LIP Reading: Recognizing Oceanic Plateaux in the Geological Record

Kerr, Andrew C.; White, Rosalind V.; Saunders, Andrew D.

doi:10.1093/petrology/41.7.1041

Cited by 127 publications

(73 citation statements)

References 107 publications

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“…Depending on their origin, submarine ridge basalts can also have MORB or ocean-island basalt OIB signatures. It is quite likely that many greenstones and mafic accreted units, identified as accreted ophiolites or oceanic crust, may actually be oceanic plateaus (see Table 4 in Kerr et al, 2000). For example, the hotspot-related greenstones of the Chugoku and Chichibu belts in Japan were reinterpreted as accreted oceanic plateau/submarine ridges rather than the earlier inference of mid-ocean ridge basalts, based on high Zr / Y ratios that are more similar to OIB geochemical signatures (Tatsumi et al, 2000).…”

Section: Oceanic Plateaus Submarine Ridges and Seamounts: Accreted mentioning

confidence: 96%

“…Kerr et al (2000) suggest that after mafic oceanic plateaus are accreted or collided, causing the subduction zone to jump, silicic magmas intrude and "mature" the accreted plateau lithology towards a more continental crust lithology. The basal cumulate layer may be a ductile layer that serves as a detachment to allow for underplating, an idea originally speculated by Schubert and Sandwell (1989) to develop in plateaus that exceed 15 km in thickness based on the rheological relationship of strength with depth.…”

Section: Oceanic Plateaus Submarine Ridges and Seamounts: Accreted mentioning

confidence: 99%

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Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Tetreault

Buiter

2014

Solid Earth

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Abstract. Allochthonous accreted terranes are exotic geologic units that originated from anomalous crustal regions on a subducting oceanic plate and were transferred to the overriding plate by accretionary processes during subduction. The geographical regions that eventually become accreted allochthonous terranes include island arcs, oceanic plateaus, submarine ridges, seamounts, continental fragments, and microcontinents. These future allochthonous terranes (FATs) contribute to continental crustal growth, subduction dynamics, and crustal recycling in the mantle. We present a review of modern FATs and their accreted counterparts based on available geological, seismic, and gravity studies and discuss their crustal structure, geological origin, and bulk crustal density. Island arcs have an average crustal thickness of 26 km, average bulk crustal density of 2.79 g cm −3 , and three distinct crustal units overlying a crust-mantle transition zone. Oceanic plateaus and submarine ridges have an average crustal thickness of 21 km and average bulk crustal density of 2.84 g cm −3 . Continental fragments presently on the ocean floor have an average crustal thickness of 25 km and bulk crustal density of 2.81 g cm −3 . Accreted allochthonous terranes can be compared to these crustal compilations to better understand which units of crust are accreted or subducted. In general, most accreted terranes are thin crustal units sheared off of FATs and added onto the accretionary prism, with thicknesses on the order of hundreds of meters to a few kilometers. However, many island arcs, oceanic plateaus, and submarine ridges were sheared off in the subduction interface and underplated onto the overlying continent. Other times we find evidence of terrane-continent collision leaving behind accreted terranes 25-40 km thick. We posit that rheologically weak crustal layers or shear zones that were formed when the FATs were produced can be activated as detachments during subduction, allowing parts of the FAT crust to accrete and others to subduct. In many modern FATs on the ocean floor, a sub-crustal layer of high seismic velocities, interpreted as ultramafic material, could serve as a detachment or delaminate during subduction.

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Section: Oceanic Plateaus Submarine Ridges and Seamounts: Accreted mentioning

confidence: 96%

Section: Oceanic Plateaus Submarine Ridges and Seamounts: Accreted mentioning

confidence: 99%

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Tetreault

Buiter

2014

Solid Earth

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“…As a plume rises to the lithosphere, adiabatic decompression results in lower solidus temperatures and causes progressively greater degrees of melting (Condie, 2001). This indicates that the source of the nonenriched type basalts underwent a greater degree of melting than the source of the enriched type that caused its flat HREE pattern on the primitive mantle -normalized plot, with no garnet left behind in the residue (Kerr et al, 2000). This is confirmed by their higher Lu/Hf and lower La/Sm ratios in Figure 10b.…”

Section: Petrogenesis Of the Basaltic Greenstonesmentioning

confidence: 78%

“…Subsequently, alkali basalts that form by smaller degrees of partial melting may cover the shield volcano as cap rock (Condie, 2001;Staudigel and Clague, 2010). This evolution is also applicable to many other oceanic intraplate volcanoes, including oceanic plateaus (Tejada et al, 1996;Kerr et al, 2000;Kerr and Mahoney, 2007;Bryan et al, 2008). Accordingly, in the primitive mantlenormalized incompatible element plots (Figs.…”

Section: Petrogenesis Of the Basaltic Greenstonesmentioning

confidence: 98%

Middle Paleozoic greenstones of the Hangay region, central Mongolia: Remnants of an accreted oceanic plateau and forearc magmatism

Erdenesaihan

Ishiwatari

Orolmaa

et al. 2013

Journal of Mineralogical and Petrological Sciences

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The Hangay -Hentey belt in Central Mongolia constitutes a Pacific -type accretionary orogen that formed through the evolution and closure of the Hangay -Hentey paleo -ocean during the Early Paleozoic to Early Mesozoic. From this belt, new geochemical and petrological results are presented for greenstones from the Erdenetsogt Formation hosted by the Tsetserleg accretionary terrane in the Hangay region, with particular emphasis on newly found picritic and andesitic rocks. These rocks occur mostly in the lower portion of the Erdenetsogt Formation as massive lavas, sills, and dikes closely associated with varicolored bedded ribbon cherts and siltstones. The protoliths of the studied greenstones comprise (1) enriched, plume -derived tholeiitic greenstones including picrites and ferrobasalts with oceanic plateau basalt affinity, (2) non -enriched, plume -derived tholeiitic basalts with E -MORB affinity, and (3) arc -derived high -Mg andesites (HMAs). The plume -derived rocks are characterized by chemical signatures such as slight LREE enrichment similar to that of tholeiitic OIB and the existence of ferropicrite with high FeO* (>14 wt%) and MgO (12 -22 wt%), which is characteristic of large igneous provinces (LIPs), including oceanic plateaus. Their tholeiitic composition and high -Fe and -Ti contents require melting of the source mantle peridotite with addition of some recycled Fe -and Ti -rich basaltic material. The non -enriched basalts may have been generated by a higher degree of melting of the same source mantle. The HMAs are characterized by glassy texture, high MgO content (up to 7 wt%), and significant LREE enrichment with depletion in Nb and resemble sanukite of the Setouchi volcanic belt, SW Japan. We infer that the Hangay tholeiitic greenstones probably represent an accreted upper section of an oceanic plateau that developed in the deep -water region of the Hangay -Hentey paleo -ocean in the Devonian. The Hangay HMAs may have been produced by subduction of young oceanic plate after an oceanward back -stepping of the subduction zone that was a result of the collision during the Carboniferous of the oceanic plateau and the active continental margin of the Central Mongolian Massif.

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“…Most workers proposed a mantle plume model (Ohtani et al 1989;Arndt 2003) where komatiite erupted in either a plume-related intraplate environment (Lahaye et al 1995;Herzberg 1999) or plumederived oceanic plateaus (Condie and Abbott 1999;Kerr et al 2000;Polat and Kerrich 2000;Chavagnac 2004;Jayananda et al 2008). However, Parman et al (2001) and Grove et al (1999) proposed the generation and emplacement of Barberton komatiite magmas in an arc setting whilst De Wit et al (1987) attributed komatiite magma generation and eruption in the divergent setting of an oceanic spreading centre.…”

Section: Tectonic Context Of Magma Generation and Eruptionmentioning

confidence: 99%

Physical volcanology and geochemistry of Palaeoarchaean komatiite lava flows from the western Dharwar craton, southern India: implications for Archaean mantle evolution and crustal growth

Jayananda

Duraiswami

Aadhiseshan

et al. 2016

International Geology Review

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Palaeoarchaean (3.38-3.35 Ga) komatiites from the Jayachamaraja Pura (J.C. Pura) and Banasandra greenstone belts of the western Dharwar craton, southern India were erupted as submarine lava flows. These high-temperature (1450-1550°C), low-viscosity lavas produced thick, massive, polygonal jointed sheet flows with sporadic flow top breccias. Thick olivine cumulate zones within differentiated komatiites suggest channel/conduit facies. Compound, undifferentiated flow fields developed marginal-lobate thin flows with several spinifex-textured lobes. Individual lobes experienced two distinct vesiculation episodes and grew by inflation. Occasionally komatiite flows form pillows and quench fragmented hyaloclastites. J.C. Pura komatiite lavas represent massive coherent facies with minor channel facies, whilst the Bansandra komatiites correspond to compound flow fields interspersed with pillow facies. The komatiites are metamorphosed to greenschist facies and consist of serpentine-talc ± carbonate, actinolite-tremolite with remnants of primary olivine, chromite, and pyroxene. The majority of the studied samples are komatiites (22.46-42.41 wt.% MgO) whilst a few are komatiitic basalts (12.94-16.18 wt.% MgO) extending into basaltic (7.71 -10.80 wt.% MgO) composition. The studied komatiites are Al-depleted Barberton type whilst komatiite basalts belong to the Al-undepleted Munro type. Trace element data suggest variable fractionation of garnet, olivine, pyroxene, and chromite. Incompatible element ratios (Nb/Th, Nb/U, Zr/Y Nb/Y) show that the komatiites were derived from heterogeneous sources ranging from depleted to primitive mantle. CaO/Al 2 O 3 and (Gd/Yb) N ratios show that the Al-depleted komatiite magmas were generated at great depth (350-400 km) by 40-50% partial melting of deep mantle with or without garnet (majorite?) in residue whilst komatiite basalts and basalts were generated at shallow depth in an ascending plume. The widespread Palaeoarchaean deep depleted mantle-derived komatiite volcanism and sub-contemporaneous TTG accretion implies a major earlier episode of mantle differentiation and crustal growth during ca. 3.6-3.8 Ga.ARTICLE HISTORY

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LIP Reading: Recognizing Oceanic Plateaux in the Geological Record

Cited by 127 publications

References 107 publications

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Middle Paleozoic greenstones of the Hangay region, central Mongolia: Remnants of an accreted oceanic plateau and forearc magmatism

Physical volcanology and geochemistry of Palaeoarchaean komatiite lava flows from the western Dharwar craton, southern India: implications for Archaean mantle evolution and crustal growth

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