Ordovician stratigraphy in the western Helgeland Nappe Complex in the Brønnøysund area, North-central Norway.
In the western part of the Helgeland Nappe Complex, a small ophiolite fragment (the Bolvær Complex) and a metasedimentary succession (the Brønnøysund Group) are exposed on several islands to the west of Brønnøysund. The Bolvær Complex was emplaced, uplifted and subject to subaerial weathering and er...
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ftnorgesgu:oai:openarchive.ngu.no:11250/2674124 2023-05-15T15:47:03+02:00 Ordovician stratigraphy in the western Helgeland Nappe Complex in the Brønnøysund area, North-central Norway. Heldal, Tom 2001 application/pdf https://hdl.handle.net/11250/2674124 eng eng NGU Bulletin (438) https://hdl.handle.net/11250/2674124 Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no CC-BY 47-61 KONGLOMERAT KALKSTEIN OFIOLITT ORDOVICIUM SANDSTEIN SEDIMENTÆR BERGART STRATIGRAFI Journal article 2001 ftnorgesgu 2022-07-03T15:26:46Z In the western part of the Helgeland Nappe Complex, a small ophiolite fragment (the Bolvær Complex) and a metasedimentary succession (the Brønnøysund Group) are exposed on several islands to the west of Brønnøysund. The Bolvær Complex was emplaced, uplifted and subject to subaerial weathering and erosion prior to the deposition of the Brønnøysund Group. The uncomformity defines an irregular topographic surface which was gradually filled with sediments during a regional transgression, probably influenced by active tectonics. The sedimentation of the Brønnøysund Group initially started with the build-up of a coastal setting, delivering coarse and fince clastiscs into a shallow-marine environment (Risøy Formation). This formation is stratigraphically overlain by calcareous turbidites (Torgnes Formation), pelites (Aspøy Formation) and carbonate rocks (Toftsund Formation). The Brønnøysund Group is correlated with several cover sequences above ophiolites in the Helgeland Nappe Complex, and deposition in Early to Middle Orodovician time is suggested. The clast population in conglomerates and the composition of finer clastic sediments show an exotic, ensialic source for the detritus, in addition to the ophiolite. The ensialic source consisted essentially ofpsammites and schists, deformed and metamorphosed prior to the deposition of the Brønnøysund Group. 49802 Article in Journal/Newspaper Brønnøysund Helgeland NGU Open Archive (Geological Survey of Norway) Aspøy ENVELOPE(7.946,7.946,63.041,63.041) Bolvær ENVELOPE(12.067,12.067,65.483,65.483) Brønnøysund ENVELOPE(12.213,12.213,65.475,65.475) Helgeland Norway Torgnes ENVELOPE(12.105,12.105,65.496,65.496) |
institution |
Open Polar |
collection |
NGU Open Archive (Geological Survey of Norway) |
op_collection_id |
ftnorgesgu |
language |
English |
topic |
KONGLOMERAT KALKSTEIN OFIOLITT ORDOVICIUM SANDSTEIN SEDIMENTÆR BERGART STRATIGRAFI |
spellingShingle |
KONGLOMERAT KALKSTEIN OFIOLITT ORDOVICIUM SANDSTEIN SEDIMENTÆR BERGART STRATIGRAFI Heldal, Tom Ordovician stratigraphy in the western Helgeland Nappe Complex in the Brønnøysund area, North-central Norway. |
topic_facet |
KONGLOMERAT KALKSTEIN OFIOLITT ORDOVICIUM SANDSTEIN SEDIMENTÆR BERGART STRATIGRAFI |
description |
In the western part of the Helgeland Nappe Complex, a small ophiolite fragment (the Bolvær Complex) and a metasedimentary succession (the Brønnøysund Group) are exposed on several islands to the west of Brønnøysund. The Bolvær Complex was emplaced, uplifted and subject to subaerial weathering and erosion prior to the deposition of the Brønnøysund Group. The uncomformity defines an irregular topographic surface which was gradually filled with sediments during a regional transgression, probably influenced by active tectonics. The sedimentation of the Brønnøysund Group initially started with the build-up of a coastal setting, delivering coarse and fince clastiscs into a shallow-marine environment (Risøy Formation). This formation is stratigraphically overlain by calcareous turbidites (Torgnes Formation), pelites (Aspøy Formation) and carbonate rocks (Toftsund Formation). The Brønnøysund Group is correlated with several cover sequences above ophiolites in the Helgeland Nappe Complex, and deposition in Early to Middle Orodovician time is suggested. The clast population in conglomerates and the composition of finer clastic sediments show an exotic, ensialic source for the detritus, in addition to the ophiolite. The ensialic source consisted essentially ofpsammites and schists, deformed and metamorphosed prior to the deposition of the Brønnøysund Group. 49802 |
format |
Article in Journal/Newspaper |
author |
Heldal, Tom |
author_facet |
Heldal, Tom |
author_sort |
Heldal, Tom |
title |
Ordovician stratigraphy in the western Helgeland Nappe Complex in the Brønnøysund area, North-central Norway. |
title_short |
Ordovician stratigraphy in the western Helgeland Nappe Complex in the Brønnøysund area, North-central Norway. |
title_full |
Ordovician stratigraphy in the western Helgeland Nappe Complex in the Brønnøysund area, North-central Norway. |
title_fullStr |
Ordovician stratigraphy in the western Helgeland Nappe Complex in the Brønnøysund area, North-central Norway. |
title_full_unstemmed |
Ordovician stratigraphy in the western Helgeland Nappe Complex in the Brønnøysund area, North-central Norway. |
title_sort |
ordovician stratigraphy in the western helgeland nappe complex in the brønnøysund area, north-central norway. |
publishDate |
2001 |
url |
https://hdl.handle.net/11250/2674124 |
long_lat |
ENVELOPE(7.946,7.946,63.041,63.041) ENVELOPE(12.067,12.067,65.483,65.483) ENVELOPE(12.213,12.213,65.475,65.475) ENVELOPE(12.105,12.105,65.496,65.496) |
geographic |
Aspøy Bolvær Brønnøysund Helgeland Norway Torgnes |
geographic_facet |
Aspøy Bolvær Brønnøysund Helgeland Norway Torgnes |
genre |
Brønnøysund Helgeland |
genre_facet |
Brønnøysund Helgeland |
op_source |
47-61 |
op_relation |
NGU Bulletin (438) https://hdl.handle.net/11250/2674124 |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no |
op_rightsnorm |
CC-BY |
_version_ |
1766381866835771392 |