The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform

Olivier Reubi - One of the best experts on this subject based on the ideXlab platform.

  • a dearth of intermediate melts at subduction zone volcanoes and the Petrogenesis of arc andesites
    Nature, 2009
    Co-Authors: Olivier Reubi, Jonathan D. Blundy
    Abstract:

    Olivier Reubi and Jon Blundy present an alternative view of andesite Petrogenesis and argue that true liquids of intermediate composition (59 to 66 wt% SiO2) are far less common in the subvolcanic reservoirs of arc volcanoes than is suggested by the abundance of erupted magma within this compositional range. This alternative view resolves several puzzling aspects of arc volcanism and provides important clues to the integration of plutonic and volcanic records. A large proportion of the magmas erupted at continental arc volcanoes are andesites, which are regarded as a major component in the formation of continental crust — consequently, it is important to understand andesite Petrogenesis. Here, an alternative view of andesite Petrogenesis is presented, based on a review of quenched glassy melt inclusions trapped in phenocrysts, whole-rock chemistry, and high-pressure and high-temperature experiments; this new view resolves several puzzling aspects of arc volcanism. Andesites represent a large proportion of the magmas erupted at continental arc volcanoes and are regarded as a major component in the formation of continental crust1. Andesite Petrogenesis is therefore fundamental in terms of both volcanic hazard and differentiation of the Earth. Andesites typically contain a significant proportion of crystals showing disequilibrium petrographic characteristics indicative of mixing or mingling between silicic and mafic magmas, which fuels a long-standing debate regarding the significance of these processes in andesite Petrogenesis2 and ultimately questions the abundance of true liquids with andesitic composition. Central to this debate is the distinction between liquids (or melts) and magmas, mixtures of liquids with crystals, which may or may not be co-genetic. With this distinction comes the realization that bulk-rock chemical analyses of petrologically complex andesites can lead to a blurred picture of the fundamental processes behind arc magmatism. Here we present an alternative view of andesite Petrogenesis, based on a review of quenched glassy melt inclusions trapped in phenocrysts, whole-rock chemistry, and high-pressure and high-temperature experiments. We argue that true liquids of intermediate composition (59 to 66 wt% SiO2) are far less common in the sub-volcanic reservoirs of arc volcanoes than is suggested by the abundance of erupted magma within this compositional range. Effective mingling within upper crustal magmatic reservoirs obscures a compositional bimodality of melts ascending from the lower crust, and masks the fundamental role of silicic melts (≥66 wt% SiO2) beneath intermediate arc volcanoes. This alternative view resolves several puzzling aspects of arc volcanism and provides important clues to the integration of plutonic and volcanic records.

  • a dearth of intermediate melts at subduction zone volcanoes and the Petrogenesis of arc andesites
    Nature, 2009
    Co-Authors: Olivier Reubi, Jonathan D. Blundy
    Abstract:

    Andesites represent a large proportion of the magmas erupted at continental arc volcanoes and are regarded as a major component in the formation of continental crust. Andesite Petrogenesis is therefore fundamental in terms of both volcanic hazard and differentiation of the Earth. Andesites typically contain a significant proportion of crystals showing disequilibrium petrographic characteristics indicative of mixing or mingling between silicic and mafic magmas, which fuels a long-standing debate regarding the significance of these processes in andesite Petrogenesis and ultimately questions the abundance of true liquids with andesitic composition. Central to this debate is the distinction between liquids (or melts) and magmas, mixtures of liquids with crystals, which may or may not be co-genetic. With this distinction comes the realization that bulk-rock chemical analyses of petrologically complex andesites can lead to a blurred picture of the fundamental processes behind arc magmatism. Here we present an alternative view of andesite Petrogenesis, based on a review of quenched glassy melt inclusions trapped in phenocrysts, whole-rock chemistry, and high-pressure and high-temperature experiments. We argue that true liquids of intermediate composition (59 to 66 wt% SiO(2)) are far less common in the sub-volcanic reservoirs of arc volcanoes than is suggested by the abundance of erupted magma within this compositional range. Effective mingling within upper crustal magmatic reservoirs obscures a compositional bimodality of melts ascending from the lower crust, and masks the fundamental role of silicic melts (>/=66 wt% SiO(2)) beneath intermediate arc volcanoes. This alternative view resolves several puzzling aspects of arc volcanism and provides important clues to the integration of plutonic and volcanic records.

Jonathan D. Blundy - One of the best experts on this subject based on the ideXlab platform.

  • a dearth of intermediate melts at subduction zone volcanoes and the Petrogenesis of arc andesites
    Nature, 2009
    Co-Authors: Olivier Reubi, Jonathan D. Blundy
    Abstract:

    Olivier Reubi and Jon Blundy present an alternative view of andesite Petrogenesis and argue that true liquids of intermediate composition (59 to 66 wt% SiO2) are far less common in the subvolcanic reservoirs of arc volcanoes than is suggested by the abundance of erupted magma within this compositional range. This alternative view resolves several puzzling aspects of arc volcanism and provides important clues to the integration of plutonic and volcanic records. A large proportion of the magmas erupted at continental arc volcanoes are andesites, which are regarded as a major component in the formation of continental crust — consequently, it is important to understand andesite Petrogenesis. Here, an alternative view of andesite Petrogenesis is presented, based on a review of quenched glassy melt inclusions trapped in phenocrysts, whole-rock chemistry, and high-pressure and high-temperature experiments; this new view resolves several puzzling aspects of arc volcanism. Andesites represent a large proportion of the magmas erupted at continental arc volcanoes and are regarded as a major component in the formation of continental crust1. Andesite Petrogenesis is therefore fundamental in terms of both volcanic hazard and differentiation of the Earth. Andesites typically contain a significant proportion of crystals showing disequilibrium petrographic characteristics indicative of mixing or mingling between silicic and mafic magmas, which fuels a long-standing debate regarding the significance of these processes in andesite Petrogenesis2 and ultimately questions the abundance of true liquids with andesitic composition. Central to this debate is the distinction between liquids (or melts) and magmas, mixtures of liquids with crystals, which may or may not be co-genetic. With this distinction comes the realization that bulk-rock chemical analyses of petrologically complex andesites can lead to a blurred picture of the fundamental processes behind arc magmatism. Here we present an alternative view of andesite Petrogenesis, based on a review of quenched glassy melt inclusions trapped in phenocrysts, whole-rock chemistry, and high-pressure and high-temperature experiments. We argue that true liquids of intermediate composition (59 to 66 wt% SiO2) are far less common in the sub-volcanic reservoirs of arc volcanoes than is suggested by the abundance of erupted magma within this compositional range. Effective mingling within upper crustal magmatic reservoirs obscures a compositional bimodality of melts ascending from the lower crust, and masks the fundamental role of silicic melts (≥66 wt% SiO2) beneath intermediate arc volcanoes. This alternative view resolves several puzzling aspects of arc volcanism and provides important clues to the integration of plutonic and volcanic records.

  • a dearth of intermediate melts at subduction zone volcanoes and the Petrogenesis of arc andesites
    Nature, 2009
    Co-Authors: Olivier Reubi, Jonathan D. Blundy
    Abstract:

    Andesites represent a large proportion of the magmas erupted at continental arc volcanoes and are regarded as a major component in the formation of continental crust. Andesite Petrogenesis is therefore fundamental in terms of both volcanic hazard and differentiation of the Earth. Andesites typically contain a significant proportion of crystals showing disequilibrium petrographic characteristics indicative of mixing or mingling between silicic and mafic magmas, which fuels a long-standing debate regarding the significance of these processes in andesite Petrogenesis and ultimately questions the abundance of true liquids with andesitic composition. Central to this debate is the distinction between liquids (or melts) and magmas, mixtures of liquids with crystals, which may or may not be co-genetic. With this distinction comes the realization that bulk-rock chemical analyses of petrologically complex andesites can lead to a blurred picture of the fundamental processes behind arc magmatism. Here we present an alternative view of andesite Petrogenesis, based on a review of quenched glassy melt inclusions trapped in phenocrysts, whole-rock chemistry, and high-pressure and high-temperature experiments. We argue that true liquids of intermediate composition (59 to 66 wt% SiO(2)) are far less common in the sub-volcanic reservoirs of arc volcanoes than is suggested by the abundance of erupted magma within this compositional range. Effective mingling within upper crustal magmatic reservoirs obscures a compositional bimodality of melts ascending from the lower crust, and masks the fundamental role of silicic melts (>/=66 wt% SiO(2)) beneath intermediate arc volcanoes. This alternative view resolves several puzzling aspects of arc volcanism and provides important clues to the integration of plutonic and volcanic records.

Patrick Michel - One of the best experts on this subject based on the ideXlab platform.

  • Comment on “Parent body depth-pressure-temperature relationships and the style of the ureilite anatexis” by P. H. Warren (MAPS 47:209–227)
    Meteoritics & Planetary Science, 2013
    Co-Authors: Cyrena Anne Goodrich, Lionel Wilson, James A. Van Orman, Patrick Michel
    Abstract:

    Ureilites are carbon-rich ultramafic (olivine + dominantly low-Ca pyroxene) achondrites with poorly understood Petrogenesis. One major problem concerns the origin of extensive variation in FeO content (olivine core Fo values ranging from approximately 75 to 95) among the individual ureilites. The two main competing hypotheses to explain this variation are: (1) equilibrium smelting, in which ureilite Fo values were established by pressure-dependent (depth-linked) carbon redox reactions on the ureilite parent body during partial melting; or (2) nebular inheritance, in which the variation in FeO contents was derived from ureilite precursors and was preserved during partial melting. The paper “Parent body depth-pressure-temperature relationships and the style of the ureilite anatexis” by Warren (2012) discusses a series of topics related to ureilite Petrogenesis. In each case, an argument is presented within the context of smelting versus nonsmelting models. Collectively, these arguments create the impression that there are many valid arguments against smelting. The purpose of this comment is to point out flaws in some of these arguments, and/or to show that the issues they address are independent of smelting versus nonsmelting models. Both equilibrium smelting and nebular inheritance (simple anatexis) models face challenges in explaining all the properties of ureilites, but both remain viable.

  • comment on parent body depth pressure temperature relationships and the style of the ureilite anatexis by p h warren maps 47 209 227
    Meteoritics & Planetary Science, 2013
    Co-Authors: Cyrena Anne Goodrich, Lionel Wilson, James A. Van Orman, Patrick Michel
    Abstract:

    Ureilites are carbon-rich ultramafic (olivine + dominantly low-Ca pyroxene) achondrites with poorly understood Petrogenesis. One major problem concerns the origin of extensive variation in FeO content (olivine core Fo values ranging from approximately 75 to 95) among the individual ureilites. The two main competing hypotheses to explain this variation are: (1) equilibrium smelting, in which ureilite Fo values were established by pressure-dependent (depth-linked) carbon redox reactions on the ureilite parent body during partial melting; or (2) nebular inheritance, in which the variation in FeO contents was derived from ureilite precursors and was preserved during partial melting. The paper “Parent body depth-pressure-temperature relationships and the style of the ureilite anatexis” by Warren (2012) discusses a series of topics related to ureilite Petrogenesis. In each case, an argument is presented within the context of smelting versus nonsmelting models. Collectively, these arguments create the impression that there are many valid arguments against smelting. The purpose of this comment is to point out flaws in some of these arguments, and/or to show that the issues they address are independent of smelting versus nonsmelting models. Both equilibrium smelting and nebular inheritance (simple anatexis) models face challenges in explaining all the properties of ureilites, but both remain viable.

S. P. Turner - One of the best experts on this subject based on the ideXlab platform.

Fukun Chen - One of the best experts on this subject based on the ideXlab platform.

  • Different melting conditions and Petrogenesis of peraluminous granites in western Qinling, China, and tectonic implications
    Lithos, 2019
    Co-Authors: Jingzhao Dou, Wolfgang Siebel, Fukun Chen
    Abstract:

    Abstract The Qinling orogen records the prolonged amalgamation history between the North China Block (NCB) and the South China Block (SCB) accompanied by major granitoid intrusions during the Triassic. However, the Petrogenesis of these granitoids, especially that of the peraluminous granites, remains a matter of debate. Detailed study of these peraluminous granites, which are the products of crustal melting, will give insights into the melting process and Petrogenesis of peraluminous magmas and will further constrain the regional geological evolution. In this study, Xiahe (XH) tourmaline-bearing two-mica granite and Baijiazhuang (BJZ) two-mica granite were selected for systematic analysis of their mineralogy, petrology, zircon U-Pb geochronology, and geochemistry. The zircon U-Pb dating showed that the XH and BJZ granites were emplaced at approximately 242 Ma and approximately 214 Ma, respectively. The presence of muscovite and tourmaline, high peraluminosity at >1.1, low oxygen fugacity (ƒO2) conditions below the fayalite–magnetite–quartz (FMQ) buffer, and low zircon saturation temperatures indicate sedimentary protolith (S-type) granitic affinity. The low CaO/Na2O ratios