Abstract. Modern-style plate tectonics is characterised by the global operation of cold and deep subduction involving blueschist facies ultrahigh-pressure metamorphism. This has been a common process since Neoproterozoic, but couple studies indicate similar processes were active in Paleoproterozoic, at least on local scale. Particularly conspicuous are extreme conditions ∼ 7 GPa thermal gradien...

Abstract Continental arcs in active continental margins (especially deep-seated arc magmatism, anatexis, and metamorphism) can be extremely significant evaluating continent building processes. In this contribution, a Paleozoic section is constructed based on coeval granulite-facies metamorphism, magmatism the northern margin of Qilian Block, which record two episodes crust growth. The deeper la...

Highly cracked and isomerized archaeal lipids and bacterial lipids, structurally changed by thermal stress, are present in solvent extracts of 2,707- to 2,685-million-year-old (Ma) metasedimentary rocks from Timmins, ON, Canada. These lipids appear in conventional gas chromatograms as unresolved complex mixtures and include cyclic and acyclic biphytanes, C36-C39 derivatives of the biphytanes, a...

Shock metamorphism in ordinary chondrites allows for reconstructing impact events between asteroids the main asteroid belt. Shock-darkening of occurs at onset complete shock melting rock (>70 GPa) or injection sulfide and metal melt into cracks within solid silicates (\sim 50 GPa). Darkening masks diagnostic silicate features observed reflectance spectrum S-complex so they appear similar to C/X...

Microcrystals of coesite and stishovite were discovered as inclusions in amorphous silica grains in shocked melt pockets of a lunar meteorite Asuka-881757 by micro-Raman spectrometry, scanning electron microscopy, electron back-scatter diffraction, and transmission electron microscopy. These high-pressure polymorphs of SiO(2) in amorphous silica indicate that the meteorite experienced an equili...

Metamorphism associated with orogenesis provides a mineral record that may be inverted to yield ambient apparent thermal gradients. On modern Earth, tectonic settings with lower thermal gradients are characteristic of subduction zones whereas those with higher thermal gradients are characteristic of backarcs and orogenic hinterlands. The duality of thermal environments reflects the asymmetry of...

late neoproterozoic-early cambrian schists have been occurred in southwest of zanjan city from the soltanieh belt. the soltanieh belt in northwest of iran is uplifted basement of precambrian-paleozoic in main central iran zone and includes outcrops of precambrian, paleozoic and mesozoic formations. late neoproterozoic-early cambrian schists, the oldest stratigraphy unit in the region, consist o...

Please cite this article in press as: Schaefer, L., Fe implications for the composition of asteroids. Ic We used chemical equilibrium calculations to model thermal metamorphism of ordinary chondritic material as a function of temperature, pressure, and trace element abundance and use our results to discuss volatile mobilization during thermal metamorphism of ordinary chondrite parent bodies. We...

ABSTRACT This paper presents and discusses the results of phase diagram (Perple_X) diffusion modelling (CZGM, or Compositional Zoning its Modification by diffusion) to constrain P–T path metamorphism. The approach is based on best fits between zoning profile in measured garnet that obtained intersections isopleths calculated using whole rock bulk composition. model was applied garnets natural r...