Rocks from the Mantle Transition Zone: Majorite-Bearing Xenoliths from Malaita, Southwest Pacific

Collerson, K. D.; Hapugoda, Sarath; Kamber, Balz S.; Williams, Quentin

doi:10.1126/science.288.5469.1215

Cited by 88 publications

(61 citation statements)

References 55 publications

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“…Similar plume head structures have been identi¢ed in place beneath £ood basalt provinces in South America and India, although the OJP, emplaced into an oceanic plate, is unique in that it did not intrude into deep continental roots that explain the far-traveled nature of the Paranä and Deccan remnant structures. The similar seismically slow thick anomalies of all three hotspot plume heads imply that chemical di¡erentiation at the core^mantle boundary, presumably the source of these mantle plumes, is strong and results in long-lived compositional anomalies [48]. Resultant buoyancy of these structures may indicate that plume head remnants ultimately accrete to continental masses and represent a signi¢cant component of continental growth, increasing the overall volume of tectosphere [49].…”

Section: Discussionmentioning

confidence: 90%

Evidence for a rheologically strong chemical mantle root beneath the Ontong–Java Plateau

Klosko

Russo

Okal

et al. 2001

Earth and Planetary Science Letters

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Shear wave splitting measurements, in conjunction with studies of shear wave velocity structure, indicate that the Ontong^Java Plateau (OJP) large igneous province (LIP) has a thick, compositionally distinct root that diverts asthenospheric mantle flow beneath the Pacific plate. The OJP, the largest of Earth's LIPs, stands 2 km above adjacent Pacific abyssal plains and is composed of mantle plume derived volcanics erupted at 122 and 90 Ma. Surface wave tomography of the Plateau reveals a seismically slow upper mantle root that extends approximately to 300 km depth. The thickness and juxtaposition of the Plateau and the mantle root imply that the OJP is the preserved`head' of a rising mantle plume formed in situ when the LIP erupted. Thus, it is a far-traveled body currently moving northwestwards with the Pacific plate. Shear wave splitting at four seismic stations along the northern margin of the OJP varies systematically: the fast axis of seismic anisotropy at three stations on the NE OJP margin trend NW, parallel to hotspot-defined Pacific absolute plate motion; at a fourth station, on the NW margin of the Plateau, the fast shear wave trend is NE. Upper mantle flow directions delineated by the shear wave splitting could thus represent mantle flow diverted around the leading, northwestern face of the rheologically strong, chemically distinct OJP root. In sum, the Plateau and its deep root appear to be similar to continental tectosphere, except for contrasting seismic velocities. ß

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Section: Discussionmentioning

confidence: 90%

Evidence for a rheologically strong chemical mantle root beneath the Ontong–Java Plateau

Klosko

Russo

Okal

et al. 2001

Earth and Planetary Science Letters

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“…Из предыдущего раздела видно, что некоторые включения в алмазах и некоторые мантийные ксе-нолиты содержат в себе минералы переходной зо-ны мантии [Collerson et al, 2000;Hayman et al, 2005;Brenker et al, 2007;Wirth et al, 2007] (рис. 6).…”

Section: переходная зона и глубокие горизонты верхней мантииunclassified

“…Несмотря на то, что обнаружение мажорита в ксе-нолитах из альноитов о-ва Малайта [Collerson et al, 2000] было поставлено под сомнение [Neal et al, 2001], в других случаях идентификация минералов переходной зоны не подвергалась критике. Таким образом, вещество переходной зоны может участ-вовать в вулканических процессах, по крайней мере при формировании щелочных магм.…”

Section: переходная зона и глубокие горизонты верхней мантииunclassified

“…6)), были обнаружены в мантийных ксенолитах из альноитов острова Малайта в Тихом океане (альноитами называют кимберлитоподобные маг-мы, извергавшиеся в пределах океанической коры). Эти альноиты извергались ~34 млн лет назад в рай-оне плато Онтонг-Ява [Collerson et al, 2000]. Данная работа, однако, была подвергнута критике на том основании, что идентификация минералов осуще-ствлялась по их химическому составу и ИК-спектро-скопии [Neal et al, 2001].…”

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Deep-level geodynamics: boundaries of the process according to geochemic and petrologic data

Иванов¹

2010

Geodyn. Tectonophys.

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Geochemical features for volcanic rocks and petrologic data for deep-seated inclusions, which can be used to infer mass transfer between different geospheres, are reviewed. It is typically believed that slabs can subduct as deep as the core-mantle boundary with the following recycling by plumes coming up to the sublithospheric regions of magma generation. However, the petrologic evidence of the deepest accessible material is limited by the depth of the uppermost lower mantle (~650-700km), i.e. by the depth of the deepest earthquakes. Ferropericlase inclusions in some diamonds do not exclude involvement of deeper mantle horizons, yet do not unambiguously support it. No unambiguous confirmation of involvement of the lower mantle into magma generation underneath volcanically active regions is obtained from geochemical data either, while the geochemical data suggest complete chemical isolation of the Earth's core from the upper mantle processes.Keywords: mantle, subduction, recycling, deep-level geodynamics. Recommended by E.V. Sklyarov 18 October 2009Ivanov A.V. Deep-level geodynamics: boundaries of the process according to geochemic and petrologic data // Geodynamics & Tectonophysics. 2010. V. 1. № 1. P. 87-102. ГЛУБИННАЯ ГЕОДИНАМИКА: ГРАНИЦЫ ПРОЦЕССА ПО ГЕОХИМИЧЕСКИМ И ПЕТРОЛОГИЧЕСКИМ ДАННЫМ А. В. Иванов Институт земной коры СО РАН, 664033, Иркутск, ул. Лермонтова, 128, РоссияАннотация: Проведен анализ геохимических характеристик вулканических пород и петрологических данных по глубинным включениям, которые могут быть использованы для оценки обмена веществом между различными геосферами Земли. Несмотря на то, что обычно рассматривается возможность субдуцирования слэбов вплоть до границы ядро-мантия и последующего возвращения материала в область подлитосферной магмогенерации в форме мантийных плюмов, петрологические доказательства самого глубокого поступления вещества на по-верхность ограничиваются верхними горизонтами нижней мантии (~650-700 км), т.е. глубиной самых глубоких землетрясений. Включения ферропериклаза в некоторых алмазах не опровергают вовлечение и более глубоких горизонтов мантии, однако не дают этому однозначного подтверждения. Геохимические данные также не дают однозначного подтверждения вовлечения вещества нижней мантии в процессы магмогенерации под вулканиче-ски активными районами. В то же время они свидетельствуют о полной вещественной изоляции ядра от верх-немантийных процессов.Ключевые слова: мантия, субдукция, рециклинг, глубинная геодинамика.

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“…However, the relationship between the diverse nature of the Malaitan xenoliths and the unusual generation of the OJP was not examined extensively and remained ambiguous before our studies (Ishikawa et al, 2004) . During our visit to the Solomon Islands in 2000-2001, Collerson et al (2000) reported occurrences of diamond and ultrahigh pressure minerals, such as majorite and silicate perovskite in Malaita alnöites, but no actual mineralogical data. A criticism of the article was published by Neal et al (2001) , which is consistent with my own observations.…”

Section: Historical Background Of Malaitan Xenolithsmentioning

confidence: 99%

Spectacular Mantle Xenoliths Derived from "Oceanic Kimberlite", Malaita, Solomon Islands: A Unique Window into the Earth's Deep Interior

Ishikawa¹

2011

J. Geogr.

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The mantle beneath the world' s largest igneous province, the Cretaceous Ontong Java Plateau in the western Pacific, is accessible via xenoliths from late-stage "kimberlite-like" ultramafic magmas (alnöite) on the Solomon Island of Malaita. The xenoliths can be used to reconstruct the lithospheric stratigraphy (vertical distribution of rock types) beneath the plateau based on geothermobarometry.The results show that the lithosphere forms a genetically unrelated two-layered structure, comprising shallower pre-existing oceanic lithosphere and deeper impinged material regarded as the residual mantle of the Ontong Java Plateau magmatism. This suggests that particular types of Malaitan xenolith represent fragments of mantle plume that possibly originated from the core-mantle boundary.

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Rocks from the Mantle Transition Zone: Majorite-Bearing Xenoliths from Malaita, Southwest Pacific

Cited by 88 publications

References 55 publications

Evidence for a rheologically strong chemical mantle root beneath the Ontong–Java Plateau

Evidence for a rheologically strong chemical mantle root beneath the Ontong–Java Plateau

Deep-level geodynamics: boundaries of the process according to geochemic and petrologic data

Spectacular Mantle Xenoliths Derived from "Oceanic Kimberlite", Malaita, Solomon Islands: A Unique Window into the Earth's Deep Interior

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