Age distribution of Ocean Drill sites across the Central Walvis Ridge indicates plate boundary control of plume volcanism in the South Atlantic

O’Connor, John; Jokat, Wilfried

doi:10.1016/j.epsl.2015.05.021

Cited by 33 publications

(42 citation statements)

References 59 publications

(132 reference statements)

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“…Updated magnetic anomalies support the hypothesis of a MAR reorganization in which a large transform offset north of WR during the Cretaceous Quiet Period evolved southward into to multiple small transform offsets by anomaly C30n, resulting in the formation of several new transform faults south of~30°S. Magnetic anomalies C34n, C33r, and C32n.1n display trends that follow WR bathymetry, supporting the idea that spreading ridge-hot spot interaction largely controlled WR morphology ( Figure S10; O'Connor & Jokat, 2015aJokat, , 2015b. Updated anomalies show irregular geometry and spacing between isochrons C33y-C34n, with the width of anomalies C33r-C34n near WR narrowing southward.…”

Section: Discussionsupporting

confidence: 59%

“…WR begins offshore of Africa as a narrow ridge (Frio Ridge) near the continental margin, continues as an oceanic plateau (Valdivia Bank) at right angles, changes to a series of N‐S trending ridges (Central WR), and splits into three distinct seamount chains (Guyot Province; Figure ). In response, authors have resorted to models with multiple hot spots (O'Connor & le Roex, ), moving hot spots (Doubrovine et al, ), and hot spot‐ridge interaction (O'Connor & Jokat, , ) to explain WR morphologic changes.…”

Section: Introductionmentioning

confidence: 99%

“…WR is a southwest trending submarine ridge extending from the coast of Namibia to the islands of Tristan and Gough, near the Mid-Atlantic Ridge (MAR), whereas RGR is a submarine plateau east of Brazil. During the Late Cretaceous, the old WR (Frio Ridge, Valdivia Bank and Central WR) and main RGR (RGR Massif) were emplaced at or near the MAR axis by a hot spot (Morgan, 1981;O'Connor & Duncan, 1990;O'Connor & Jokat, 2015a). About~60-70 Ma, the MAR moved away from the hot spot, with the result that RGR formation ceased and three seamount chains were formed on the African plate, with volcanism continuing to the present (O'Connor & Duncan, 1990;O'Connor & Jokat, 2015a;Rohde et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…WR begins offshore of Africa as a narrow ridge (Frio Ridge) near the continental margin, continues as an oceanic plateau (Valdivia Bank) at right ©2019 angles, changes to a series of N-S trending ridges (Central WR), and splits into three distinct seamount chains (Guyot Province; Figure 1). In response, authors have resorted to models with multiple hot spots (O'Connor & le Roex, 1992), moving hot spots (Doubrovine et al, 2012), and hot spot-ridge interaction (O'Connor & Jokat, 2015a, 2015b Figure S1 in the supporting information). Coincidently, there was a reduction of spreading rate from~70 mm/year (end of C34) to~40 mm/year (end of C30), several new FZs formed between WR and RGR and eastward ridge jumps occurred (Cande et al, 1988;Sager et al, submitted).…”

Section: Introductionmentioning

confidence: 99%

“…WR is mostly a linear ridge but changes character along its length, whereas RGR consists of two subrounded plateaus (RGR Massif and SE‐RGR) and a spreading‐axis parallel ridge (E‐RGR; Figure ). O'Connor and Jokat (, ) attribute changes of WR morphology to the interaction of the hot spot and MAR and their divergence during the Cenozoic.…”

Section: Introductionmentioning

confidence: 99%

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Implications of Updated Magnetic Anomalies for the Late Cretaceous Tectonic Evolution of Walvis Ridge

Thoram

Sager

Jokat

2019

Geophysical Research Letters

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In the South Atlantic, a reorganization of the Mid‐Atlantic Ridge began before anomaly C34n (83.6 Ma) and ended before anomaly C30n (66.4 Ma), complicating tectonics of Rio Grande Rise and older Walvis Ridge (WR), which formed together at the Mid‐Atlantic Ridge. This reorganization is poorly understood because magnetic anomalies C30n‐C34n are poorly defined near WR. We interpreted these anomalies along western WR to improve knowledge of Rio Grande Rise‐WR tectonic development. Anomaly trends indicate that Valdivia Bank has an E‐W age progression, perpendicular to that predicted by hot spot models. Anomaly spacing and width is irregular and anomalous near WR, implying a series of ridge jumps and possibly a microplate between anomalies C34n and C32n. Eastward ridge jumps transferred microplate lithosphere to the South American plate. This study shows that Late Cretaceous tectonic evolution of the Rio Grande Rise‐WR large igneous provinces was more complex than previously understood.

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Section: Discussionsupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Implications of Updated Magnetic Anomalies for the Late Cretaceous Tectonic Evolution of Walvis Ridge

Thoram

Sager

Jokat

2019

Geophysical Research Letters

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Major influence of plume‐ridge interaction, lithosphere thickness variations, and global mantle flow on hotspot volcanism—The example of Tristan

Gassmöller

Dannberg

Bredow

et al. 2016

Geochem Geophys Geosyst

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Hotspot tracks are thought to originate when mantle plumes impinge moving plates. However, many observed cases close to mid-ocean ridges do not form a single age-progressive line, but vary in width, are separated into several volcanic chains, or are distributed over different plates. Here we study plume-ridge interaction at the example of the Tristan plume, which features all of these complexities. Additionally, the South Atlantic formed close to where plume volcanism began, opening from the south and progressing northward with a notable decrease in magmatism across the Florianopolis Fracture Zone. We study the full evolution of the Tristan plume in a series of three-dimensional regional models created with the convection code ASPECT. We then compute crustal thickness maps and compare them to seismic profiles and the topography of the South Atlantic. We find that the separation of volcanism into the Tristan and Gough chain can be explained by the position of the plume relative to the ridge and the influence of the global flow field. Plume material below the off-ridge track can flow toward the ridge and regions of thinner lithosphere, where decompression melting leads to the development of a second volcanic chain resembling the Tristan and Gough hotspot tracks. Agreement with the observations is best for a small plume buoyancy flux of 500 kg/s or a low excess temperature of 150 K. The model explains the distribution of syn-rift magmatism by hot plume material that flows into the rift and increases melt generation.

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Möwe Bay Dykes, Northwestern Namibia: Geochemical and geochronological evidence for different mantle source regions during the Cretaceous opening of the South Atlantic

2016

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Age distribution of Ocean Drill sites across the Central Walvis Ridge indicates plate boundary control of plume volcanism in the South Atlantic

Cited by 33 publications

References 59 publications

Implications of Updated Magnetic Anomalies for the Late Cretaceous Tectonic Evolution of Walvis Ridge

Implications of Updated Magnetic Anomalies for the Late Cretaceous Tectonic Evolution of Walvis Ridge

Major influence of plume‐ridge interaction, lithosphere thickness variations, and global mantle flow on hotspot volcanism—The example of Tristan

Möwe Bay Dykes, Northwestern Namibia: Geochemical and geochronological evidence for different mantle source regions during the Cretaceous opening of the South Atlantic

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