Geochemistry and petrology of the ferropicrite dikes and associated rocks of Vestfjella, western Dronning Maud Land, Antarctica
This study provides insights into the composition and origin of ferropicrite dikes (FeOtot = 13 17 wt. %; MgO = 13 19 wt. %) and associated meimechite, picrite, picrobasalt, and basalt dikes found at Vestfjella, western Dronning Maud Land, Antarctica. The dikes crosscut Jurassic Karoo continental fl...
Main Author: | |
---|---|
Other Authors: | , , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
Helsingin yliopisto
2011
|
Subjects: | |
Online Access: | http://hdl.handle.net/10138/26267 |
id |
ftunivhelsihelda:oai:helda.helsinki.fi:10138/26267 |
---|---|
record_format |
openpolar |
spelling |
ftunivhelsihelda:oai:helda.helsinki.fi:10138/26267 2023-08-20T04:00:53+02:00 Geochemistry and petrology of the ferropicrite dikes and associated rocks of Vestfjella, western Dronning Maud Land, Antarctica Heinonen, Jussi Gibson, Sally University of Helsinki, Faculty of Science, Department of Geosciences and Geography, Division of Geology Helsingin yliopisto, matemaattis-luonnontieteellinen tiedekunta, geotieteiden ja maantieteen laitos Helsingfors universitet, matematisk-naturvetenskapliga fakulteten, institutionen för geovetenskaper och geografi Rämö, Tapani Luttinen, Arto 2011-05-02T07:52:15Z application/pdf http://hdl.handle.net/10138/26267 eng eng Helsingin yliopisto Helsingfors universitet University of Helsinki URN:ISBN:978-952-10-6309-1 Helsinki: 2011, Department of Geosciences and Geography A. 1798-7911 http://hdl.handle.net/10138/26267 URN:ISBN:978-952-10-6310-7 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 2023-07-28T06:30:49Z This study provides insights into the composition and origin of ferropicrite dikes (FeOtot = 13 17 wt. %; MgO = 13 19 wt. %) and associated meimechite, picrite, picrobasalt, and basalt dikes found at Vestfjella, western Dronning Maud Land, Antarctica. The dikes crosscut Jurassic Karoo continental flood basalts (CFB) that were emplaced during the early stages of the breakup of the Gondwana supercontinent ~180 Ma ago. Selected samples (31 overall from at least eleven dikes) were analyzed for their mineral chemical, major element, trace element, and Sr, Nd, Pb, and Os isotopic compositions. The studied samples can be divided into two geochemically distinct types: (1) The depleted type (24 samples from at least nine dikes) is relatively depleted in the most incompatible elements and exhibits isotopic characteristics (e.g., initial εNd of +4.8 to +8.3 and initial 187Os/188Os of 0.1256 0.1277 at 180 Ma) similar to those of mid-ocean ridge basalts (MORB); (2) The enriched type (7 samples from at least two dikes) exhibits relatively enriched incompatible element and isotopic characteristics (e.g., initial εNd of +1.8 to +3.6 and initial 187Os/188Os of 0.1401 0.1425 at 180 Ma) similar to those of oceanic island basalts. Both magma types have escaped significant contamination by the continental crust. The depleted type is related to the main phase of Karoo magmatism and originated as highly magnesian (MgO up to 25 wt. %) partial melts at high temperatures (mantle potential temperature >1600 °C) and pressures (~5 6 GPa) from a sublithospheric, water-bearing, depleted peridotite mantle source. The enriched type sampled pyroxene-bearing heterogeneities that can be traced down to either recycled oceanic crust or melt-metasomatized portions of the sublithospheric or lithospheric mantle. The source of the depleted type represents a sublithospheric end-member source for many Karoo lavas and has subsequently been sampled by the MORBs of the Indian Ocean. These observations, together with the purported high temperatures, ... Doctoral or Postdoctoral Thesis Antarc* Antarctica Dronning Maud Land Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto Dronning Maud Land Indian Vestfjella ENVELOPE(-14.000,-14.000,-73.167,-73.167) |
institution |
Open Polar |
collection |
Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto |
op_collection_id |
ftunivhelsihelda |
language |
English |
topic |
geologia |
spellingShingle |
geologia Heinonen, Jussi Geochemistry and petrology of the ferropicrite dikes and associated rocks of Vestfjella, western Dronning Maud Land, Antarctica |
topic_facet |
geologia |
description |
This study provides insights into the composition and origin of ferropicrite dikes (FeOtot = 13 17 wt. %; MgO = 13 19 wt. %) and associated meimechite, picrite, picrobasalt, and basalt dikes found at Vestfjella, western Dronning Maud Land, Antarctica. The dikes crosscut Jurassic Karoo continental flood basalts (CFB) that were emplaced during the early stages of the breakup of the Gondwana supercontinent ~180 Ma ago. Selected samples (31 overall from at least eleven dikes) were analyzed for their mineral chemical, major element, trace element, and Sr, Nd, Pb, and Os isotopic compositions. The studied samples can be divided into two geochemically distinct types: (1) The depleted type (24 samples from at least nine dikes) is relatively depleted in the most incompatible elements and exhibits isotopic characteristics (e.g., initial εNd of +4.8 to +8.3 and initial 187Os/188Os of 0.1256 0.1277 at 180 Ma) similar to those of mid-ocean ridge basalts (MORB); (2) The enriched type (7 samples from at least two dikes) exhibits relatively enriched incompatible element and isotopic characteristics (e.g., initial εNd of +1.8 to +3.6 and initial 187Os/188Os of 0.1401 0.1425 at 180 Ma) similar to those of oceanic island basalts. Both magma types have escaped significant contamination by the continental crust. The depleted type is related to the main phase of Karoo magmatism and originated as highly magnesian (MgO up to 25 wt. %) partial melts at high temperatures (mantle potential temperature >1600 °C) and pressures (~5 6 GPa) from a sublithospheric, water-bearing, depleted peridotite mantle source. The enriched type sampled pyroxene-bearing heterogeneities that can be traced down to either recycled oceanic crust or melt-metasomatized portions of the sublithospheric or lithospheric mantle. The source of the depleted type represents a sublithospheric end-member source for many Karoo lavas and has subsequently been sampled by the MORBs of the Indian Ocean. These observations, together with the purported high temperatures, ... |
author2 |
Gibson, Sally University of Helsinki, Faculty of Science, Department of Geosciences and Geography, Division of Geology Helsingin yliopisto, matemaattis-luonnontieteellinen tiedekunta, geotieteiden ja maantieteen laitos Helsingfors universitet, matematisk-naturvetenskapliga fakulteten, institutionen för geovetenskaper och geografi Rämö, Tapani Luttinen, Arto |
format |
Doctoral or Postdoctoral Thesis |
author |
Heinonen, Jussi |
author_facet |
Heinonen, Jussi |
author_sort |
Heinonen, Jussi |
title |
Geochemistry and petrology of the ferropicrite dikes and associated rocks of Vestfjella, western Dronning Maud Land, Antarctica |
title_short |
Geochemistry and petrology of the ferropicrite dikes and associated rocks of Vestfjella, western Dronning Maud Land, Antarctica |
title_full |
Geochemistry and petrology of the ferropicrite dikes and associated rocks of Vestfjella, western Dronning Maud Land, Antarctica |
title_fullStr |
Geochemistry and petrology of the ferropicrite dikes and associated rocks of Vestfjella, western Dronning Maud Land, Antarctica |
title_full_unstemmed |
Geochemistry and petrology of the ferropicrite dikes and associated rocks of Vestfjella, western Dronning Maud Land, Antarctica |
title_sort |
geochemistry and petrology of the ferropicrite dikes and associated rocks of vestfjella, western dronning maud land, antarctica |
publisher |
Helsingin yliopisto |
publishDate |
2011 |
url |
http://hdl.handle.net/10138/26267 |
long_lat |
ENVELOPE(-14.000,-14.000,-73.167,-73.167) |
geographic |
Dronning Maud Land Indian Vestfjella |
geographic_facet |
Dronning Maud Land Indian Vestfjella |
genre |
Antarc* Antarctica Dronning Maud Land |
genre_facet |
Antarc* Antarctica Dronning Maud Land |
op_relation |
URN:ISBN:978-952-10-6309-1 Helsinki: 2011, Department of Geosciences and Geography A. 1798-7911 http://hdl.handle.net/10138/26267 URN:ISBN:978-952-10-6310-7 |
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_ |
1774721001398992896 |