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

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doi: 10.1016/j.epsl.2015.05.021
Author(s): O'Connor, John M.; Jokat, Wilfried
Author Affiliation(s): Primary:
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, Vol.424, p.179-190. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. Includes appendices. 69 refs.; illus., incl. 1 table, sketch maps
Summary: The Tristan-Gough hotspot trail on the African plate consists of the Walvis Ridge and a younger province of seamounts and islands. In order to determine the relative motion between the African plate and the Tristan-Gough hotspot it is essential to resolve changes in the age and morphology of the Walvis Ridge. A significant problem is, however, to establish how the vigor and flow of hotspot material to the mid-ocean ridge constructed the Walvis Ridge. We have addressed this issue by measuring an 40Ar/39Ar stratigraphy at three sites across the central Walvis Ridge sampled by Ocean Drilling (DSDP Leg 74). The age-distance relation of volcanism, together with geophysical, geochemical and paleodepth information, suggests collectively that hotspot volcanism was occurring locally c. 72 Ma on an elevated segment of the mid-ocean ridge located close to the Tristan-Gough hotspot. As the mid-ocean ridge migrated away from the hotspot (c. 36 km/Ma) between c. 72 Ma and 68 Ma, hotspot material continued flowing to the mid-ocean ridge and the Walvis Ridge shoaled rapidly (c. 500 m/Ma) to the west, on seafloor that might have been subsiding at a rate consistent with normal crustal cooling. This apparent correlation points to the possibility of an inverse relation between the volume flux of hotspot volcanism and the distance between the mid-ocean ridge and the Tristan-Gough hotspot. We infer that since c. 93 Ma the geometry and motion of the mid-ocean ridge determined where the hotspot material that built the Walvis Ridge was channeled to the plate surface. Furthermore, interplay between hotspot flow, and the changing geometry of the mid-ocean ridge as it migrated relative to the Tristan-Gough hotspot, might explain the age and morphology of the Walvis Ridge. Our finding provides further evidence that the distribution of hotspot volcanism in the southeast Atlantic expresses interaction between deep mantle (plume) and shallow plate tectonic and asthenosphere processes. Abstract Copyright (2015) Elsevier, B.V.
Year of Publication: 2015
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 05 Petrology, Igneous and Metamorphic; 18 Geophysics, Solid-Earth; Absolute age; Ar/Ar; Atlantic Ocean; Atlantic Ocean Islands; Cenozoic; Cretaceous; DSDP Site 516; DSDP Site 525; DSDP Site 527; DSDP Site 528; Dates; Deep Sea Drilling Project; Geophysical profiles; Geophysical surveys; Hot spots; IPOD; Leg 72; Leg 74; Lower Paleocene; Magnetic anomalies; Mantle; Mantle plumes; Mesozoic; Mid-ocean ridges; Ocean floors; Paleocene; Paleogene; Plate boundaries; Plate tectonics; Rio Grande Rise; Seismic profiles; South Atlantic; Structural controls; Surveys; Temporal distribution; Tertiary; Tristan da Cunha; Upper Cretaceous; Volcanism; Walvis Ridge
Coordinates: S290415 S290414 E0025908 E0025907
S283130 S283129 E0021927 E0021926
S280230 S280229 E0014549 E0014547
S301636 S301635 W0351706 W0351707
Record ID: 2015088654
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands