History of the Pacific Superplume: Implications for Pacific Paleogeography Since the Late Proterozoic

Utsunomiya, Atsushi; Ota, Tsutomu; Windley, Brian F.; Suzuki, Norihito; Uchio, Yuko; Munekata, Kuniko; Maruyama, Shigenori

doi:10.1007/978-1-4020-5750-2_13

Cited by 21 publications

(11 citation statements)

References 166 publications

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“…The sea-level fluctuation of AE300 m in the Phanerozoic could be explained by the glacial and non-glacial periods, and partial mantle overturn when high-temperature and fertile lower mantle materials replaced the upper mantle catastrophically such as during the Cretaceous (120e85 Ma) pulse period (Larson, 1991;Utsunomiya et al, 2007). Another pulse period was mid-Paleozoic when huge batholith belts were formed similar to the Cretaceous pulse.…”

Section: Rapid Decrease Of Sea-level During the Neoproterozoicmentioning

confidence: 96%

The naked planet Earth: Most essential pre-requisite for the origin and evolution of life

Maruyama

Ikoma

Genda

et al. 2013

Geoscience Frontiers

126

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a b s t r a c tOur blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet. Here we speculate the processes that led to the birth of early life on Earth and its aftermath, finally leading to the evolution of metazoans. We evaluate: (1) the source of nutrients, (2) the chemistry of primordial ocean, (3) the initial mass of ocean, and (4) the size of planet. Among the life-building nutrients, phosphorus and potassium play a key role. Only three types of rocks can serve as an adequate source of nutrients: (a) continent-forming TTG (granite), enabling the evolution of primitive life to metazoans; (b) primordial continents carrying anorthosite with KREEP (Potassium, Rare Earth Elements, and Phosphorus) basalts, which is a key to bear life; (c) carbonatite magma, enriched in radiogenic elements such as U and Th, which can cause mutation to speed up evolution and promote the birth of new species in continental rift settings. The second important factor is ocean chemistry. The primordial ocean was extremely acidic (pH ¼ 1e2) and enriched in halogens (Cl, F and others), S, N and metallic elements (Cd, Cu, Zn, and others), inhibiting the birth of life. Plate tectonics cleaned up these elements which interfered with RNA. Blue ocean finally appeared in the Phanerozoic with pH ¼ 7 through extensive interaction with surface continental crust by weathering, erosion and transportation into ocean. The initial ocean mass was also important. The birth of life and aftermath of evolution was possible in the habitable zone with 3e5 km deep ocean which was able to supply sufficient nutrients. Without a huge landmass, nutrients cannot be supplied into the ocean only by ridge-hydrothermal circulation in the Hadean. Finally, the size of the planet plays a crucial role. Cooling of massive planets is less efficient than smaller ones, so that return-flow of seawater into mantle does not occur until central stars finish their main sequence. Due to the suitable size of Earth, the dawn of Phanerozoic witnessed the initiation of return-flow of seawater into the mantle, leading to the emergence of huge landmass above sea-level, and the distribution of nutrients on a global scale. Oxygen pump also played a critical role to keep high-PO 2 in atmosphere since then, leading to the emergence of ozone layer and enabling animals and plants to invade the land.To satisfy the tight conditions to make the Earth habitable, the formation mechanism of primordial Earth is an important factor. At first, a 'dry Earth' must be made through giant impact, followed by magma ocean to float nutrient-enriched primordial continents (anorthosite þ KREEP). Late bombardment from asteroid belt supplied water to make 3e5 km thick ocean, and not from icy meteorites from Geoscience Frontiers 4 (2013) 141e165Kuiper belt beyond cool Jupiter. It was essential to meet the above conditions that enabled the Earth as a habitable planet with evolved life forms. The tight constraints that we evaluate for birth and evolution of l...

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Section: Rapid Decrease Of Sea-level During the Neoproterozoicmentioning

confidence: 96%

The naked planet Earth: Most essential pre-requisite for the origin and evolution of life

Maruyama

Ikoma

Genda

et al. 2013

Geoscience Frontiers

126

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“…They produce oceanic island basalt (OIB) with an enriched mantle signature [e.g., Hart, 1984], which suggests that their origin is deep in the mantle. In the Cretaceous period [e.g., McNutt, 1998;Utsunomiya et al, 2007], this region experienced massive eruptions that produced large oceanic plateaus. These phenomena all suggest the presence of a major hot mantle plume, which leads to the hypothesis of a superplume in the deep mantle beneath the South Pacific [Larson, 1991], though its size, origin depth, and even presence remain controversial.…”

Section: Introductionmentioning

confidence: 99%

South Pacific mantle plumes imaged by seismic observation on islands and seafloor

Suetsugu

Isse

Tanaka

et al. 2009

Geochem Geophys Geosyst

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[1] The South Pacific region is characterized by a broadly elevated seafloor known as the South Pacific superswell. This region has a concentration of midplate volcanoes that experienced massive eruptions in the mid-Cretaceous period (90-120 Ma). These characteristics suggest the presence of a large-scale mantle plume beneath the South Pacific, called the South Pacific superplume. The geometry, origin depth, temperature, and composition of the superplume remain controversial, however, mainly due to the lack of seismological data that documents the mantle structure beneath the South Pacific. Seismic stations are sparse in the area due to its remote ocean environment. To obtain a better seismic image of the superplume, we deployed temporary broadband seismographs on oceanic islands and the seafloor in the South Pacific, which made possible the highest spatial resolution that has ever been achieved for the mantle structure beneath the region. The seismic image obtained from this new seismic data indicates that large-scale lowvelocity anomalies (on the order of 1000 km in diameter), indicative of the superplume, are located from the bottom of the mantle to a depth of 1000 km, and small-scale low-velocity anomalies (on the order of 100 km in diameter) are present above it. A comparison of the seismic image with recent mantle convection studies based upon laboratory and numerical experiments suggests that the superplume may be a hot and chemically distinct mantle dome, and that the small-scale anomalies may be narrow plumes generated from the top of the dome. This model may explain various characteristics of hot spots in the South Pacific, such as the seafloor swell, short-lived hot spot chains, and the periodicity of massive eruptions.

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“…However, the CAOB includes numerous occurrences of accreted Phanerozoic OPS units with OIB and MORB (Safonova 2009;Safonova and Santosh 2014) and there are plenty of Cretaceous, Jurassic, and, in places, older accretionary complexes around the whole Pacific: in Chile, Peru, California, Alaska, Kamchatka, Japan, Philippines, etc. (Maruyama 2002;Utsunomiya et al 2007). We think that preserved fragments of accreted OPS are of key importance for identification of P-type orogens in Asia as places of most active continental growth.…”

Section: P-type Orogens: Intra-oceanic Arcs and Subduction Polaritymentioning

confidence: 95%

Asia: a frontier for a future supercontinent Amasia

Safonova

Maruyama

2014

International Geology Review

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Asia is the world's largest but youngest continent, in which Pacific-type (P-type) and collision-type (C-type) orogenic belts coexist with numerous amalgamated continental blocks. P-type orogens represent major sites of continental growth through tonalite-trondhjemite-granodiorite type (TTG-type) juvenile granitoid magmatism and accretion of oceanic crust and intraoceanic arcs. The Asian continent includes several P-type orogenic belts, of which the largest are the Central Asian and Western Pacific. The Central Asian Orogenic Belt is dominated by P-type fossil orogens arranged with a regular northward subduction polarity. The Western Pacific is characterized by ongoing P-type orogeny related to the westward subduction of the Pacific plate. Asia has a multi-cratonic structure and its post-Palaeozoic history has witnessed amalgamation of the Laurasia composite continent and Pangaea supercontinent. Nowadays, Asia is surrounded by double-sided subduction zones, which generate new TTG-type crust and supply oceanic crust and microcontinents to its active margins. The TTGcrust can be tectonically eroded and subducted down to the mantle transition zone to form a 'second' continent, which may generate mantle upwelling, plumes, and extensive intra-plate volcanism. Moreover, recent plate movements around Asia are dominated by northward directions, which resulted in the India-Eurasia and Arabia-Eurasia collisions beginning at 50-45 and 23-20 Ma, respectively, and will result in Africa-Eurasia collision in the near future. Therefore, Asia is the best candidate to serve as the nucleus for a future supercontinent 'Amasia', likely to form 200-250 Ma in the future. In this paper we unravel a puzzle of continental growth in Asia through P-type orogeny by discussing its tectonic history and geological structure, subduction polarity in P-type orogens, tectonic erosion of TTG-type crust and arc subduction at convergent margins, generation of mantle plumes, and prospects of Asia growth and overgrowth.

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History of the Pacific Superplume: Implications for Pacific Paleogeography Since the Late Proterozoic

Cited by 21 publications

References 166 publications

The naked planet Earth: Most essential pre-requisite for the origin and evolution of life

The naked planet Earth: Most essential pre-requisite for the origin and evolution of life

South Pacific mantle plumes imaged by seismic observation on islands and seafloor

Asia: a frontier for a future supercontinent Amasia

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