Link between SSZ ophiolite formation, emplacement and arc inception, Northland, New Zealand: U-Pb SHRIMP constraints; Cenozoic SW Pacific tectonic implications

Scott A. Whattam; John Malpas; Ian E.M. Smith; Jason R. Ali

doi:10.1016/j.epsl.2006.07.047

Link between SSZ ophiolite formation, emplacement and arc inception, Northland, New Zealand: U-Pb SHRIMP constraints; Cenozoic SW Pacific tectonic implications

Scott A. Whattam^*, John Malpas, Ian E.M. Smith, Jason R. Ali

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

51 Scopus citations

Abstract

New U-Pb age-data from zircons separated from a Northland ophiolite gabbro yield a mean ²⁰⁶Pb/²³⁸U age of 31.6 ± 0.2 Ma, providing support for a recently determined 28.3 ± 0.2 Ma SHRIMP age of an associated plagiogranite and ∼ 29-26 Ma ⁴⁰Ar/³⁹Ar ages (n = 9) of basalts of the ophiolite. Elsewhere, Miocene arc-related calc-alkaline andesite dikes which intrude the ophiolitic rocks contain zircons which yield mean ²⁰⁶Pb/²³⁸U ages of 20.1 ± 0.2 and 19.8 ± 0.2 Ma. The ophiolite gabbro and the andesites both contain rare inherited zircons ranging from 122-104 Ma. The Early Cretaceous zircons in the arc andesites are interpreted as xenocrysts from the Mt. Camel basement terrane through which magmas of the Northland Miocene arc lavas erupted. The inherited zircons in the ophiolite gabbros suggest that a small fraction of this basement was introduced into the suboceanic mantle by subduction and mixed with mantle melts during ophiolite formation. We postulate that the tholeiitic suite of the ophiolite represents the crustal segment of SSZ lithosphere (SSZL) generated in the southern South Fiji Basin (SFB) at a northeast-dipping subduction zone that was initiated at about 35 Ma. The subduction zone nucleated along a pre-existing transform boundary separating circa 45-20 Ma oceanic lithosphere to the north and west of the Northland Peninsula from nascent back arc basin lithosphere of the SFB. Construction of the SSZL propagated southward along the transform boundary as the SFB continued to unzip to the southeast. After subduction of a large portion of oceanic lithosphere by about 26 Ma and collision of the SSZL with New Zealand, compression between the Australian Plate and the Pacific Plate was taken up along a new southwest-dipping subduction zone behind the SSZL. Renewed volcanism began in the oceanic forearc at 25 Ma producing boninitic-like, SSZ and within-plate alkalic and calc-alkaline rocks. Rocks of these types temporally overlap ophiolite emplacement and subsequent Miocene continental arc construction.

Original language	English
Pages (from-to)	606-632
Number of pages	27
Journal	Earth and Planetary Science Letters
Volume	250
Issue number	3-4
DOIs	https://doi.org/10.1016/j.epsl.2006.07.047
State	Published - 30 Oct 2006
Externally published	Yes

Bibliographical note

Funding Information:
Insightful and helpful suggestions from an anonymous reviewer improved the original manuscript. We would like to thank N. Rayner for zircon sample preparation and W. J. Davis for operation of the SHRIMP II at the J. C. Roddick Ion Microprobe laboratory, Geological Survey of Canada (GSC), Ottawa. X. Zhou and F. Mak of the Department of Earth Sciences at The University of Hong Kong are thanked for the XRF and ICP-MS analyses, respectively. This work was funded by a HK CERG grant award (HKU 7017/03P) to JM and a postdoctoral fellowship to SAW through the BK 21 grant to the Petrotectonics Laboratory, School of Earth and Environmental Sciences (SEES), Seoul National University.

Keywords

Northland arc
Northland ophiolite
SHRIMP
SSZ lithosphere (SSZL)
SW Pacific
South Fiji Basin

ASJC Scopus subject areas

Geophysics
Geochemistry and Petrology
Earth and Planetary Sciences (miscellaneous)
Space and Planetary Science

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1016/j.epsl.2006.07.047

Cite this

@article{c571a5c523144b7dadffc60b45643ee1,

title = "Link between SSZ ophiolite formation, emplacement and arc inception, Northland, New Zealand: U-Pb SHRIMP constraints; Cenozoic SW Pacific tectonic implications",

abstract = "New U-Pb age-data from zircons separated from a Northland ophiolite gabbro yield a mean 206Pb/238U age of 31.6 ± 0.2 Ma, providing support for a recently determined 28.3 ± 0.2 Ma SHRIMP age of an associated plagiogranite and ∼ 29-26 Ma 40Ar/39Ar ages (n = 9) of basalts of the ophiolite. Elsewhere, Miocene arc-related calc-alkaline andesite dikes which intrude the ophiolitic rocks contain zircons which yield mean 206Pb/238U ages of 20.1 ± 0.2 and 19.8 ± 0.2 Ma. The ophiolite gabbro and the andesites both contain rare inherited zircons ranging from 122-104 Ma. The Early Cretaceous zircons in the arc andesites are interpreted as xenocrysts from the Mt. Camel basement terrane through which magmas of the Northland Miocene arc lavas erupted. The inherited zircons in the ophiolite gabbros suggest that a small fraction of this basement was introduced into the suboceanic mantle by subduction and mixed with mantle melts during ophiolite formation. We postulate that the tholeiitic suite of the ophiolite represents the crustal segment of SSZ lithosphere (SSZL) generated in the southern South Fiji Basin (SFB) at a northeast-dipping subduction zone that was initiated at about 35 Ma. The subduction zone nucleated along a pre-existing transform boundary separating circa 45-20 Ma oceanic lithosphere to the north and west of the Northland Peninsula from nascent back arc basin lithosphere of the SFB. Construction of the SSZL propagated southward along the transform boundary as the SFB continued to unzip to the southeast. After subduction of a large portion of oceanic lithosphere by about 26 Ma and collision of the SSZL with New Zealand, compression between the Australian Plate and the Pacific Plate was taken up along a new southwest-dipping subduction zone behind the SSZL. Renewed volcanism began in the oceanic forearc at 25 Ma producing boninitic-like, SSZ and within-plate alkalic and calc-alkaline rocks. Rocks of these types temporally overlap ophiolite emplacement and subsequent Miocene continental arc construction.",

keywords = "Northland arc, Northland ophiolite, SHRIMP, SSZ lithosphere (SSZL), SW Pacific, South Fiji Basin",

author = "Whattam, \{Scott A.\} and John Malpas and Smith, \{Ian E.M.\} and Ali, \{Jason R.\}",

note = "Funding Information: Insightful and helpful suggestions from an anonymous reviewer improved the original manuscript. We would like to thank N. Rayner for zircon sample preparation and W. J. Davis for operation of the SHRIMP II at the J. C. Roddick Ion Microprobe laboratory, Geological Survey of Canada (GSC), Ottawa. X. Zhou and F. Mak of the Department of Earth Sciences at The University of Hong Kong are thanked for the XRF and ICP-MS analyses, respectively. This work was funded by a HK CERG grant award (HKU 7017/03P) to JM and a postdoctoral fellowship to SAW through the BK 21 grant to the Petrotectonics Laboratory, School of Earth and Environmental Sciences (SEES), Seoul National University.",

year = "2006",

month = oct,

day = "30",

doi = "10.1016/j.epsl.2006.07.047",

language = "English",

volume = "250",

pages = "606--632",

journal = "Earth and Planetary Science Letters",

issn = "0012-821X",

publisher = "Elsevier B.V.",

number = "3-4",

}

Link between SSZ ophiolite formation, emplacement and arc inception, Northland, New Zealand: U-Pb SHRIMP constraints; Cenozoic SW Pacific tectonic implications. / Whattam, Scott A.; Malpas, John; Smith, Ian E.M. et al.
In: Earth and Planetary Science Letters, Vol. 250, No. 3-4, 30.10.2006, p. 606-632.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Link between SSZ ophiolite formation, emplacement and arc inception, Northland, New Zealand

T2 - U-Pb SHRIMP constraints; Cenozoic SW Pacific tectonic implications

AU - Whattam, Scott A.

AU - Malpas, John

AU - Smith, Ian E.M.

AU - Ali, Jason R.

N1 - Funding Information: Insightful and helpful suggestions from an anonymous reviewer improved the original manuscript. We would like to thank N. Rayner for zircon sample preparation and W. J. Davis for operation of the SHRIMP II at the J. C. Roddick Ion Microprobe laboratory, Geological Survey of Canada (GSC), Ottawa. X. Zhou and F. Mak of the Department of Earth Sciences at The University of Hong Kong are thanked for the XRF and ICP-MS analyses, respectively. This work was funded by a HK CERG grant award (HKU 7017/03P) to JM and a postdoctoral fellowship to SAW through the BK 21 grant to the Petrotectonics Laboratory, School of Earth and Environmental Sciences (SEES), Seoul National University.

PY - 2006/10/30

Y1 - 2006/10/30

N2 - New U-Pb age-data from zircons separated from a Northland ophiolite gabbro yield a mean 206Pb/238U age of 31.6 ± 0.2 Ma, providing support for a recently determined 28.3 ± 0.2 Ma SHRIMP age of an associated plagiogranite and ∼ 29-26 Ma 40Ar/39Ar ages (n = 9) of basalts of the ophiolite. Elsewhere, Miocene arc-related calc-alkaline andesite dikes which intrude the ophiolitic rocks contain zircons which yield mean 206Pb/238U ages of 20.1 ± 0.2 and 19.8 ± 0.2 Ma. The ophiolite gabbro and the andesites both contain rare inherited zircons ranging from 122-104 Ma. The Early Cretaceous zircons in the arc andesites are interpreted as xenocrysts from the Mt. Camel basement terrane through which magmas of the Northland Miocene arc lavas erupted. The inherited zircons in the ophiolite gabbros suggest that a small fraction of this basement was introduced into the suboceanic mantle by subduction and mixed with mantle melts during ophiolite formation. We postulate that the tholeiitic suite of the ophiolite represents the crustal segment of SSZ lithosphere (SSZL) generated in the southern South Fiji Basin (SFB) at a northeast-dipping subduction zone that was initiated at about 35 Ma. The subduction zone nucleated along a pre-existing transform boundary separating circa 45-20 Ma oceanic lithosphere to the north and west of the Northland Peninsula from nascent back arc basin lithosphere of the SFB. Construction of the SSZL propagated southward along the transform boundary as the SFB continued to unzip to the southeast. After subduction of a large portion of oceanic lithosphere by about 26 Ma and collision of the SSZL with New Zealand, compression between the Australian Plate and the Pacific Plate was taken up along a new southwest-dipping subduction zone behind the SSZL. Renewed volcanism began in the oceanic forearc at 25 Ma producing boninitic-like, SSZ and within-plate alkalic and calc-alkaline rocks. Rocks of these types temporally overlap ophiolite emplacement and subsequent Miocene continental arc construction.

AB - New U-Pb age-data from zircons separated from a Northland ophiolite gabbro yield a mean 206Pb/238U age of 31.6 ± 0.2 Ma, providing support for a recently determined 28.3 ± 0.2 Ma SHRIMP age of an associated plagiogranite and ∼ 29-26 Ma 40Ar/39Ar ages (n = 9) of basalts of the ophiolite. Elsewhere, Miocene arc-related calc-alkaline andesite dikes which intrude the ophiolitic rocks contain zircons which yield mean 206Pb/238U ages of 20.1 ± 0.2 and 19.8 ± 0.2 Ma. The ophiolite gabbro and the andesites both contain rare inherited zircons ranging from 122-104 Ma. The Early Cretaceous zircons in the arc andesites are interpreted as xenocrysts from the Mt. Camel basement terrane through which magmas of the Northland Miocene arc lavas erupted. The inherited zircons in the ophiolite gabbros suggest that a small fraction of this basement was introduced into the suboceanic mantle by subduction and mixed with mantle melts during ophiolite formation. We postulate that the tholeiitic suite of the ophiolite represents the crustal segment of SSZ lithosphere (SSZL) generated in the southern South Fiji Basin (SFB) at a northeast-dipping subduction zone that was initiated at about 35 Ma. The subduction zone nucleated along a pre-existing transform boundary separating circa 45-20 Ma oceanic lithosphere to the north and west of the Northland Peninsula from nascent back arc basin lithosphere of the SFB. Construction of the SSZL propagated southward along the transform boundary as the SFB continued to unzip to the southeast. After subduction of a large portion of oceanic lithosphere by about 26 Ma and collision of the SSZL with New Zealand, compression between the Australian Plate and the Pacific Plate was taken up along a new southwest-dipping subduction zone behind the SSZL. Renewed volcanism began in the oceanic forearc at 25 Ma producing boninitic-like, SSZ and within-plate alkalic and calc-alkaline rocks. Rocks of these types temporally overlap ophiolite emplacement and subsequent Miocene continental arc construction.

KW - Northland arc

KW - Northland ophiolite

KW - SHRIMP

KW - SSZ lithosphere (SSZL)

KW - SW Pacific

KW - South Fiji Basin

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U2 - 10.1016/j.epsl.2006.07.047

DO - 10.1016/j.epsl.2006.07.047

M3 - Article

AN - SCOPUS:33749444132

SN - 0012-821X

VL - 250

SP - 606

EP - 632

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

IS - 3-4

ER -

Link between SSZ ophiolite formation, emplacement and arc inception, Northland, New Zealand: U-Pb SHRIMP constraints; Cenozoic SW Pacific tectonic implications

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

UN SDGs

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