Peraluminous granites: the effect of alumina on melt composition and coexisting minerals

1992 ◽  
pp. 409-416 ◽  
Author(s):  
François Holtz ◽  
Wilhelm Johannes ◽  
Michel Pichavant
Keyword(s):  
Peraluminous Granites ◽  
Melt Composition

Peraluminous granites: the effect of alumina on melt composition and coexisting minerals

1992 ◽  
Vol 83 (1-2) ◽  
pp. 409-416 ◽  
Author(s):  
François Holtz ◽  
Wilhelm Johannes ◽  
Michel Pichavant
Keyword(s):  
Primary Field ◽  
Liquidus Phase ◽  
Al Content ◽  
Peraluminous Granites ◽  
High Al Content ◽  
Melt Composition ◽  
Liquidus Temperatures ◽  
Phase Relationships

ABSTRACTLiquidus phase relationships at H2O-saturated and -undersaturated conditions and 2 kbar in the systems Qz-Or-Ab (SiO2-KAlSi3O8-NaAlSi3O8), Qz-Or-Ab-Al2O3, and subsystems are compared and discussed. In the peraluminous systems (i.e. when melts are saturated with respect to mullite) the liquidus temperatures are lowered by 40-55°C for compositions in the quartz primary field and by 15-25°C for cotectic compositions. The composition of the Qz-Ab eutectic and of the minimum are slightly shifted towards more Qz-rich compositions (minimum composition at P(H2O) = 2 kbar in the system Qz-Or-Ab-A12O3, saturated with respect to mullite: Qz40Or23Ab37). In melts saturated with sillimanite or mullite, the effect of high Al content may be lower for the Qz-Or than for the Qz-Ab eutectic.The depression of the liquidus temperatures may be partly related to the higher H2O solubility in melts saturated with respect to mullite. The solubility of H2O in a melt with a composition of Qz28Or34Ab38 at 2 kbar and 800°C is 5·77 ± 0·15 wt% H2O and 6·36 ± 0·30 wt% H2O in a melt with the same Qz/Or/Ab proportions but saturated with respect to mullite.The effect of high Al contents on the Mg and Fe contents of Ca-free granite melts was investigated at 775°C-3 kbar (melts coexisting with phlogopite), and at 820°C-2 kbar (melts coexisting with biotite and spinel), under NNO buffer conditions. Less than 0·15 wt% MgO is incorporated in subaluminous melts coexisting with phlogopite, whereas peraluminous melts (2·9 wt% normative corundum) contain 0·6–0·7 wt% MgO. A similar behaviour of the MgO content is observed for melts coexisting with biotite. In contrast, no significant effect of high Al contents on the FeO content of melt coexisting with biotite was observed. This suggests that the Fe/Mg ratio may be significantly lower in peraluminous than in subaluminous granitic melts.

Metallographic analysis of M2 high speed steel granules

2019 ◽  
pp. 78-85
Author(s):  
L. E. Afanasieva
Keyword(s):  
Solid Solution ◽  
Cellular Structure ◽  
High Speed ◽  
Solution Structure ◽  
Supersaturated Solid Solution ◽  
High Speed Steel ◽  
Metallographic Analysis ◽  
M2 High Speed Steel ◽  
Melt Composition

The article is devoted to the metallographic analysis of the M2 high-speed steel granules. The study is based on the investigation of the microstructure of the M2 high-speed steel granules obtained by melt atomization. It is demonstrated that granules of similar size can harden both by chemically separating and chemically non-separating mechanism. These last ones have supersaturated solid solution structure of the liquid melt composition, a dispersed dendritic-cellular structure and an increased microhardness HV = 10267±201 MPa.

Emergence of continents above sea‐level influences sediment melt composition

Terra Nova ◽  
2021 ◽  
Author(s):  
J. Liebmann ◽  
C.J. Spencer ◽  
C.L. Kirkland ◽  
C.E. Bucholz ◽  
X. He ◽  
...  
Keyword(s):  
Sea Level ◽  
Melt Composition

scholarly journals New insights on Br speciation in volcanic glasses and structural controls on halogen degassing

2020 ◽  
Vol 105 (6) ◽  
pp. 795-802 ◽  
Author(s):  
Marion Louvel ◽  
Anita Cadoux ◽  
Richard A. Brooker ◽  
Olivier Proux ◽  
Jean-Louis Hazemann
Keyword(s):  
Atmospheric Chemistry ◽  
Divalent Cations ◽  
Stratospheric Ozone ◽  
High Energy ◽  
Aluminosilicate Glass ◽  
High Energy Resolution ◽  
Magma Chambers ◽  
Structural Controls ◽  
Volcanic Glasses ◽  
Melt Composition

Abstract The volcanic degassing of halogens, and especially of the heavier Br and I, received increased attention over the last 20 years due to their significant effect on atmospheric chemistry, notably the depletion of stratospheric ozone. While the effect of melt composition on halogen diffusion, solubility, or fluid-melt partitioning in crustal magma chambers has been thoroughly studied, structural controls on halogen incorporation in silicate melts remain poorly known, with only few studies available in simplified borosilicate or haplogranite compositions. Here, we demonstrate that high-energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD-XAS) with a crystal analyzer spectrometer (CAS) is well-suited for the study of Br speciation in natural volcanic glasses which can contain lower Br concentrations than their laboratory analogs. Especially, HERFD-XAS results in sharper and better-resolved XANES and EXAFS features than previously reported and enables detection limits for EXAFS analysis down to 100 ppm when previous studies required Br concentrations above the 1000 ppm level. XANES and EXAFS analyses suggest important structural differences between synthetic haplogranitic glass, where Br is surrounded by Na and next-nearest oxygen neighbors, and natural volcanic glasses of basaltic to rhyodacitic compositions, where Br is incorporated in at least three distinct sites, surrounded by Na, K, or Ca. Similar environments, involving both alkali and alkaline earth metals have already been reported for Cl in Ca-bearing aluminosilicate glass and our study thus underlines that the association of Br with divalent cations (Ca2+) has been underestimated in the past due to the use of simplified laboratory analogs. Overall, similarities in Cl and Br structural environments over a large array of compositions (46–67 wt% SiO2) suggest that melt composition alone may not have a significant effect on halogen degassing and further support the coupled degassing of Cl and Br in volcanic systems.

The Monchegorsk Intrusion: Reconstruction (Parent Magma (Melt) Composition, P–T Conditions, and Intrusion Thickness)

2021 ◽  
Vol 76 (3) ◽  
pp. 300-315
Author(s):  
V. S. Semenov ◽  
E. V. Koptev–Dvornikov ◽  
S. V. Semenov ◽  
S. I. Korneev
Keyword(s):  
Parent Magma ◽  
Melt Composition ◽  
Magma Melt

scholarly journals The effect of melt composition and oxygen fugacity on manganese partitioning between apatite and silicate melt

2019 ◽  
Vol 506 ◽  
pp. 162-174 ◽  
Author(s):  
T.N. Stokes ◽  
G.D. Bromiley ◽  
N.J. Potts ◽  
K.E. Saunders ◽  
A.J. Miles
Keyword(s):  
Oxygen Fugacity ◽  
Silicate Melt ◽  
Melt Composition

scholarly journals Equilibrium electrochemical synthesis diagrams of systems, forming homogeneous alloys and compounds

2003 ◽  
Vol 39 (1-2) ◽  
pp. 383-405 ◽  
Author(s):  
G. Kaptay
Keyword(s):  
Thermodynamic Parameter ◽  
Electrochemical Synthesis ◽  
Equilibrium Phase ◽  
Equilibrium Composition ◽  
Alloy Formation ◽  
Fixed Temperature ◽  
Synthesis Conditions ◽  
Melt Composition ◽  
Alloys And Compounds ◽  
Non Equilibrium

In the present paper thermodynamic limitations will be derived and summarized in the form of Equilibrium Electrochemical Synthesis (EES) diagrams, in order to predict the composition of the equilibrium phase, synthesized by galvanostatic co-deposition of components on inert electrodes. As a thermodynamic parameter, a difference of deposition potentials of pure components ( ?E) on inert cathodes is used (this parameter is a function of melt composition and temperature). Generally, the EES diagram predicts the equilibrium composition of the alloy as function temperature and ?E. However, for systems with homogeneous alloy formation the composition- ?E diagrams, drawn at a fixed temperature are more informative. As examples EES diagrams are constructed for the liquid Mg-Nd alloy, for some A(III)-B(V) (where A = Al, Ga, In and B = As, Sb), Si-C and for the Al-Ti system. For the Al-rich part of the Al-Ti system, also a semi-schematic non-equilibrium ES diagram is constructed. Based on these diagrams, the synthesis conditions of various phases has been discussed.

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