Ridge–hotspot interaction: the Pacific–Antarctic Ridge and the foundation seamounts

Ridge–hotspot interaction: the Pacific–Antarctic Ridge and the foundation seamounts The study of different magmatic provinces between the Resolution fracture zone (33°S–131°W) and the Pacific–Antarctic Ridge (PAR) axis (37°S–111°W) suggests that similar processes of interaction between hotspot and spreading axial magmatism occurred 20–25 Ma and 0–5 Ma ago. There is evidence of this process from the changes in composition observed in the lavas erupted near 400–300 km between the present day PAR axis (37°S–111′W) and the eastern tip of the Foundation Seamount (FS) hotspot near 36°20′S–114°W where the last alkali enriched volcanics (K/Ti>0.30, Zr/Y>6 and (Ce/Yb) N >4) have erupted. This transitional province between the PAR and the FS consists of volcanic cones built on several volcanic ridges (<200 km in length) which have erupted less enriched volcanics such as E-(K/Ti=0.25–0.33, Zr/Y=5–6 and (Ce/Yb) N =3–4) and T-(K/Ti=0.11–0.25, Zr/Y=2–4 and (Ce/Yb) N =1–2) MORBs than those from the FS. It is also noticed that there is a general decrease in the degree of the basalt alkalinity (more T-MORBs) towards the PAR axis. The limit of the FS hotspot influence corresponds to the area where the VR intersect the PAR axis for a distance of about 100 km along its strike between 37°10′S and 38°20′S. Indeed, the lava erupted further to the north and to the south of these latitudes contains N-MORBs (K/Ti=0.05–0.11, Zr/Y<3 and (Ce/Yb) N =<2). Many Old Pacific Seamounts (OPS, >20 Ma) also built on volcanic ridges are identified west (>1200 km from the PAR axis) of a Failed Rift Propagator (FRP) forming the eastern boundary of the ancient Selkirk microplate. Some of these seamounts made of alkali basalts were built during the initiation of the FS hotspot 20–23 Ma ago. The interaction and the influence (thermal) of mantle plume magmatism with the ancient spreading ridge of the Farallon–Pacific plates was responsible for the eruptions of the T-MORBs and andesitic lavas. This situation is comparable to that presently observed on the PAR axis where silicic lavas are also erupted in association with T-MORBs. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Marine Geology Elsevier

Ridge–hotspot interaction: the Pacific–Antarctic Ridge and the foundation seamounts

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Publisher
Elsevier
Copyright
Copyright © 1999 Elsevier Science B.V.
ISSN
0025-3227
eISSN
1872-6151
D.O.I.
10.1016/S0025-3227(99)00027-4
Publisher site
See Article on Publisher Site

Abstract

The study of different magmatic provinces between the Resolution fracture zone (33°S–131°W) and the Pacific–Antarctic Ridge (PAR) axis (37°S–111°W) suggests that similar processes of interaction between hotspot and spreading axial magmatism occurred 20–25 Ma and 0–5 Ma ago. There is evidence of this process from the changes in composition observed in the lavas erupted near 400–300 km between the present day PAR axis (37°S–111′W) and the eastern tip of the Foundation Seamount (FS) hotspot near 36°20′S–114°W where the last alkali enriched volcanics (K/Ti>0.30, Zr/Y>6 and (Ce/Yb) N >4) have erupted. This transitional province between the PAR and the FS consists of volcanic cones built on several volcanic ridges (<200 km in length) which have erupted less enriched volcanics such as E-(K/Ti=0.25–0.33, Zr/Y=5–6 and (Ce/Yb) N =3–4) and T-(K/Ti=0.11–0.25, Zr/Y=2–4 and (Ce/Yb) N =1–2) MORBs than those from the FS. It is also noticed that there is a general decrease in the degree of the basalt alkalinity (more T-MORBs) towards the PAR axis. The limit of the FS hotspot influence corresponds to the area where the VR intersect the PAR axis for a distance of about 100 km along its strike between 37°10′S and 38°20′S. Indeed, the lava erupted further to the north and to the south of these latitudes contains N-MORBs (K/Ti=0.05–0.11, Zr/Y<3 and (Ce/Yb) N =<2). Many Old Pacific Seamounts (OPS, >20 Ma) also built on volcanic ridges are identified west (>1200 km from the PAR axis) of a Failed Rift Propagator (FRP) forming the eastern boundary of the ancient Selkirk microplate. Some of these seamounts made of alkali basalts were built during the initiation of the FS hotspot 20–23 Ma ago. The interaction and the influence (thermal) of mantle plume magmatism with the ancient spreading ridge of the Farallon–Pacific plates was responsible for the eruptions of the T-MORBs and andesitic lavas. This situation is comparable to that presently observed on the PAR axis where silicic lavas are also erupted in association with T-MORBs.

Journal

Marine GeologyElsevier

Published: Sep 1, 1999

References

  • Noble gas evidence for a lower mantle component in MORBs from the southern East Pacific Rise: decoupling of helium and neon isotope systematics
    Niedermann, S; Bach, W; Erzinger, J
  • Migration rate of volcanism along the Foundation Chain, SE Pacific
    O'Connor, J; Stoffers, P; Wijbrans, J.R
  • The generation of a compositional lithosphere by mid-ocean ridge melting and its effect on subsequent off-axis hotspot upwelling and melting
    Phipps Morgan, J
  • The dynamics of plume–ridge interaction: 1. Ridge-centered plumes
    Ribe, N.M; Christensen, U.R; Theibing, J
  • New observations on mid-plate volcanism and the tectonic history of the Pacific Plate
    Searle, R.C; Francheteau, J; Corniglia, B

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