Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
P-T-X data on P2(1)/c-clinopyroxenes and their displacive phase transitions
Autore:
Arlt, T; Kunz, M; Stolz, J; Armbruster, T; Angel, RJ;
Indirizzi:
Univ Bayreuth, Bayer Geoinst, D-95440 Bayreuth, Germany Univ Bayreuth Bayreuth Germany D-95440 eoinst, D-95440 Bayreuth, Germany ETH Zentrum, Labor Kristallog, CH-8092 Zurich, Switzerland ETH Zentrum Zurich Switzerland CH-8092 llog, CH-8092 Zurich, Switzerland Univ Bern, Lab Chem & Mineral Kristallog, CH-3012 Bern, Switzerland Univ Bern Bern Switzerland CH-3012 Kristallog, CH-3012 Bern, Switzerland
Titolo Testata:
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
fascicolo: 1, volume: 138, anno: 2000,
pagine: 35 - 45
SICI:
0010-7999(200001)138:1<35:PDOPAT>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
CLINOENSTATITE TRANSITION; CRYSTAL-CHEMISTRY; 10 GPA; CLINOPYROXENES; RAY; PYROXENES; EQUATION; STATE; CLINOFERROSILITE; SILICATES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
44
Recensione:
Indirizzi per estratti:
Indirizzo: Angel, RJ Univ Bayreuth, Bayer Geoinst, POB 101251, D-95440 Bayreuth, Germany Univ Bayreuth POB 101251 Bayreuth Germany D-95440 euth, Germany
Citazione:
T. Arlt et al., "P-T-X data on P2(1)/c-clinopyroxenes and their displacive phase transitions", CONTR MIN P, 138(1), 2000, pp. 35-45

Abstract

The P2(1)/c clinopyroxene kanoite (ideally MnMgSi2O6) was studied as a function of pressure and temperature using powder X-ray diffraction, differential scanning calorimetry (DSC) and optical methods. The temperature of the P2(1)/c to high-temperature (HT) C2/c transition ranges from 425 degrees C in endmember MnMgSi2O6 to 125 degrees C in natural samples with arn aegirine component. Compiling pigeonite and clinoenstatite-clinoferrosilite literature data, the temperature of the transformation was found to decrease linearly with M2 cation size. A synchrotron powder diffraction study in a heated diamond-anvil cell (DAC) yielded compression and thermal expansion data for low kanoite of composition Mn1.2Mg0.4Fe0.4Si2O6 The high-pressure (HP) phase transition from P2(1)/c to HP C2/c was reversed at 5.8 GPa at 417 degrees C. The high-temperature phase transition from P2(1)/c to HT C2/c was rather indistinct and occurred at approximately 530 degrees C and 0.76 Cpa. In a separate experiment, the HT transition was observed optically in a hydrothermal DAC between 0.0 and 0.4 GPa. The in-situ P-T data of both experiments yielded an increase in transition temperature with increasing pressure (approx. 149 degrees C/GPa) and suggest a change in character of the transition from first order to continuous with increasing pressure. The data indicate that the HT C2/c and HP C2/c polymorphs are distinct phases with different stability fields. Since the high-temperature and the high-pressure polymorphs of kanoite were shown to be isotypic with other low-Ca clinopyroxenes such as the (Mg,Fe)SiO3 series, the conclusions we draw from this study are valid for all clinopyroxenes with small (< 0.88 Angstrom) M1 and M2 cation sizes. The petrologic implications of these conclusions for the occurrence of "clinoenstatite" in the Alpe Arami peridotite are discussed.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 13/07/20 alle ore 07:55:59