Search results for "MELT"

Partial melting of metabasic rocks in Val Strona di Omegna, Ivrea Zone, northern Italy

2014

Field and petrographic observations combined with major and trace element bulk rock geochemistry show that metabasic rocks within Val Strona di Omegna in the central Ivrea Zone partially melted during granulite facies regional metamorphism. A transition from granoblastic amphibolite facies metabasic rocks at the lowest metamorphic grades to metatexitic and diatexitic migmatites in the granulite facies records the effects of in situ fluid-absent partial melting. Coarse-grained euhedral clinopyroxene porphyroblasts within leucosomes are consistent with anatexis via incongruent fluid-absent melting reactions consuming hornblende, plagioclase and quartz to form clinopyroxene and melt. Field obs…

Phase equilibrium constraints on a deep crustal metamorphic field gradient: metapelitic rocks from the Ivrea Zone (NW Italy)

2011

The metamorphic rocks of the Ivrea Zone in NW Italy preserve a deep crustal metamorphic field gradient. Application of quantitative phase equilibria methods to metapelitic rocks provides new constraints on the P–T conditions recorded in Val Strona di Omegna, Val Sesia and Val Strona di Postua. In Val Strona di Omegna, the metapelitic rocks show a structural and mineralogical change from mica‐schists with the common assemblage bi–mu–sill–pl–q–ilm ± liq at the lowest grades, through metatexitic migmatites (g–sill–bi–ksp–pl–q–ilm–liq) at intermediate grades, to complex diatexitic migmatites (g–sill–ru–bi–ksp–pl–q–ilm–liq) at the highest grades. Partial melting in the metapelitic rocks is consi…

STOP 3: Late-glacial and early postglacial environmental processes and the history of the River Triečupīte valley and surroundings, in the foreland o…

2014

Archaean Intracrustal Differentiation from Partial Melting of Metagabbro--Field and Geochemical Evidence from the Central Region of the Lewisian Comp…

2012

The central region of the mainland Lewisian gneiss complex of NW Scotland is a granulite-facies migmatite terrane. With the exception of ultramafic and rare calc-silicate rocks, all other lithologies partially melted during Neoarchaean, ultrahigh-temperature (Badcallian) metamorphism. The clearest evidence is preserved within large layered mafic^ultramafic bodies that exhibit macroscopic features diagnostic of anatexis. In situ partial melting of metagabbroic rocks produced patches and sheets of coarse-grained plagioclase-rich leucosome containing euhedral peritectic clinopyroxene.These leucosomes connect with larger, laterally continuous tonalite or trondhjemite sheets that record segregat…

Partial Melting and Counterclockwise P T Path of Subducted Oceanic Crust (Sierra del Convento Melange, Cuba)

2007

Phase equilibria modelling of kyanite-bearing anatectic paragneisses from the central Grenville Province

2008

Kyanite-bearing paragneisses from the Manicouagan Imbricate Zone and its footwall (high-P belt of the central Grenville Province) preserve evidence of partial melting with development of metamorphic textures involving biotite-garnet ± kyanite ± plagioclase ± K-feldspar-quartz. Garnet in these rocks displays a variety of zoning patterns with respect to Ca. Pseudosection modelling in the Na O-CaO-K O-FeO-MgO-Al O - SiO -H O-TiO -O (NCKFMASHTO) system using measured bulk rock compositions accounts for the textural evolution of two aluminous and two sub-aluminous samples from the presumed thermal peak to conditions at which retained melt solidified. The prograde features are best explained by p…

A year in the life of an aluminous metapelite xenolith—The role of heating rates, reaction overstep, H2O retention and melt loss

2011

Abstract Xenoliths of aluminous metapelite within the Platreef magmatic rocks of the Bushveld Complex, South Africa, are mineralogically and texturally zoned, with coarse-grained margins rich in acicular corundum, spinel and feldspar and cores rich in finer-grained aluminosilicate and cordierite. Xenoliths exhibiting remarkably similar features occur within other intrusions, suggesting a common origin. Using a single 3 m wide xenolith as a case study, a model is proposed to explain their petrogenesis. Mineral equilibria calculations in the NCKFMASHTO system show that the thermal stability of the solid phases, in particular corundum, is highly sensitive to the quantity of H 2 O retained in t…

Hydrogen bond studies on n-pentanol and 2-methyl-2-butanol by Raman spectroscopy

1986

Polarized Raman spectra of n-pentanol and its isomer 2-methyl-2-butanol are obtained in the liquid phase near the melting points and at superheated temperatures. The measurements are performed in the intramolecular O-H stretching region. Our analysis of the Raman data provides an interpretation of the spectral features in terms of symmetric O-H bands, originated by various degrees of intermolecular coupling, for which mechanism is different for the two isomers. Temperature dependence of the spectra is also discussed in terms of available structural and dynamical models for these H-bonded liquids.

Eigenschaften isomerer Methoxylderivate der phenolischen Mehrkernverbindungen

1971

Es wurden 21 Mehrkernverbindungen hergestellt, deren phenolische Hydroxylgruppen teilweise oder vollstandig methyliert waren. Mit steigendem Methylierungsgrad fallen die Schmelzpunkte der Ather mit einer Ausnahme regelmasig ab. Die molaren dekadischen Extinktionskoeffizienten der Maxima in den UV-Spektren der Ather werden, verglichen mit den Stammverbindungen, mit zunehmendem Methylierungsgrad kleiner. Die zunehmende Methylierung ist im Vergleich mit konstantbleibenden Banden der IR-Spektren an ab- und zunehmenden Banden zu verfolgen. Isomere (metamere) Methylather mit noch freien phenolischen Hydroxylgruppen unterscheiden sich im Schmelzpunkt, in ihren UV- und IR-Spektren. Die Unterschiede…

Structure and Stability of Racemic and Enantiopure Pimobendan Monohydrates: On the Phenomenon of Unusually High Stability

2017

Study of structures and physicochemical properties of racemic (rac-H) and enantiopure (enant-H) hydrates of the active pharmaceutical ingredient pimobendan revealed that both hydrates have highly similar crystal structures and exhibit unusually high stability. Both structures contain identical two-dimensional layers and very similar conformations. The most significant difference is the stacking of these layers. The high stability of both hydrates appeared as extremely low solubility over a wide temperature range as well as an exceptionally high dehydration temperature and melting point. Study of the dehydration process showed that both hydrates have different activation energies of dehydrat…