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23 results on '"Heinrich, Christoph"'

2. Copper partitioning between silicate melts and amphibole: Experimental insight into magma evolution leading to porphyry copper ore formation

Author

Hsu, Ying-Jui, Zajacz, Zoltán, Ulmer, Peter, and Heinrich, Christoph A.

Subjects
Copper, Partition coefficient, Porphyry deposit, Amphibole, Magma evolution, Ore genesis
Abstract

A series of piston cylinder experiments were conducted to determine the partition coefficient of Cu between amphibole and andesitic to rhyolitic silicate melts. The experiments were run at T = 740–990 °C, P = 0.7 GPa, oxygen fugacity (fO2) ranging from that of the Ni-NiO buffer (NNO) to 2.3 log units higher (NNO + 2.3 and dissolved water in variable concentrations (under-saturated to saturated conditions). Fixed metal activities were imposed by using Au97Cu3 and Au92Cu8 alloy capsules, which allowed simultaneously determination of Cu solubility. Our data demonstrate that Cu solubilities in both the silicate melt and amphibole decrease with decreasing temperature. The solubility of Cu decreases by a factor of 6 from 990 to 740 °C in equilibrium with andesitic to rhyolitic melt compositions. The average amphibole/silicate melt partition coefficient of Cu [DCu (amph/melt)] is 0.066 ± 0.006, and is essentially constant without showing any correlation with silicate melt composition, dissolved water concentration, temperature or fO2. The low DCu (amph/melt) value suggests that amphibole crystallizing at any stage of calc-alkaline magma evolution is unable to scavenge a significant fraction of the initially available Cu from the melt. However, DCu (amph/melt) is high enough to yield precisely measurable Cu concentrations in natural amphiboles. As DCu (amph/melt) remains constant along the liquid line of descent of calc-alkaline magmas, amphibole compositions may thus be used as a proxy to monitor the evolution of the Cu concentration in the silicate melt (not the bulk magma if sulfide is present). This may be useful for understanding the metallogenic evolution of intrusive rocks, in which silicate melt inclusions in minerals are generally absent. As most porphyry-type Cu ore deposits are associated with upper crustal intrusions, in-situ microanalysis of inclusion-free amphiboles in such rocks may help understand ore genesis and might also be used in mineral exploration to assess the fertility of prospective magmatic systems. ISSN:0009-2541 ISSN:1872-6836

Published
2017

4. Microanalysis of S, Cl, and Br in fluid inclusions by LA-ICP-MS

Author

Seo, Jung Hun, Guillong, Marcel, Aerts, Maarten, Zajacz, Zoltán, and Heinrich, Christoph A.

Subjects
Halogen, Chlorine, LA-ICP-MS, Bromine, Fluid inclusion, Sulfur
Abstract

Chemical Geology, 284 (1-2), ISSN:0009-2541, ISSN:1872-6836

Published
2011

13. Influence of the electrical field applied during thermal cycling on the conductivity of LLDPE/CNT composites

Author

Diana Sannino, Heinrich Christoph Neitzert, Paolo Ciambelli, Giuliana Gorrasi, Vittoria Vittoria, Maria Sarno, and Manuela Ferrara

Subjects
Nanocomposite, Materials science, Temperature cycling, Carbon nanotube, Conductivity, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, law.invention, Linear low-density polyethylene, Differential scanning calorimetry, Electrical resistivity and conductivity, law, Composite material, Temperature coefficient
Abstract

The effect of the electrical field on the conductivity of linear low-density polyethylene/carbon nanotubes/ (LLDPE/CNT) composites during temperature cycling has been investigated. Under applied voltage a positive resistivity temperature coefficient was observed during heating already at low (2–3 wt%) CNT content, followed by a large negative temperature coefficient during cooling whose value depends on the applied voltage. The resistivity values after thermal cycling were markedly lower, while they slightly increased in the absence of an electrical field. The effects of thermal cycling on structural and physical properties of the composites have been evaluated by X-ray diffraction and differential scanning calorimetry.

Published
2006

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