Preserved extent of Jurassic flood basalt in the South Georgia Rift: A new interpretation of the J horizon

Heffner, David M.; Knapp, J. H.; Akintunde, Olusoga M.; Knapp, C. C.

doi:10.1130/g32638.1

Cited by 23 publications

(21 citation statements)

References 11 publications

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“…-In this reconstruction, the formation of the volcanoes from the Guinea Fracture Zone (Carter, Krause, Nadir) is not directly related to the hotspot, being> 500 km far from it during their formation (54)(55)(56)(57)(58)(59).…”

Section: Kinematic Reconstructionmentioning

confidence: 86%

“…Burke and Torsvik 2 and Ruiz-Martinez et al 53 previously noticed this coincidence between reconstructed locations of the Sierra Leone hotspot and the CAMP. Although the age of the SDRs from the Carolina trough and the Blake Plateau is debated 54 , they appear to pre-date the onset of oceanic spreading, circa 190 Ma 8 . Hence a single hotspot may have formed successive sets of SDRs during the southward propagation of the Central Atlantic, from 200-190 Ma along the east coast of North America to 180-170 Ma in Demerara, at the southernmost tip of the Central Atlantic.…”

Section: Discussionmentioning

confidence: 99%

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The Jurassic magmatism of the Demerara Plateau (offshore French Guiana) as a remnant of the Sierra Leone hotspot during the Atlantic rifting

Basile

Girault

Paquette

et al. 2020

Sci Rep

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We report the discovery of 173.4 Ma hotspot-related magmatic rocks in the basement of the Demerara Plateau, offshore French Guiana and Suriname. According to plate reconstructions, a single hotspot may be responsible for the magmatic formation of (1) both the Demerara Plateau (between 180 and 170 Ma) and the Guinea Plateau (circa 165 Ma) during the end of the Jurassic rifting of the Central Atlantic; (2) both Sierra Leone and Ceara Rises (mainly from 76 to 68 Ma) during the upper Cretaceous oceanic spreading of the Equatorial Atlantic ocean; (3) the Bathymetrists seamount chain since the upper Cretaceous. The present-day location of the inferred Sierra Leone hotspot should be 100 km west of the Knipovich Seamount.

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Section: Kinematic Reconstructionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

The Jurassic magmatism of the Demerara Plateau (offshore French Guiana) as a remnant of the Sierra Leone hotspot during the Atlantic rifting

Basile

Girault

Paquette

et al. 2020

Sci Rep

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“…The South Georgia Rift has voluminous buried mafic dikes and sills based on drilling [ Chowns and Williams , ] and seismic reflection profiling [e.g., McBride et al , ; Austin et al , ; Oh et al , ]. (The precise extent of CAMP in the southeastern U.S. is uncertain given recent reinterpretation of seismic data by Heffner et al []). Although the origin of the thermal event producing CAMP is uncertain [e.g., White and McKenzie , ; Gurnis , ; Coltice et al , ; Anderson , ], we suggest that within the South Georgia Rift it compositionally modified and/or eroded the lower lithosphere.…”

Section: Discussionmentioning

confidence: 99%

Seismic velocity structure of the crust and shallow mantle of the Central and Eastern United States by seismic surface wave imaging

Pollitz

Mooney

2016

Geophysical Research Letters

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Seismic surface waves from the Transportable Array of EarthScope's USArray are used to estimate phase velocity structure of 18 to 125 s Rayleigh waves, then inverted to obtain three‐dimensional crust and upper mantle structure of the Central and Eastern United States (CEUS) down to ∼200 km. The obtained lithosphere structure confirms previously imaged CEUS features, e.g., the low seismic‐velocity signature of the Cambrian Reelfoot Rift and the very low velocity at >150 km depth below an Eocene volcanic center in northwestern Virginia. New features include high‐velocity mantle stretching from the Archean Superior Craton well into the Proterozoic terranes and deep low‐velocity zones in central Texas (associated with the late Cretaceous Travis and Uvalde volcanic fields) and beneath the South Georgia Rift (which contains Jurassic basalts). Hot spot tracks may be associated with several imaged low‐velocity zones, particularly those close to the former rifted Laurentia margin.

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“…Rifting occurred~40-50 Ma after the Late Paleozoic collision of Suwannee terranes with Laurentia, and it likely reactivated this lithospheric boundary [Harry and Londono, 2004;Thomas, 2011]. CAMP-aged volcanics in the nearby SGRB and Suwannee terrane of Florida also indicate elevated mantle temperatures during the onset of Gulf rifting [McBride, 1991;Heatherington and Mueller, 2003;Heffner et al, 2012]. Our observations of HVLC and probable volcanism in the Apalachicola Basin are consistent with volcanic rifted margins offshore southwestern Morocco and at the Rockall Trough offshore Scotland [Klingelhöefer et al, 2005[Klingelhöefer et al, , 2009] and support high mantle potential temperatures during rifting in the northeastern Gulf of Mexico.…”

Section: Rifted Crustmentioning

confidence: 99%

Deep crustal structure of the northeastern Gulf of Mexico: Implications for rift evolution and seafloor spreading

et al. 2014

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We image deep crustal structure using marine seismic refraction data recorded by a linear array of ocean-bottom seismometers in the Gulf of Mexico Basin Opening project (GUMBO Line 3) in order to provide new constraints on the nature of continental and oceanic crust in the northeastern Gulf of Mexico. GUMBO Line 3 extends~524 km from the continental shelf offshore Pensacola, Florida, across the De Soto Canyon and into the central Gulf basin. Travel times from long offset, wide angle reflections and refractions resolve compressional seismic velocities and layer boundaries for sediment, crystalline crust, and upper mantle. We compare our results with coincident multichannel seismic reflection data. Our velocity model recovers shallow seismic velocities (~2.0-4.5 km/s) that we interpret as evaporites and clastic sediments. A Cretaceous carbonate platform is interpreted beneath the De Soto Canyon with seismic velocities >5.0 km/s. Crystalline continental crust thins seaward along GUMBO Line 3 from 23-10 km across the De Soto Canyon. High seismic velocity lower crust (>7.2 km/s) is interpreted as extensive syn-rift magmatism and possibly mafic underplating, common features at volcanic rift margins with high mantle potential temperatures. In the central Gulf basin we interpret thick oceanic crust (>8 km) emplaced at a slow full-spreading rate (~24 mm/yr). We suggest a sustained thermal anomaly during slow seafloor-spreading conditions led to voluminous basalt flows from a spreading ridge that overprinted seafloor magnetic anomalies in the northeastern Gulf of Mexico.

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Preserved extent of Jurassic flood basalt in the South Georgia Rift: A new interpretation of the J horizon

Cited by 23 publications

References 11 publications

The Jurassic magmatism of the Demerara Plateau (offshore French Guiana) as a remnant of the Sierra Leone hotspot during the Atlantic rifting

The Jurassic magmatism of the Demerara Plateau (offshore French Guiana) as a remnant of the Sierra Leone hotspot during the Atlantic rifting

Seismic velocity structure of the crust and shallow mantle of the Central and Eastern United States by seismic surface wave imaging

Deep crustal structure of the northeastern Gulf of Mexico: Implications for rift evolution and seafloor spreading

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