The Pacific-Antarctic Ridge–Foundation hotspot interaction: a case study of a ridge approaching a hotspot

Maia, Márcia; Ackermand, D.; Dehghani, G. A.; Gente, Pascal; Hékinian, Roger; Naar, David F.; O’Connor, John; Perrot, K.; Morgan, Jason Phipps; Ramillien, Guillaume; Révillon, Sidonie; Sabetian, A.; Sandwell, David T.; Stoffers, Peter

doi:10.1016/s0025-3227(00)00023-2

Cited by 33 publications

(35 citation statements)

References 44 publications

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“…1b). The age of the plate at the loading time roughly varies from 4.5 Myr in the west to less than 0.5 Myr in the east, in good agreement with the approach rate of 42 mm yr −1 of the PAR to the hotspot (Maia et al 2000). The age of the plate at the loading time roughly varies from 4.5 Myr in the west to less than 0.5 Myr in the east, in good agreement with the approach rate of 42 mm yr −1 of the PAR to the hotspot (Maia et al 2000).…”

Section: G E O L O G I C a L S E T T I N Gsupporting

confidence: 73%

“…Styles of eruption change with changes in the temperature and in the viscosity of the magma, as well as with the height and width of the conduit (Bonatti & Harrison 1988). This reduction, starting around a 2 Myr age of loading (Jordhal et al 1999), is probably due to the capture of part of the plume material by the PAR (Maia et al 2000), limiting the amount of off-axis volcanism. At the Foundation chain, volcano heights do not seem to decrease systematically, instead the change is rather abrupt and takes place around a loading age of ∼2 Myr.…”

Section: T H E E L a S T I C R I G I D I T Y O F T H E O C E A N I C mentioning

confidence: 99%

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The support mechanism of the young Foundation Seamounts inferred from bathymetry and gravity

Maia¹,

Arkani‐Hamed

2002

Geophysical Journal International

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Summary The youngest volcanoes of the Foundation volcanic chain were built on a plate less than 5 Myr near the Pacific–Antarctic ridge (PAR) axis. The progressive approach of the spreading ridge to the hotspot during the last 10 Myr resulted in the building of the edifices upon a progressively younger plate. Estimates of the effective elastic thickness, Te, using two independent methods show that the elastic thickness of the plate diminishes towards the spreading ridge, from 5–3 km to 2–0 km. The spatial variation of Te correlates with a significant change in both the morphology and the volume of the volcanoes, suggesting an important control of the elastic thickness on the volcanic processes. The reduction in Te also explains conveniently the reduction in the distance between the North and the South Systems, the double volcanic line that characterizes the young part of the Foundation chain, in the direction of young loading ages. The South System formed at the top of a flexural bulge created by the emplacement of the North System, the main volcanic line. The low Te estimate for the South System and the shape of the Bouguer anomalies confirm this model. The effective elastic thicknesses obtained in this study are well matched by isotherms between 200°C and 300°C and support the hypothesis of a weak plate. Three mechanisms possibly acted to lower the plate rigidity: Re‐heating of a ‘normal’ plate by the hotspot (North System); local fracturing (South System) and the creation of a thin lithosphere at the PAR axis by the coupling of a hotspot and the ridge‐related melting zones (near‐ridge volcanoes).

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Section: G E O L O G I C a L S E T T I N Gsupporting

confidence: 73%

Section: T H E E L a S T I C R I G I D I T Y O F T H E O C E A N I C mentioning

confidence: 99%

The support mechanism of the young Foundation Seamounts inferred from bathymetry and gravity

Maia¹,

Arkani‐Hamed

2002

Geophysical Journal International

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“…In the same region and in the North Atlantic Ocean, the interaction between OIB materials and the depleted mantle materials (ridge-hotspot interaction) in the oceanic ridges nearby have also been reported. The metasomatism and contamination of the OIB materials resulted in not only the formation of T-MORB and E-MORB, but also the eruption of andesites [30,31] .…”

Section: Tectonic Significance Of Zongwulong Zonementioning

confidence: 99%

Geochemistry and spatial distribution of late-Paleozoic mafic volcanic rocks in the surrounding areas of the Gonghe Basin: Implications for Majixueshan triple-junction and east Paleotethyan archipelagic ocean

Guo

Zhang

Sun

et al. 2007

Sci. China Ser. D-Earth Sci.

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The late-Paleozoic mafic volcanic rocks occurring in the surrounding areas of the Gonghe basin are distributed in the A'nyêmaqên ophiolite zone, Zongwulong tectonic zone and Kuhai-Saishitang volcanic zone. The mafic volcanics in the A'nyêmaqên zone formed an ancient ridge-centered hotspot around the Majixueshan OIB, the Kuhai-Saishitang mafic rocks consist of E-MORB and continental rift basalts and the Zongwulong volcanic rocks are enriched N-MORB. The regionally low Nb/U and Ce/Pb ratios reflect the influence of the OIB material on the mafic magma source. From geochemistry, spatial distribution and tectonic relationship of the mafic rocks, an ancient triple-junction centered at the Majixueshan can be inferred. The existence of the Kuhai-Saishitang aulacogen may have provided a tectonic channel for the Majixueshan OIB materials metasomatizing the magma source for the Zongwulong rocks. The formation of the triple-junction and the rifting of the Zongwulong zone have separated the orogens and massifs in the region.

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“…Even though it has been shown in a previous publication (Haase et al, 2005) that some of the evolved magmas from this ridge segment have suffered contamination by probably altered oceanic crust, the selected samples are uncontaminated basaltic glasses ( Pb and La/Sm ratios occurring at the ridge/seamount intersection (Hekinian et al, 1997;Hekinian et al, 1999;Maia et al, 2000;Haase et al, 2005). These variations have been interpreted as evidence of mixing between incompatible element-enriched mantle plume material from the Foundation plume and MORB source material being relatively depleted in those elements (Maia et al, 2000;Haase et al, 2005). The spreading axis along this segment of the PAR is unusually shallow, rising up to 2100 m compared to a typical ridge depth of 3800 m for the Pacific ridge systems (Lonsdale, 1994).…”

Section: The Sample Setmentioning

confidence: 99%

Plume–ridge interaction revisited: Evidence for melt mixing from He, Ne and Ar isotope and abundance systematics

Stroncik¹,

Niedermann²,

Haase³

2008

Earth and Planetary Science Letters

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Submarine volcanic glass He, Ne and Ar data from the Pacific-Antarctic-Rise at its intersection with the Foundation Seamount Chain have been obtained to further elucidate one of the main outstanding problems in plume-ridge interaction studies: the physical state in which mantle flow and mixing occur in those settings. Mixing of plume mantle and mid-ocean ridge basalt source material may either be in the form of two solids, of solid-melt or of two melt phases only. The positive correlation of 4 He concentrations, combined with a lack of correlation between 4 He/ 40 Ar* and ridge depth or MgO concentration, indicate that the enriched mantle plume material has been extensively degassed prior to mixing with the mid-ocean ridge source material. Degassing of the plume source and mid-ocean ridge source material prior to mixing is also suggested by the He versus Pb isotope systematics. However, the occurrence of degassing processes requires the existence of melts, implying that mixing between the plume and the mid-ocean ridge material occurs in the physical form of melts.Keywords: plume-ridge interaction, noble gases, mixing processes, partial melting, degassing INTRODUCTIONHotspots and mid-ocean ridges (MORs) represent the main features above ascending material of the Earth's mantle where mass and thermal fluxing between the Earth's interior and the surface take place. In areas where hotspots are located close to MORs the mantle plume flow creating the hotspot at the surface interacts with the ridge system as indicated by along-axis bathymetric and gravitational anomalies as well as geochemical and isotopic anomalies of mid-ocean ridge basalts (MORBs) (e.g. Ito et al., 2003). Today 21 of the about 50 active hot spots have been identified to interact with MORs, inducing such anomalies along 15 to 20% of the length of the global MOR system. Plume-ridge interaction processes have been the subject of p. 2 geochemical and geophysical studies because they provide information on mantle flow and melting dynamics. An important question in this context is the physical form of mantle flow and mixing, which may either be as two solids, as solid-melt or as two melt phases only (e.g. Ito et al., 2003). Geophysical models of plume-ridge interaction indicate that solid plume material would simply push the depleted mantle material away as it expands along-axis with little or no mixing occurring, resulting in a sudden change of chemical and isotopic composition at the edge of plume influence instead of the observed gradients (Feighner and Richards, 1995;Ito et al., 1997;Braun and Sohn, 2003;Ito et al., 2003). Similar predictions arise from numerical models simulating the entrainment of ambient mantle material into plumes rising vertically through the mantle (Farnetani and Richards, 1995;Farnetani et al., 2002). Richards and Griffith (1989), on the other hand, have shown experimentally that in fastspreading environments a strong deflection of a plume by horizontal flow of ambient mantle could occur, resulting in significant en...

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The Pacific-Antarctic Ridge–Foundation hotspot interaction: a case study of a ridge approaching a hotspot

Cited by 33 publications

References 44 publications

The support mechanism of the young Foundation Seamounts inferred from bathymetry and gravity

The support mechanism of the young Foundation Seamounts inferred from bathymetry and gravity

Geochemistry and spatial distribution of late-Paleozoic mafic volcanic rocks in the surrounding areas of the Gonghe Basin: Implications for Majixueshan triple-junction and east Paleotethyan archipelagic ocean

Plume–ridge interaction revisited: Evidence for melt mixing from He, Ne and Ar isotope and abundance systematics

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