Melting and dissolution of subducting crust at high pressures: the key role of white mica

Schmidt, Max W.; Vielzeuf, Daniel; Auzanneau, Estelle

doi:10.1016/j.epsl.2004.09.020

Cited by 401 publications

(274 citation statements)

References 39 publications

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“…Sr is not carried into the mantle by low-density fluids at T < 900 °C, but is efficiently transported in the higher-T, low-density fluids, melts and high-density fluids, with a partition coefficient of about 20. Schmidt et al (2004) demonstrated that subducted MORB basalts, pelites and greywackes will all develop similar eclogitic mineral assemblages and that the coexisting fluids will be rich in Si and K. Schmidt et al (2004) and Ishikawa et al (2005) both determined that supercritical, solute-rich fluids/melts evolved from the slab would be aqueous and strikingly enriched in B, Ba, Rb and K. It therefore seems likely that the Kessel et al (2005) partitioning relationships will be valid for a wide range of subducted rocks.…”

Section: Origin Of the Crustal Component In The Mafic To Intermediatementioning

confidence: 99%

Sources of post-orogenic calcalkaline magmas: The Arrochar and Garabal Hill–Glen Fyne complexes, Scotland

Clemens

Darbyshire

Flinders

2009

Lithos

109

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The 425 Ma Arrochar and Garabal Hill-Glen Fyne complexes of highland Scotland are examples of post-orogenic magmatism accompanying extensional collapse of an orogen, in this case the Caledonian. The rocks are dominantly high-K series, but range from medium-K to shoshonitic. Mantle upwelling, melting and the intrusion of large volumes of mafic magma into the crust are inferred to have accompanied lithospheric thinning, and to have provided the heat source for melting of young arc crust accreted during the preceding subduction epoch.Fluids evolved from the subducting slab are inferred to have caused high degrees of enrichment in the overlying mantle wedge. Deep in the crust, the mantle-derived, K-rich mafic to intermediate magmas mixed with felsic crustal melts to form the spectrum of magmas intruded in the two complexes. Microgranular enclaves in the granitic rocks represent mafic magmas derived from the enriched mantle and hybridised by reaction, diffusion and mechanical mixing with their host felsic magmas, but they do not form part of the evolutionary series that produced the host magmas. Rather than inheriting its LILEenriched character directly from crustal melts, or from crustal assimilation by mafic magmas, the high-K series may commonly owe at least part of its potassic character to the involvement of mantle (highly metasomatised by slab-derived fluids) as a major magma source. Enclave suites, though prominent in some granitic rocks should not be assumed to represent magmas that played a significant role in the production of the chemical variations in their host magmas.

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Section: Origin Of the Crustal Component In The Mafic To Intermediatementioning

confidence: 99%

Sources of post-orogenic calcalkaline magmas: The Arrochar and Garabal Hill–Glen Fyne complexes, Scotland

Clemens

Darbyshire

Flinders

2009

Lithos

109

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“…The Hohxil dacites exhibit slightly higher Mg # (50-54) than those (b0.47) of metabasaltic and eclogite or metasedimentary rock experimental melts (1-4.0 GPa) (Fig. 6a-d) (e.g., Rapp et al, 1999;Schmidt et al, 2004), indicating that the dacite magmas were slightly hybridized by mantle peridotite during ascent. However, the Hohxil high-Mg andesites have distinctly higher Mg # (64-72) and compatible element (e.g., Ni) contents (Fig.…”

Section: Petrogenesismentioning

confidence: 99%

“…Adakitic magmas can generally be produced by melting of mafic materials, leaving residual phases that include garnet ± rutile but little or no plagioclase (Rapp et al, 1999(Rapp et al, , 2003Xiong et al, 2005). Pelitic sediments and greywackes have the same eclogitic mineralogy (but different mineral proportions) as basaltic rocks at depths N70-100 km (i.e., 2.0~3.5 GPa; Schmidt et al, 2004). Experimental data suggest that sediment-derived melts in equilibrium with garnet are markedly depleted in HREE and enriched in LREE (Johnson and Plank, 1999).…”

Section: Petrogenesismentioning

confidence: 99%

Late Triassic high-Mg andesite/dacite suites from northern Hohxil, North Tibet: Geochronology, geochemical characteristics, petrogenetic processes and tectonic implications

Wang

Chung

et al. 2011

Lithos

102

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“…Recent studies from experimental petrology [1][2][3], geochemical analyses [4][5][6] and geochronological data [7][8][9] have indicated that deeply subducted continental crust experienced partial melting during exhumation. Such anatexis can change mechanical and chemical behaviours of ultrahigh-pressure (UHP) metamorphic rocks.…”

mentioning

confidence: 99%

Dehydration melting of UHP eclogite and paragneiss in the Dabie orogen: Evidence from laboratory experiment to natural observation

Liu

2013

Chin. Sci. Bull.

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Dehydration melting of subducted continental crust is significant during exhumation, and its study from both experimental and petrological observations is of great importance to our understanding of continental geodynamics. Dehydration melting experiments were carried out on ultrahigh-pressure (UHP) eclogite from Bixiling in the Dabie orogen using a piston cylinder at 1.5-3.0 GPa and 800-950°C to investigate partial melting of eclogite induced by phengite breakdown. The phengite-bearing eclogite started to melt at T800-850°C and P=1.5-2.0 GPa and produced about 3% granitic melt. The products of dehydration melting vary with temperature and pressure. Such results provide valuable constraints on the micro-texture related to partial melting of UHP rocks in the Dabie-Sulu orogenic belt. Three types of polyphase inclusions were identified in garnet from the Shuanghe UHP eclogite. K-feldspar and quartz inclusions are interpreted to represent the products of segregation and crystallization of minor amounts of melt that formed during dehydration melting of phengite by the inferred reaction Phengite+Omphacite±Quartz→ Amphibole±Garnet+Melt (K-feldspar+Quartz±Plagioclase). Polyphase inclusions of phengite and K-feldspar+Quartz inclusions were also found in zoisite/clinozoisite and garnet from the Shuanghe garnet-bearing paragneiss. These polyphase inclusions provide evidence for a continuous process from sub-solidus dehydration to partial melting within the UHP gneissic rocks. The compositional variation of garnets demonstrates that breakdown of epidote-group minerals may have played a crucial role during dehydration melting reaction of phengite. The Ti-in-zircon thermometry and Si content of phengite in zircon suggest that partial melting would occur at 783-839°C and 2.0-2.5 GPa. Therefore, both experimental results and petrological observations indicate that dehydration melting and fluid activity within the Dabie UHP rocks at micro-scale are controlled by the breakdown of phengite. dehydration melting, phengite, experimental petrology, polyphase inclusions, ultrahigh-pressure metamorphism, Dabie orogen Citation:Liu Q, Wu Y. Dehydration melting of UHP eclogite and paragneiss in the Dabie orogen: Evidence from laboratory experiment to natural observation. Chin Sci Bull, 2013Bull, , 58: 43904396, doi: 10.1007 Recent studies from experimental petrology [1-3], geochemical analyses [4][5][6] and geochronological data [7][8][9] have indicated that deeply subducted continental crust experienced partial melting during exhumation. Such anatexis can change mechanical and chemical behaviours of ultrahigh-pressure (UHP) metamorphic rocks. It has significant effects on facilitating the deformation mechanisms (or strain localization) of UHP rocks [10,11], increasing the buoyancy of melted rocks and promoting the segregation of partial melts. Thus, partial melting of subducted continental crust is of great significance for understanding the melting event and fluid activity at great depths as well as the rheological property of UHP ro...

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Melting and dissolution of subducting crust at high pressures: the key role of white mica

Cited by 401 publications

References 39 publications

Sources of post-orogenic calcalkaline magmas: The Arrochar and Garabal Hill–Glen Fyne complexes, Scotland

Sources of post-orogenic calcalkaline magmas: The Arrochar and Garabal Hill–Glen Fyne complexes, Scotland

Late Triassic high-Mg andesite/dacite suites from northern Hohxil, North Tibet: Geochronology, geochemical characteristics, petrogenetic processes and tectonic implications

Dehydration melting of UHP eclogite and paragneiss in the Dabie orogen: Evidence from laboratory experiment to natural observation

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