scholarly journals Effect of melt composition on crustal carbonate assimilation: Implications for the transition from calcite consumption to skarnification and associated CO2degassing

2016 ◽  
Vol 17 (10) ◽  
pp. 3893-3916 ◽  
Author(s):  
Laura B. Carter ◽  
Rajdeep Dasgupta
Keyword(s):  
Melt Composition ◽  
Carbonate Assimilation

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.

scholarly journals Tephrostratigraphy and Magma Evolution Based on Combined Zircon Trace Element and U-Pb Age Data: Fingerprinting Miocene Silicic Pyroclastic Rocks in the Pannonian Basin

2021 ◽  
Vol 9 ◽  
Author(s):  
Réka Lukács ◽  
Marcel Guillong ◽  
Olivier Bachmann ◽  
László Fodor ◽  
Szabolcs Harangi
Keyword(s):  
Trace Element ◽  
Partition Coefficients ◽  
Pannonian Basin ◽  
Trace Element Content ◽  
Element Content ◽  
Published Data ◽  
Concentration Data ◽  
Pyroclastic Deposits ◽  
Silicic Volcanic ◽  
Melt Composition

We present a novel approach to use zircon as a correlation tool as well as a monitor for magma reservoir processes in silicic volcanic systems. Fingerprinting eruption products based on trace element content and U-Pb dates of zircon offers a promising, previously underestimated tephra correlation perspective, particularly in cases where the main minerals and glass are altered. Using LA-ICP-MS analyses, a rapid and cost-effective method, this study presents U-Pb dates and trace element concentration data of more than 950 zircon crystals from scattered occurrences of early to mid-Miocene silicic ignimbrites in the northern Pannonian Basin, eastern-central Europe. This magmatic phase produced >4000 km3 of erupted material, which provide unique stratigraphic marker horizons in central and southern Europe. The newly determined zircon U-Pb eruption ages for the distal pyroclastic deposits are between 17.5 and 14.3 Ma, comparable with the previously published ages of the main eruptive events. Multivariate discriminant analysis of selected trace element concentrations in zircon proved to be useful to distinguish the main volcanic units and to correlate the previously ambiguously categorized pyroclastic deposits with them. Using the zircon trace element content together with published glass data from crystal-poor ignimbrites, we determined the zircon/melt partition coefficients. The obtained values of the distinct eruption units are very similar and comparable to published data for silicic volcanic systems. This suggests that zircon/melt partition coefficients in calc-alkaline dacitic to rhyolitic systems are not significantly influenced by the melt composition at >70 wt% SiO2 at near solidus temperature. The partition coefficients and zircon trace element data were used to calculate the equilibrium melt composition, which characterizes the eruption products even where glass is thoroughly altered or missing. Hence, our results provide important proxies for tephrostratigraphy in addition to yielding insights into the complex processes of silicic magma reservoirs.

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