Comparative compressibility of end-member feldspars

Angel, R. J.; Hazen, Robert M.; McCormick, Tamsin C.; Prewitt, C. T.; Smyth, Joseph R.

doi:10.1007/bf00311034

Cited by 98 publications

(51 citation statements)

References 20 publications

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“…Similarly, the slowest P-wave direction shifts from (100) in An0 to 55° from the (100) pole in An100 (Fig. 6a), consistent with findings of Angel et al (1988). The redistribution of Al atoms and bonds can also help explain this rotation with increasing An content, but it may not account for the much larger shift of 55° suggesting that either the increased amount of Al and/or Ca and associated bonds are responsible.…”

Section: Velocity Mapssupporting

confidence: 82%

“…6b), but compression experiments do. From compression experiments on analbite, Curetti et al (2011) found ordered low albite to be more anisotropic than disordered high albite, and in compression studies of single crystals in a diamond-anvil cell, Angel et al (1988) found An0 to be more anisotropic than An100. This is attributed to the redistribution of the more compressible Al-OSi bonds and corresponding T-O bond lengths associated with disorder (Downs et al 1994;Curetti et al 2011).…”

Section: Velocity Mapsmentioning

confidence: 99%

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Ab initio calculations of elastic constants of plagioclase feldspars

Kaercher

Militzer

Wenk

2014

American Mineralogist

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Plagioclase feldspars comprise a large portion of the Earth's crust and are very anisotropic, making accurate knowledge of their elastic properties important for understanding the crust's anisotropic seismic signature. However, except for albite, existing elastic constants for plagioclase feldspars are derived from measurements that cannot resolve the triclinic symmetry. We calculate elastic constants for plagioclase end-members albite NaAlSi 3 O 8 and anorthite CaAl 2 Si 2 O 8 and intermediate andesine/ labradorite NaCaAl 3 Si 5 O 16 using density functional theory to compare with and improve existing elastic constants and to study trends in elasticity with changing composition. We obtain elastic constants similar to measured elastic constants and find that anisotropy decreases with anorthite content.

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Section: Velocity Mapssupporting

confidence: 82%

Section: Velocity Mapsmentioning

confidence: 99%

Ab initio calculations of elastic constants of plagioclase feldspars

Kaercher

Militzer

Wenk

2014

American Mineralogist

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“…This decrease in compressibility with increasing Na/Na + K is a logical consequence of bulk modulus-volume relationships (Hazen and Finger 1982). In feldspar minerals, in both muscovite and phlogopite Angel et al (1988) also observed that the bulk modulus of albite is slightly greater than that of sanidine. Unfortunately, the only partial substitution of Na for K, together with the large errors in the polyhedral bulk moduli did not allow a clear difference between the K -O bulk moduli of K-Ms and Na-Ms to be established.…”

Section: )mentioning

confidence: 86%

High-pressure structural study of muscovite

Comodi

Zanazzi

1995

Phys Chem Minerals

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Abstract. The compressibility and structural variations of two 2M 1 muscovites having compositions (Nao.oyKo.90 Bao.o1E]o.oz)(All.84Tio.04Feo.ovMgo.o4)(Si3.02Alo.98) Olo (OH)2 (7 mole % paragonite) and (Nao.37Ko.60Do.03)(All.84Tio.02 Fe0.a0Mg0.06)(Si3.o3A10.97 ) O10(OH)2 (37 mole % paragonite) were determined at pressures between 1 bar and 35 kbar, by single-crystal X-ray diffraction using a Merrill-Bassett diamond anvil cell.Isothermal bulk moduli, setting K'= 4, were 490 and 540 (__+ 30) kbar for the Na-poor and Na-rich samples respectively. Both samples show highly anisotropic compressibility patterns, with fla:flb:flc= 1:1.15:3.95 for the Na-poor sample and fia:flb:flc=1:l.19:3.46 for the Narich one.HP structural refinements showed that the different compressibility was largely due to the partial substitution of Na for K in the interlayer region. Moreover, the different compressibility of the tetrahedral and octahedral layers, observed in both micas, increased the a rotation of the tetrahedral layer by about 2 ~ in 28 kbar, as also indicated by the evolution of interlayer cation bond lengths. This increases the repulsion of oxygens of the basal layers and between the high-charged cations of the tetrahedral layer. As a consequence, phengitic substitution, reducing c~ rotation, would increase the baric stability of mica.Comparison between the HP structures of muscovite and phlogopite indicated the lower compressibility of the latter, mainly due to the greater compressibility of the dioctahedral layer with respect to that of the trioctahedral layer.The H T and HP behaviour of di-and trioctahedral micas showed an anisotropy in the compressional pattern which was markedly greater than that observed in the dilatation pattern. This unexpected result was explained by the different evolution with P and Tof alkali-O bond lengths. By combining HP and H Tdata, a tentative equation of state of muscovite is proposed.

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“…The empirical pressure correction (P emp ) is computed at the static P (GPa) experimental volume of anorthite (Wainwright and Starkey, 1971;Fei, 1995), using an optimized P 1 unit cell and a 4 Â 2 Â 2 Monkhorst and Pack (1976) k-point grid. P emp is found to be 2.06 GPa (Krupka et al, 1979;Angel et al, 1988;Ita and Stixrude, 1992;Bass, 1995;Fei, 1995;Robie and Hemingway, 1995;Smyth and McCormick, 1995).…”

Section: Fpmd Simulation Detailsmentioning

confidence: 94%

Structure, thermodynamics, and diffusion in CaAl2Si2O8 liquid from first-principles molecular dynamics

Koker

2010

Geochimica et Cosmochimica Acta

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Comparative compressibility of end-member feldspars

Cited by 98 publications

References 20 publications

Ab initio calculations of elastic constants of plagioclase feldspars

Ab initio calculations of elastic constants of plagioclase feldspars

High-pressure structural study of muscovite

Structure, thermodynamics, and diffusion in CaAl2Si2O8 liquid from first-principles molecular dynamics

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