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Marine geophysical investigation of the Chain Fracture Zone in the equatorial Atlantic from the PI‐LAB experiment

Marine geophysical investigation of the Chain Fracture Zone in the equatorial Atlantic from the PI‐LAB experiment
Marine geophysical investigation of the Chain Fracture Zone in the equatorial Atlantic from the PI‐LAB experiment
The Chain Fracture Zone is a 300 km long transform fault that offsets the Mid Atlantic Ridge. We analysed new multibeam bathymetry, backscatter, gravity and magnetic data with 100 % multibeam bathymetric data over the active transform valley and adjacent spreading segments as part of the Passive Imaging of the Lithosphere Asthenosphere Boundary (PI‐LAB) Experiment. Analyses of these data sets allow us to determine the history and mode of crustal formation and the tectonic evolution of the transform system and adjacent ridges over the past 20 M.y. We model the total field magnetic anomaly to determine the age of the crust along the northern ridge segment to better establish the timing of the variations in the seafloor fabric and the tectonic‐magmatic history of the region. Within the active transform fault zone, we observe 4 distinct positive flower structures with several en échelon fault scarps visible in the backscatter data. We find up to ‐10 mGal residual Mantle Bouguer Anomaly in the region of the largest positive flower structure within the transform zone suggesting crustal thickening relative to the crustal thinning typically observed in fracture zones in the Atlantic. The extensional/compressional features observed in the Chain Transform are less pronounced than those observed further north in the Vema, St Paul and Romanche and may be due to local ridge segment adjustments.
2169-9356
11016-11030
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Agius, Matthew
cb168c8d-0926-4c0d-951c-721fb4cf1ebf
Tharimena, Saikiran
9e95dff0-7044-43d4-ac5e-51e72468b719
Le Bas, Tim P.
4128286d-8730-4ee8-ba45-2d55b3962701
Kendall, J. Michael
49233af5-e888-4ab8-87b7-d97938f0ed27
Constable, Steven
f2ffd9c4-3738-435b-8a88-38dee97de7cc
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Agius, Matthew
cb168c8d-0926-4c0d-951c-721fb4cf1ebf
Tharimena, Saikiran
9e95dff0-7044-43d4-ac5e-51e72468b719
Le Bas, Tim P.
4128286d-8730-4ee8-ba45-2d55b3962701
Kendall, J. Michael
49233af5-e888-4ab8-87b7-d97938f0ed27
Constable, Steven
f2ffd9c4-3738-435b-8a88-38dee97de7cc

Harmon, Nicholas, Rychert, Catherine, Agius, Matthew, Tharimena, Saikiran, Le Bas, Tim P., Kendall, J. Michael and Constable, Steven (2018) Marine geophysical investigation of the Chain Fracture Zone in the equatorial Atlantic from the PI‐LAB experiment. Journal of Geophysical Research: Solid Earth, 123 (12), 11016-11030. (doi:10.1029/2018JB015982).

Record type: Article

Abstract

The Chain Fracture Zone is a 300 km long transform fault that offsets the Mid Atlantic Ridge. We analysed new multibeam bathymetry, backscatter, gravity and magnetic data with 100 % multibeam bathymetric data over the active transform valley and adjacent spreading segments as part of the Passive Imaging of the Lithosphere Asthenosphere Boundary (PI‐LAB) Experiment. Analyses of these data sets allow us to determine the history and mode of crustal formation and the tectonic evolution of the transform system and adjacent ridges over the past 20 M.y. We model the total field magnetic anomaly to determine the age of the crust along the northern ridge segment to better establish the timing of the variations in the seafloor fabric and the tectonic‐magmatic history of the region. Within the active transform fault zone, we observe 4 distinct positive flower structures with several en échelon fault scarps visible in the backscatter data. We find up to ‐10 mGal residual Mantle Bouguer Anomaly in the region of the largest positive flower structure within the transform zone suggesting crustal thickening relative to the crustal thinning typically observed in fracture zones in the Atlantic. The extensional/compressional features observed in the Chain Transform are less pronounced than those observed further north in the Vema, St Paul and Romanche and may be due to local ridge segment adjustments.

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Accepted/In Press date: 10 November 2018
e-pub ahead of print date: 16 November 2018
Published date: December 2018

Identifiers

Local EPrints ID: 426861
URI: http://eprints.soton.ac.uk/id/eprint/426861
ISSN: 2169-9356
PURE UUID: 9f8b54ce-1c9d-4fad-9d22-71975455c01d
ORCID for Nicholas Harmon: ORCID iD orcid.org/0000-0002-0731-768X
ORCID for Saikiran Tharimena: ORCID iD orcid.org/0000-0002-1841-1911

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Date deposited: 14 Dec 2018 17:30
Last modified: 07 Oct 2020 02:14

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