Three-dimensional passive flow and temperature structure beneath oceanic ridge–ridge–ridge triple junctions

Georgen, J. E.; Lin, Jian

doi:10.1016/s0012-821x(02)00953-6

Cited by 38 publications

(29 citation statements)

References 54 publications

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“…Triple junctions could be the key. Perhaps massive volcanism broke out near triple junctions because when ridges meet at a triple junction, they are a focal point for strong upwelling (Georgen and Lin, 2002). What about the discrepancy between the volcanism along Jurassic to mid-Cretaceous Pacific triple junctions compared to the paucity of such activity during the Late Cretaceous through Cenozoic?…”

Section: Discussionmentioning

confidence: 99%

What built Shatsky Rise, a mantle plume or ridge tectonics?

Sager¹

2005

Plates, Plumes and Paradigms

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Shatsky Rise is an oceanic plateau that formed at the Pacific-Farallon-Izanagi triple junction during the Late Jurassic to Early Cretaceous. Its origin is unclear, but volcanism from a mantle plume or plume head is accepted as an explanation because many observations from the plateau are consistent with the plume head model. Initial eruptions were massive and rapid, with emplacement rates estimated at 1.2-4.6 km 3 /yr, similar to continental flood basalts. The plateau exhibits an age progression, with igneous output waning over time, possibly representing the transition from plume head to plume tail. Shallow water fossils imply that the rise top was subaerial and that thermal and dynamic uplift was significant. Furthermore, the age progression and trends of Shatsky and Hess rises are mimicked by the Mid-Pacific Mountains, to be expected if these features formed by the drift of the plate over mantle plumes. In contrast, several observations do not fit the plume head model. The initial eruption was coincident with a reorientation of the Pacific-Izanagi ridge and an 800-km jump of the triple junction, a low probability occurrence if plume heads behave independently of plate motions. Moreover, this same type of event may have occurred repeatedly, as other western Pacific plateaus occur near the trace of this triple junction (Hess Rise) and the Pacific-Farallon-Phoenix triple junction (Magellan Rise, Manihiki Plateau, MidPacific Mountains). If these other plateaus formed from plumes, either there were many plumes or the plumes defining the triple junction paths exhibited large relative motion. Moreover, rocks recovered from the main Shatsky Rise edifices have midocean ridge basalt (MORB) geochemistry and isotopic signatures, whereas most plume head models imply that lower mantle material, with a different signature, will be carried to the surface. A simpler hypothesis is that Shatsky Rise and other neartriple-junction plateaus were formed as a result of ridge tectonics. One possibility is that decompression melting occurred near the triple junctions during the Mesozoic because the northwest Pacific was located over a region of anomalous asthenosphere that was susceptible to melting given only small perturbations in lithospheric stress. A pitfall for this argument is that changes in the thin, fast-spreading Pacific lithosphere must result in massive volcanism. Although both plume and ridge tectonics hypotheses explain some observations from Shatsky Rise, uncertainties make it premature to conclude which, if either, is correct. Resolution awaits future investigations, which must reveal missing pieces to this puzzle.

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Section: Discussionmentioning

confidence: 99%

What built Shatsky Rise, a mantle plume or ridge tectonics?

Sager¹

2005

Plates, Plumes and Paradigms

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“…It may well be that upwelling -whatever the depth of origin -is entrained into sub-spreading ridge upwelling in the asthenosphere (Fig. 20), which can be strong beneath triple junctions because of the surface divergence (Georgen and Lin, 2002;Georgen 2008;Dordevic and Georgen, 2016). Massif were emplaced in two pulses at least 3 Myr apart.…”

Section: Plume and Plate?mentioning

confidence: 99%

Formation and evolution of Shatsky Rise oceanic plateau: Insights from IODP Expedition 324 and recent geophysical cruises

Sager

Sano

Geldmacher

2016

Earth-Science Reviews

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“…The tectonic scenario of the Azores is not as simple as implied above, due to the complication of the ultra-slow spreading ($2 mm/yr, Vogt and Jung, 2004) Terceria rift (TR). For example, Georgen and Lin (2002) have suggested that this triple junction setting may increase upwelling rates relative to a simple spreading scenario, making 2 cm/yr likely an underestimate.…”

Section: Literaturementioning

confidence: 99%

“…9). We have conservatively assumed a mantle upwelling rate of 2 cm/yr and faster upwelling resulting from a triple junction setting (e.g., Georgen and Lin, 2002) or buoyant upwelling (cf. Bourdon et al, 2005), would reduce the calculated productivity beneath Pico Mountain.…”

Section: Melt Productivity Of Pico Mountain and The Fissure Systemmentioning

confidence: 99%

Determining melt productivity of mantle sources from 238U–230Th and 235U–231Pa disequilibria; an example from Pico Island, Azores

Prytulak

Elliott

2009

Geochimica et Cosmochimica Acta

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Three-dimensional passive flow and temperature structure beneath oceanic ridge–ridge–ridge triple junctions

Cited by 38 publications

References 54 publications

What built Shatsky Rise, a mantle plume or ridge tectonics?

What built Shatsky Rise, a mantle plume or ridge tectonics?

Formation and evolution of Shatsky Rise oceanic plateau: Insights from IODP Expedition 324 and recent geophysical cruises

Determining melt productivity of mantle sources from 238U–230Th and 235U–231Pa disequilibria; an example from Pico Island, Azores

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