The relationship between adakitic, calc-alkaline volcanic rocks and TTGs: implications for the tectonic setting of the Karelian greenstone belts, Baltic Shield

Самсонов, А. В.; Bogina, M. M.; Bibikova, Elena; Petrova, A. Yu.; Shchipansky, A. A.

doi:10.1016/j.lithos.2004.04.051

Cited by 75 publications

(22 citation statements)

References 24 publications

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“…For some subduction zones, it has been reported that magmatism changes from an adakite type to a normal subduction-zone type with increasing depth of the Wadati-Benioff zone (51,54). This change in the major-element chemistry of volcanic rocks is considered further proof that the slab melting is limited to the fore-arc side, whereas SCF as a result of slab dehydration causes normal-type magmatism in most of the subduction zone.…”

Section: Depths Of the Second Critical Endpoints And Their Bearing Onmentioning

confidence: 93%

Slab melting versus slab dehydration in subduction-zone magmatism

Mibe

Kawamoto

Matsukage

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

156

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The second critical endpoint in the basalt-H 2 O system was directly determined by a high-pressure and high-temperature X-ray radiography technique. We found that the second critical endpoint occurs at around 3.4 GPa and 770°C (corresponding to a depth of approximately 100 km in a subducting slab), which is much shallower than the previously estimated conditions. Our results indicate that the melting temperature of the subducting oceanic crust can no longer be defined beyond this critical condition and that the fluid released from subducting oceanic crust at depths greater than 100 km under volcanic arcs is supercritical fluid rather than aqueous fluid and/or hydrous melts. The position of the second critical endpoint explains why there is a limitation to the slab depth at which adakitic magmas are produced, as well as the origin of across-arc geochemical variations of trace elements in volcanic rocks in subduction zones.water | island arc | silicate melt | synchrotron X-ray | high-pressure research W ater plays an important role in subduction-zone magmatism because it can reduce the melting temperature of rocks in subduction zones and hence can generate magmas (1-7). There is a long-standing debate about whether the fluids released from a subducting slab are aqueous fluid, hydrous silicate melt, supercritical fluid (SCF), or a combination of these (2,4,(8)(9)(10)(11)(12). Whether the subducting slab melts or dehydrates depends on the thermal structure and the phase relation of slab materials under hydrous conditions. Therefore, this long-standing question cannot be answered until the detailed stability fields of these fluids are clarified.Under high-pressure (P) and high-temperature (T) conditions, it has been shown that the solubility of both water in silicate melt (13-16) and silicate in aqueous fluid (13, 17-25) increases with increasing P. As a result, silicate melt and aqueous fluid in the interior of the Earth are expected to become SCF, and the hydrous solidus of the system can no longer be defined beyond a certain critical condition (26-36). This condition is called the second (or upper) critical endpoint (26) and is the point of intersection between the critical curve and hydrous solidus. Basalt is one of the dominant constituents of a subducting slab and is considered the main carrier of water that triggers the melting of rocks in subduction zones. Therefore, the second critical endpoint in the basalt-H 2 O system has to be determined in order to understand fully the subduction-zone magmatism.In some silicic silicate-H 2 O systems, the location of the second critical endpoint has been reported [e.g., 1.0 GPa, 1,080°C in the SiO 2 -H 2 O system (13); 1.5 GPa, 670°C in the system NaAlSi 3 O 8 -H 2 O (21); 1.5 GPa, 800°C in the system KAlSi 3 O 8 -H 2 O (36)]. In mafic systems, however, the determination of the second critical endpoints is not easy because of the difficulty in identifying phases (aqueous fluid versus hydrous silicate melt) in the recovered samples quenched from high-P and high-T conditio...

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Section: Depths Of the Second Critical Endpoints And Their Bearing Onmentioning

confidence: 93%

Slab melting versus slab dehydration in subduction-zone magmatism

Mibe

Kawamoto

Matsukage

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

156

View full text Add to dashboard Cite

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“…Research undertaken on other Archean greenstone belts has highlighted the presence of rock associations generally considered to be derived from partial melting of mantle wedge material beneath arcs, including coeval high-Mg andesites (HMA) with sanukitoids (i.e., LSA-type groups) or island-arc andesites, with HSA groups in the same area, suggesting the onset of subduction at the time of formation (e.g., Polat and Kerrich, 2001;Percival et al, 2003;Wang et al, 2004;Samsonov et al, 2005;Naqvi et al, 2006Naqvi et al, , 2009Manya et al, 2007;Manikyamba et al, 2009). The presence of contemporaneous LSA and HSA groups in this study area, particularly in the case of the high-Mg diorites reported by Wang et al (2009) and the granodiorites from the Taishan area, similarly implies a subduction-related origin rather than derivation from the lower crust.…”

Section: Slab Meltingmentioning

confidence: 99%

Geochronology and geochemistry of late Archean adakitic plutons from the Taishan granite–greenstone Terrain: Implications for tectonic evolution of the eastern North China Craton

Peng

2012

Precambrian Research

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“…For the NCC, rapid crustal growth at~2.7 Ga has been well established for the entire craton (e.g., Wu et al, 2005b;Wan et al, 2011). However, distinct from other cratons, such as the Superior (Percival et al, 2001), the western Canada Shield (Sandeman et al, 2006), Wyoming (Rino et al, 2004), the Baltic Shield Halla, 2005;Samsonov et al, 2005), southern West Greenland (Thrane, 2002;Steenfelt et al, 2005), the Pilbara and Yilgarn cratons of Western Australia (Bateman et al, 2001;Blake, 2001;Rasmussen et al, 2005), southern Africa (Poujol et al, 2003) and Zimbabwe (Matthew et al, 1999;Hofmann et al, 2004), about 80% of the exposed igneous rocks in the NCC are~2.5 Ga TTGs and associated rocks (Zhao et al, 2001(Zhao et al, , 2002Wilde et al, 2005). Moreover, the imprint of a major 2.5 Ga tectono-thermal event was particularly strong in the NCC Wan et al, 2012c, and references therein).…”

Section: Continental Crustal Growth and Crustal Evolutionmentioning

confidence: 99%