The Architecture of a Root Zone of a Large Magmatic Conduit System From High Resolution Magnetic, Gravity and Petrophysical Data: The Reinfjord Ultramafic Complex

Z. Pastore; N. S. Church; C. Fichler; A. Michels; G. W. ter Maat; R. B. Larsen; S. A. McEnroe

doi:10.1029/2023JB027991

The Architecture of a Root Zone of a Large Magmatic Conduit System From High Resolution Magnetic, Gravity and Petrophysical Data: The Reinfjord Ultramafic Complex

Z. Pastore^*
, N. S. Church
, C. Fichler
, A. Michels
, G. W. ter Maat
, R. B. Larsen
, S. A. McEnroe

^*Corresponding author for this work

Norwegian University of Science and Technology

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

Abstract

The Seiland Igneous Province (SIP) is a large province of mafic and ultramafic (UM) complexes interpreted to be relics of a giant plumbing system feeding the Ediacaran Central Iapetus Magmatic Province. The Reinfjord Ultramafic Complex (RUC) is one of the four major ultramafic complexes of the SIP. The RUC has a younger dunite core surrounded by wehrlite and lherzolite embedded in country rocks consisting of layered gabbros with sub-horizontal layering and metamorphosed sedimentary rocks. Here, we develop a 3D subsurface model for the RUC using high-resolution magnetic and gravity data and extensive petrophysical measurements from oriented surface samples and drill core samples. Our model indicates that the RUC narrows in depth, extending a minimum of 1.4 km below sea level, and plunges eastwards below the country rock. This model allows us to decipher the lithologic heterogeneities, and the depth and lateral extent of ultramafic rocks, which we interpret in the context of the geologic history of the area. The RUC is spatially separated from other UM complexes of the SIP and the result of this study indicates a smaller depth extent. Combining these findings with the previously reported distribution of the SIP rocks based on the regional gravity data, we propose that the uplift of the crustal block hosting the RUC is larger than for ultramafic complexes in the northwestern part of the SIP.

Original language	English
Article number	e2023JB027991
Number of pages	22
Journal	Journal of Geophysical Research: Solid Earth
Volume	129
Issue number	4
DOIs	https://doi.org/10.1029/2023JB027991
Publication status	Published - Apr 2024

Bibliographical note

Publisher Copyright:
© 2024. The Authors.

Funding

This work is dedicated to Oddmund Reinfjorden who provided logistical support during the fieldwork and in numerous other expeditions to Reinfjord with professionalism and friendliness, his enthusiasm will be greatly missed. The research was funded by the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/ under REA-grant agreement No. 608001 \u201CABYSS,\u201D by the Research Council of Norway - NFR Grant 222666 to Prof. McEnroe and 324301 to Zeudia Pastore, we are grateful for the support from the NTNU department of Geoscience and Petroleum and Nordic Mining ASA, for and airborne geophysical data. The Platinum Probe project funded by the Nordic Council of Ministers to Prof. Larsen funded two of four drill cores. We greatly thank Richard Blakely, David Clark and an anonymous reviewer for their constructive comments and suggestions, and the Editor Mark Dekkers. We thank Thomas Grant, Kim Rune Grannes, Even Nikolaisen and Bjorn Eske S\u00F8rensen for field assistance. The Geological survey of Norway (NGU) provided LaCoste and Romberg G-569 gravimeter for use in fieldwork. This work is dedicated to Oddmund Reinfjorden who provided logistical support during the fieldwork and in numerous other expeditions to Reinfjord with professionalism and friendliness, his enthusiasm will be greatly missed. The research was funded by the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007\u20102013/ under REA\u2010grant agreement No. 608001 \u201CABYSS,\u201D by the Research Council of Norway \u2010 NFR Grant 222666 to Prof. McEnroe and 324301 to Zeudia Pastore, we are grateful for the support from the NTNU department of Geoscience and Petroleum and Nordic Mining ASA, for and airborne geophysical data. The Platinum Probe project funded by the Nordic Council of Ministers to Prof. Larsen funded two of four drill cores. We greatly thank Richard Blakely, David Clark and an anonymous reviewer for their constructive comments and suggestions, and the Editor Mark Dekkers. We thank Thomas Grant, Kim Rune Grannes, Even Nikolaisen and Bjorn Eske S\u00F8rensen for field assistance. The Geological survey of Norway (NGU) provided LaCoste and Romberg G\u2010569 gravimeter for use in fieldwork.

Funders	Funder number
Norges Forskningsråd
NTNU department of Geoscience and Petroleum and Nordic Mining ASA
NFR
Nordisk Ministerråd
Norges Geologiske Undersøkelse
FP7 People: Marie-Curie Actions
Seventh Framework Programme	608001
Research Council of Norway ‐ NFR	222666, 324301

Keywords

faults
gravity anomaly
magnetic anomaly
remanent magnetization
serpentinization
ultramafic rocks

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JGR Solid Earth - 2024 - Pastore - The Architecture of a Root Zone of a Large Magmatic Conduit System From High ResolutionFinal published version, 3.98 MBLicence: CC BY-NC-ND

Cite this

Pastore, Z., Church, N. S., Fichler, C., Michels, A., ter Maat, G. W., Larsen, R. B., & McEnroe, S. A. (2024). The Architecture of a Root Zone of a Large Magmatic Conduit System From High Resolution Magnetic, Gravity and Petrophysical Data: The Reinfjord Ultramafic Complex. Journal of Geophysical Research: Solid Earth, 129(4), Article e2023JB027991. https://doi.org/10.1029/2023JB027991

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title = "The Architecture of a Root Zone of a Large Magmatic Conduit System From High Resolution Magnetic, Gravity and Petrophysical Data: The Reinfjord Ultramafic Complex",

abstract = "The Seiland Igneous Province (SIP) is a large province of mafic and ultramafic (UM) complexes interpreted to be relics of a giant plumbing system feeding the Ediacaran Central Iapetus Magmatic Province. The Reinfjord Ultramafic Complex (RUC) is one of the four major ultramafic complexes of the SIP. The RUC has a younger dunite core surrounded by wehrlite and lherzolite embedded in country rocks consisting of layered gabbros with sub-horizontal layering and metamorphosed sedimentary rocks. Here, we develop a 3D subsurface model for the RUC using high-resolution magnetic and gravity data and extensive petrophysical measurements from oriented surface samples and drill core samples. Our model indicates that the RUC narrows in depth, extending a minimum of 1.4 km below sea level, and plunges eastwards below the country rock. This model allows us to decipher the lithologic heterogeneities, and the depth and lateral extent of ultramafic rocks, which we interpret in the context of the geologic history of the area. The RUC is spatially separated from other UM complexes of the SIP and the result of this study indicates a smaller depth extent. Combining these findings with the previously reported distribution of the SIP rocks based on the regional gravity data, we propose that the uplift of the crustal block hosting the RUC is larger than for ultramafic complexes in the northwestern part of the SIP.",

keywords = "faults, gravity anomaly, magnetic anomaly, remanent magnetization, serpentinization, ultramafic rocks",

author = "Z. Pastore and Church, \{N. S.\} and C. Fichler and A. Michels and \{ter Maat\}, \{G. W.\} and Larsen, \{R. B.\} and McEnroe, \{S. A.\}",

note = "Publisher Copyright: {\textcopyright} 2024. The Authors.",

year = "2024",

month = apr,

doi = "10.1029/2023JB027991",

language = "English",

volume = "129",

journal = "Journal of Geophysical Research: Solid Earth",

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Pastore, Z, Church, NS, Fichler, C, Michels, A, ter Maat, GW, Larsen, RB & McEnroe, SA 2024, 'The Architecture of a Root Zone of a Large Magmatic Conduit System From High Resolution Magnetic, Gravity and Petrophysical Data: The Reinfjord Ultramafic Complex', Journal of Geophysical Research: Solid Earth, vol. 129, no. 4, e2023JB027991. https://doi.org/10.1029/2023JB027991

The Architecture of a Root Zone of a Large Magmatic Conduit System From High Resolution Magnetic, Gravity and Petrophysical Data: The Reinfjord Ultramafic Complex. / Pastore, Z.; Church, N. S.; Fichler, C. et al.
In: Journal of Geophysical Research: Solid Earth, Vol. 129, No. 4, e2023JB027991, 04.2024.

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

TY - JOUR

T1 - The Architecture of a Root Zone of a Large Magmatic Conduit System From High Resolution Magnetic, Gravity and Petrophysical Data

T2 - The Reinfjord Ultramafic Complex

AU - Pastore, Z.

AU - Church, N. S.

AU - Fichler, C.

AU - Michels, A.

AU - ter Maat, G. W.

AU - Larsen, R. B.

AU - McEnroe, S. A.

PY - 2024/4

Y1 - 2024/4

N2 - The Seiland Igneous Province (SIP) is a large province of mafic and ultramafic (UM) complexes interpreted to be relics of a giant plumbing system feeding the Ediacaran Central Iapetus Magmatic Province. The Reinfjord Ultramafic Complex (RUC) is one of the four major ultramafic complexes of the SIP. The RUC has a younger dunite core surrounded by wehrlite and lherzolite embedded in country rocks consisting of layered gabbros with sub-horizontal layering and metamorphosed sedimentary rocks. Here, we develop a 3D subsurface model for the RUC using high-resolution magnetic and gravity data and extensive petrophysical measurements from oriented surface samples and drill core samples. Our model indicates that the RUC narrows in depth, extending a minimum of 1.4 km below sea level, and plunges eastwards below the country rock. This model allows us to decipher the lithologic heterogeneities, and the depth and lateral extent of ultramafic rocks, which we interpret in the context of the geologic history of the area. The RUC is spatially separated from other UM complexes of the SIP and the result of this study indicates a smaller depth extent. Combining these findings with the previously reported distribution of the SIP rocks based on the regional gravity data, we propose that the uplift of the crustal block hosting the RUC is larger than for ultramafic complexes in the northwestern part of the SIP.

AB - The Seiland Igneous Province (SIP) is a large province of mafic and ultramafic (UM) complexes interpreted to be relics of a giant plumbing system feeding the Ediacaran Central Iapetus Magmatic Province. The Reinfjord Ultramafic Complex (RUC) is one of the four major ultramafic complexes of the SIP. The RUC has a younger dunite core surrounded by wehrlite and lherzolite embedded in country rocks consisting of layered gabbros with sub-horizontal layering and metamorphosed sedimentary rocks. Here, we develop a 3D subsurface model for the RUC using high-resolution magnetic and gravity data and extensive petrophysical measurements from oriented surface samples and drill core samples. Our model indicates that the RUC narrows in depth, extending a minimum of 1.4 km below sea level, and plunges eastwards below the country rock. This model allows us to decipher the lithologic heterogeneities, and the depth and lateral extent of ultramafic rocks, which we interpret in the context of the geologic history of the area. The RUC is spatially separated from other UM complexes of the SIP and the result of this study indicates a smaller depth extent. Combining these findings with the previously reported distribution of the SIP rocks based on the regional gravity data, we propose that the uplift of the crustal block hosting the RUC is larger than for ultramafic complexes in the northwestern part of the SIP.

KW - faults

KW - gravity anomaly

KW - magnetic anomaly

KW - remanent magnetization

KW - serpentinization

KW - ultramafic rocks

UR - https://www.scopus.com/pages/publications/85190368800

U2 - 10.1029/2023JB027991

DO - 10.1029/2023JB027991

M3 - Article

AN - SCOPUS:85190368800

SN - 2169-9313

VL - 129

JO - Journal of Geophysical Research: Solid Earth

JF - Journal of Geophysical Research: Solid Earth

IS - 4

M1 - e2023JB027991

ER -

The Architecture of a Root Zone of a Large Magmatic Conduit System From High Resolution Magnetic, Gravity and Petrophysical Data: The Reinfjord Ultramafic Complex

Abstract

Bibliographical note

Funding

Keywords

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