of zeolites reflects primarily variations in the maximum depth of burial of the basalt rather than differences in heat flow. The inferred thinning of the middle and upper basalt formation from the central to the southern part of the Faroes is in general agreement with a northerly source area for these basalts, centred around the rift between the Faroes and Greenland. The regional zeolite distribution pattern is affected by local perturbations of the mineral zone boundaries that reflect local differences in the temperature, perhaps related to the circulation of water in the underground. The zonal distribution pattern suggests that these temperature anomalies are in part related to NW–SE-trending eruption fissures or zones of weakness separating the present islands and are subparallel to transfer zones in the Faroe–Shetland Basin. Both the regional and the local distribution of zeolite assemblages are probably a reflection of the basic volcanic-tectonic pattern of the Faroe Islands. Article in Journal/Newspaper Borðoy Faroe Islands Faroes Greenland Sandoy Suðuroy Suðuroy Vágar Viðoy GEUS Bulletin (Geological Survey of Denmark and Greenland) Faroe Islands Greenland Lopra ENVELOPE(-6.771,-6.771,61.444,61.444) Sandoy ENVELOPE(-6.776,-6.776,61.854,61.854) Suðuroy ENVELOPE(-6.830,-6.830,61.518,61.518) Vágar ENVELOPE(-7.260,-7.260,62.095,62.095) Borðoy ENVELOPE(-6.530,-6.530,62.266,62.266) Viðoy ENVELOPE(-6.511,-6.511,62.327,62.327) Geological Survey of Denmark and Greenland (GEUS) Bulletin 9 123 156 |
institution |
Open Polar |
collection |
GEUS Bulletin (Geological Survey of Denmark and Greenland) |
op_collection_id |
ftjgeusbullet |
language |
English |
topic |
Faroe Islands Palaeogene basalt plateau zeolite zone palaeotemperature indicators |
spellingShingle |
Faroe Islands Palaeogene basalt plateau zeolite zone palaeotemperature indicators Jørgensen, Ole The regional distribution of zeolites in the basalts of the Faroe Islands and the significance of zeolites as palaeotemperature indicators |
topic_facet |
Faroe Islands Palaeogene basalt plateau zeolite zone palaeotemperature indicators |
description |
The first maps of the regional distribution of zeolites in the Palaeogene basalt plateau of the Faroe Islands are presented. The zeolite zones (thomsonite-chabazite, analcite, mesolite, stilbite-heulandite, laumontite) continue below sea level and reach a depth of 2200 m in the Lopra-1/1A well. Below this level, a high temperature zone occurs characterised by prehnite and pumpellyite. The stilbite-heulandite zone is the dominant mineral zone on the northern island, Vágar, the analcite and mesolite zones are the dominant ones on the southern islands of Sandoy and Suðuroy and the thomsonite-chabazite zone is dominant on the two northeastern islands of Viðoy and Borðoy. It is estimated that zeolitisation of the basalts took place at temperatures between about 40°C and 230°C. Palaeogeothermal gradients are estimated to have been 66 ± 9°C/km in the lower basalt formation of the Lopra area of Suðuroy, the southernmost island, 63 ± 8°C/km in the middle basalt formation on the northernmost island of Vágar and 56 ± 7°C/km in the upper basalt formation on the central island of Sandoy. A linear extrapolation of the gradient from the Lopra area places the palaeosurface of the basalt plateau near to the top of the lower basalt formation. On Vágar, the palaeosurface was somewhere between 1700 m and 2020 m above the lower formation while the palaeosurface on Sandoy was between 1550 m and 1924 m above the base of the upper formation. The overall distribution of zeolites reflects primarily variations in the maximum depth of burial of the basalt rather than differences in heat flow. The inferred thinning of the middle and upper basalt formation from the central to the southern part of the Faroes is in general agreement with a northerly source area for these basalts, centred around the rift between the Faroes and Greenland. The regional zeolite distribution pattern is affected by local perturbations of the mineral zone boundaries that reflect local differences in the temperature, perhaps related to the circulation of water in the underground. The zonal distribution pattern suggests that these temperature anomalies are in part related to NW–SE-trending eruption fissures or zones of weakness separating the present islands and are subparallel to transfer zones in the Faroe–Shetland Basin. Both the regional and the local distribution of zeolite assemblages are probably a reflection of the basic volcanic-tectonic pattern of the Faroe Islands. |
format |
Article in Journal/Newspaper |
author |
Jørgensen, Ole |
author_facet |
Jørgensen, Ole |
author_sort |
Jørgensen, Ole |
title |
The regional distribution of zeolites in the basalts of the Faroe Islands and the significance of zeolites as palaeotemperature indicators |
title_short |
The regional distribution of zeolites in the basalts of the Faroe Islands and the significance of zeolites as palaeotemperature indicators |
title_full |
The regional distribution of zeolites in the basalts of the Faroe Islands and the significance of zeolites as palaeotemperature indicators |
title_fullStr |
The regional distribution of zeolites in the basalts of the Faroe Islands and the significance of zeolites as palaeotemperature indicators |
title_full_unstemmed |
The regional distribution of zeolites in the basalts of the Faroe Islands and the significance of zeolites as palaeotemperature indicators |
title_sort |
regional distribution of zeolites in the basalts of the faroe islands and the significance of zeolites as palaeotemperature indicators |
publisher |
Geological Survey of Denmark and Greenland (GEUS) |
publishDate |
2006 |
url |
https://geusbulletin.org/index.php/geusb/article/view/4865 https://doi.org/10.34194/geusb.v9.4865 |
long_lat |
ENVELOPE(-6.771,-6.771,61.444,61.444) ENVELOPE(-6.776,-6.776,61.854,61.854) ENVELOPE(-6.830,-6.830,61.518,61.518) ENVELOPE(-7.260,-7.260,62.095,62.095) ENVELOPE(-6.530,-6.530,62.266,62.266) ENVELOPE(-6.511,-6.511,62.327,62.327) |
geographic |
Faroe Islands Greenland Lopra Sandoy Suðuroy Vágar Borðoy Viðoy |
geographic_facet |
Faroe Islands Greenland Lopra Sandoy Suðuroy Vágar Borðoy Viðoy |
genre |
Borðoy Faroe Islands Faroes Greenland Sandoy Suðuroy Suðuroy Vágar Viðoy |
genre_facet |
Borðoy Faroe Islands Faroes Greenland Sandoy Suðuroy Suðuroy Vágar Viðoy |
op_source |
GEUS Bulletin; Vol. 9 (2006): Scientific results from the deepened Lopra-1 borehole, Faroe Islands; 123-156 2597-2154 2597-2162 |
op_relation |
https://geusbulletin.org/index.php/geusb/article/view/4865/10498 https://geusbulletin.org/index.php/geusb/article/view/4865 doi:10.34194/geusb.v9.4865 |
op_doi |
https://doi.org/10.34194/geusb.v9.4865 |
container_title |
Geological Survey of Denmark and Greenland (GEUS) Bulletin |
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123 |
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1766380320413712384 |