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Demerara Rise, offshore Suriname; magma-rich segment of the central Atlantic Ocean, and conjugate to the Bahamas Hot Spot

Kyle R. Reuber, Jim Pindell and Brian W. Horn
Demerara Rise, offshore Suriname; magma-rich segment of the central Atlantic Ocean, and conjugate to the Bahamas Hot Spot
Interpretation (Tulsa) (May 2016) 4 (2): T141-T155

Abstract

The Demerara Rise is a prominent bathymetric feature that has been considered as a broad expression of shallow continental basement and used in conjunction with the Guinea Plateau as a pinning point for circum-Atlantic plate reconstructions. Previously, shallow-penetration, poorly imaged seismic data over the Demerara Rise were modeled with the lower sequences interpreted as continental crust at relatively shallow depths. However, new long-offset, deeply penetrating seismic data provide evidence that basement nearly or entirely comprises excessively thick volcanic strata (approximately 21 km). Seismic character and geometry, 2D gravity modeling, and volcanic margin analogs were used to identify unfaulted, convex-upward seaward dipping reflector (SDR) packages. These steeply dipping (approximately 20 degrees ) igneous successions are westwardly divergent, and occur as offlapping reflector sets in trains as long as 250 km. This rift-related volcanism now recognized at the Demerara Rise was probably conjugate to syn-rift volcanism in South Florida/Great Bahama Bank, and from this we have predicted a volcanic element for the Guinea Plateau. This volcanism could be linked to a Bahamas hot spot at the initial opening of the Central Atlantic. Six SDR packages have been interpreted below the Late Jurassic-Early Cretaceous carbonate section of the rise, indicating that the early volcanism produced a marine substrate upon which the subsequent carbonate bank section developed. We have inferred that this Early Cretaceous volcanic/carbonate margin continued into the Guinea Plateau of West Africa. The pre-Aptian section was inverted and peneplained with a strong angular unconformity prior to the Early Cretaceous opening of the Equatorial Atlantic seaway. The newly identified Central Atlantic volcanic margin of the Demerara Rise holds implications of a volcanic origin for its conjugate margins. We have confirmed a voluminous magma-rich opening of the southeastern Central Atlantic.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 4
Serial Issue: 2
Title: Demerara Rise, offshore Suriname; magma-rich segment of the central Atlantic Ocean, and conjugate to the Bahamas Hot Spot
Affiliation: University of Houston, Deptartment of Earth and Atmospheric Sciences, Houston, TX, United States
Pages: T141-T155
Published: 201605
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 48
Accession Number: 2017-000821
Categories: Solid-earth geophysicsApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. chart, sects., geol. sketch maps
N05°00'00" - N10°00'00", W60°00'00" - W55°00'00"
Secondary Affiliation: Tectonic Analysis, GBR, United KingdomION GeoVentures, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201701
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