Geochemistry of the North Cape mafic-ultramafic complex : an arc-type primitive magma intrusion, northeastern most New Zealand
The North Cape Mafic-Ultramafic Complex is an 8 km2 igneous massif at the northeastern tip of the North Island of New Zealand consisting of mafic and ultramafic phaneritic intrusions, some of which are cumulates. It was originally thought to represent the lowest levels of a Late Cretaceous-Paleocene...
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ftballstcs:oai:cardinalscholar.bsu.edu:123456789/199250 2023-05-15T17:37:54+02:00 Geochemistry of the North Cape mafic-ultramafic complex : an arc-type primitive magma intrusion, northeastern most New Zealand Lange, Eric S. Nicholson, Kirsten N. 2014-12-13 http://cardinalscholar.bsu.edu/handle/123456789/199250 http://liblink.bsu.edu/catkey/1780474 unknown http://cardinalscholar.bsu.edu/handle/123456789/199250 http://liblink.bsu.edu/catkey/1780474 Geochemistry -- New Zealand -- Northland Ultrabasic rocks -- New Zealand -- Northland Magmas -- New Zealand -- Northland Geology Stratigraphic -- Miocene 2014 ftballstcs 2022-05-30T13:30:59Z The North Cape Mafic-Ultramafic Complex is an 8 km2 igneous massif at the northeastern tip of the North Island of New Zealand consisting of mafic and ultramafic phaneritic intrusions, some of which are cumulates. It was originally thought to represent the lowest levels of a Late Cretaceous-Paleocene ophiolite sequence known as the Northland Allochthon. The Tangihua Complex, the volcanic components of the Northland Allochthon has a geochemical signature indicating that it formed in a supra-subduction zone. These lavas have been hydrothermally altered to up to greenschist facies from obduction in the Oligocene. The mafic and ultramafic intrusions at North Cape display only minor, low-grade clay alteration, inconsistent with the rest of the Northland Allochthon. Whole rock geochemistry from this study shows that the intrusions at North Cape have an island-arc signature in clear contrast with the supra-subduction zone signature of the Tangihua Complex. This suggests that the intrusions at North Cape are more related to the Miocene-aged Northland Volcanic Arc. Geochemical modeling confirms this relationship; the Northland Volcanic Arc series can be produced from between three and forty-six percent fraction of the North Cape magma. The North Cape intrusions contain very high amounts of the mantle compatible elements of Mg, Cr, and Ni, indicating that they are a type of primitive magma. This finding, along with the newly determined relationship with the Northland Volcanic Arc means that North Cape intrusions represent a composition very close to the original subduction generated magma chamber that produced the Miocene-aged arc volcanism that has migrated southwest down the North Island and continues at its current location at the Taupo Volcanic Zone. Department of Geological Sciences Geologic setting -- Methods -- Sample locations -- Petrography -- Geochemistry -- Geochemical relationships -- Geochemical modeling -- North Cape's primitive magmas. Thesis (M.S.) Other/Unknown Material North Cape Ball State University: Cardinal Scholar New Zealand North Cape ENVELOPE(165.700,165.700,-70.650,-70.650) |
institution |
Open Polar |
collection |
Ball State University: Cardinal Scholar |
op_collection_id |
ftballstcs |
language |
unknown |
topic |
Geochemistry -- New Zealand -- Northland Ultrabasic rocks -- New Zealand -- Northland Magmas -- New Zealand -- Northland Geology Stratigraphic -- Miocene |
spellingShingle |
Geochemistry -- New Zealand -- Northland Ultrabasic rocks -- New Zealand -- Northland Magmas -- New Zealand -- Northland Geology Stratigraphic -- Miocene Lange, Eric S. Geochemistry of the North Cape mafic-ultramafic complex : an arc-type primitive magma intrusion, northeastern most New Zealand |
topic_facet |
Geochemistry -- New Zealand -- Northland Ultrabasic rocks -- New Zealand -- Northland Magmas -- New Zealand -- Northland Geology Stratigraphic -- Miocene |
description |
The North Cape Mafic-Ultramafic Complex is an 8 km2 igneous massif at the northeastern tip of the North Island of New Zealand consisting of mafic and ultramafic phaneritic intrusions, some of which are cumulates. It was originally thought to represent the lowest levels of a Late Cretaceous-Paleocene ophiolite sequence known as the Northland Allochthon. The Tangihua Complex, the volcanic components of the Northland Allochthon has a geochemical signature indicating that it formed in a supra-subduction zone. These lavas have been hydrothermally altered to up to greenschist facies from obduction in the Oligocene. The mafic and ultramafic intrusions at North Cape display only minor, low-grade clay alteration, inconsistent with the rest of the Northland Allochthon. Whole rock geochemistry from this study shows that the intrusions at North Cape have an island-arc signature in clear contrast with the supra-subduction zone signature of the Tangihua Complex. This suggests that the intrusions at North Cape are more related to the Miocene-aged Northland Volcanic Arc. Geochemical modeling confirms this relationship; the Northland Volcanic Arc series can be produced from between three and forty-six percent fraction of the North Cape magma. The North Cape intrusions contain very high amounts of the mantle compatible elements of Mg, Cr, and Ni, indicating that they are a type of primitive magma. This finding, along with the newly determined relationship with the Northland Volcanic Arc means that North Cape intrusions represent a composition very close to the original subduction generated magma chamber that produced the Miocene-aged arc volcanism that has migrated southwest down the North Island and continues at its current location at the Taupo Volcanic Zone. Department of Geological Sciences Geologic setting -- Methods -- Sample locations -- Petrography -- Geochemistry -- Geochemical relationships -- Geochemical modeling -- North Cape's primitive magmas. Thesis (M.S.) |
author2 |
Nicholson, Kirsten N. |
author |
Lange, Eric S. |
author_facet |
Lange, Eric S. |
author_sort |
Lange, Eric S. |
title |
Geochemistry of the North Cape mafic-ultramafic complex : an arc-type primitive magma intrusion, northeastern most New Zealand |
title_short |
Geochemistry of the North Cape mafic-ultramafic complex : an arc-type primitive magma intrusion, northeastern most New Zealand |
title_full |
Geochemistry of the North Cape mafic-ultramafic complex : an arc-type primitive magma intrusion, northeastern most New Zealand |
title_fullStr |
Geochemistry of the North Cape mafic-ultramafic complex : an arc-type primitive magma intrusion, northeastern most New Zealand |
title_full_unstemmed |
Geochemistry of the North Cape mafic-ultramafic complex : an arc-type primitive magma intrusion, northeastern most New Zealand |
title_sort |
geochemistry of the north cape mafic-ultramafic complex : an arc-type primitive magma intrusion, northeastern most new zealand |
publishDate |
2014 |
url |
http://cardinalscholar.bsu.edu/handle/123456789/199250 http://liblink.bsu.edu/catkey/1780474 |
long_lat |
ENVELOPE(165.700,165.700,-70.650,-70.650) |
geographic |
New Zealand North Cape |
geographic_facet |
New Zealand North Cape |
genre |
North Cape |
genre_facet |
North Cape |
op_relation |
http://cardinalscholar.bsu.edu/handle/123456789/199250 http://liblink.bsu.edu/catkey/1780474 |
_version_ |
1766138122359275520 |