Abstract
Trace-element partition coefficients between plagioclase and coexisting glass/matrix have been determined for twenty-nine rhyodacite-rhyolite samples from nine volcanic centers. Strontium partition coefficients form two clear positive trends when plotted against the An content of plagioclase. One trend has a steep slope with DSr between 5.6 and 15.8 (T1), whereas the other trend has a gentle slope with DSr between 1.2 and 7.6 (T2). Barium partition coefficients show similar patterns: a steeply sloped trend is formed by samples with DBa between 1.6 and 8.8, and a gently sloped trend by samples with DBa <1. DSr and DBa in plagioclase correlate positively, and both DSr and DBa correlate positively with temperature. Samples with large DSr and DBa are all from rocks with <1 wt% CaO. These rocks are peraluminous and also have low total Sr and Ba. Partition coefficients for Sr and Ba are influenced by whole-rock CaO in high-Al rhyolite systems. Where these systems have low CaO, the opportunity increases for other divalent cations to enter the plagioclase structure. Strontium and Ba will then enter the M position of plagioclase to balance the charge deficiency caused by the substitution of Al for Si. Because of the potent influence of whole-rock composition on Sr and Ba partitioning for low CaO rocks, values of partition coefficients in petrogenetic modeling needs to be selected carefully.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Bonding preferences of non-bridging O atoms: Evidence from 17O MAS and 3QMAS NMR on calcium aluminate and low-silica Ca-aluminosilicate glasses
- BNa–BLi solid-solution in A-site-vacant amphiboles: synthesis and cation ordering along the ferri-clinoferroholmquistite–riebeckite join
- A new uranyl carbonate sheet in the crystal structure of fontanite, Ca[(UO2)3(CO3)2O2](H2O)6
- XANES calibrations for the oxidation state of iron in a silicate glass
- Dissolution of strontianite at high P-T conditions: An in-situ synchrotron X-ray fluorescence study
- Intergrown niobian rutile phases with Sc- and W-rich ferrocolumbite: An electron-microprobe and Rietveld study
- Bulk moduli and high-pressure crystal structures of minium, Pb3O4, determined by X-ray powder diffraction
- Slow oxygen diffusion rates in igneous zircons from metamorphic rocks
- Chemistry of grain boundaries in mantle rocks
- Heats of mixing of silicate liquid in the systems diopside-anorthite-akermanite, diopside-anorthite-forsterite, and diopside-silica
- High-pressure crystal structure of kosmochlor, NaCrSi2O6, and systematics of anisotropic compression in pyroxenes
- Monte Carlo simulations of ordering of Al, Fe, and Mg cations in the octahedral sheet of smectites and illites
- Influence of F content on the composition of Al-rich synthetic phlogopite: Part II. Probing the structural arrangement of aluminum in tetrahedral and octahedral layers by 27Al MQMAS and 1H/19F-27Al HETCOR and REDOR experiments
- Dawsonite: An inclusion mineral in quartz from the Tin Mountain pegmatite, Black Hills, South Dakota
- Hydrogen-bonded water in laumontite II: Experimental determination of site-specific thermodynamic properties of hydration of the W1 and W5 sites
- High P-T phase relations and stability of a (21)-hydrous clinopyribole in the system K2ONa2O- CaO-MgO-Al2O3-SiO2-H2O: An experimental study to 18 GPa
- The crystal chemistry of julgoldite-Fe3+ from Bombay, India, studied using synchrotron X-ray powder diffraction and 57Fe Mössbauer spectroscopy
- Partitioning of Sr, Ba, Rb, Y, and LREE between plagioclase and peraluminous silicic magma
- Infrared and TEM characterization of amphiboles synthesized near the tremolite-pargasite join in the ternary system tremolite-pargasite-cummingtonite
- Coupling between non-convergent ordering and transition temperature in the C2/c ↔ P21/c phase transition in pigeonite
- 57Fe Mössbauer-effect studies of Ca-rich, Fe-bearing clinopyroxenes: Part I. Paramagnetic spectra of magnesian hedenbergite
- 57Fe Mössbauer-effect studies of Ca-rich, Fe-bearing clinopyroxenes: Part II. Magnetic spectra of magnesian hedenbergite
- 57Fe Mössbauer-effect studies of Ca-rich, Fe-bearing clinopyroxenes: Part III. Diopside
- Letters. Aluminum substitution in MgSiO3 perovskite: Investigation of multiple mechanisms by 27Al NMR
- Studtite, [(UO2)(O2)(H2O)2](H2O)2: The first structure of a peroxide mineral
- Nanometer-scale measurements of iron oxidation states of cronstedtite from primitive meteorites
Articles in the same Issue
- Bonding preferences of non-bridging O atoms: Evidence from 17O MAS and 3QMAS NMR on calcium aluminate and low-silica Ca-aluminosilicate glasses
- BNa–BLi solid-solution in A-site-vacant amphiboles: synthesis and cation ordering along the ferri-clinoferroholmquistite–riebeckite join
- A new uranyl carbonate sheet in the crystal structure of fontanite, Ca[(UO2)3(CO3)2O2](H2O)6
- XANES calibrations for the oxidation state of iron in a silicate glass
- Dissolution of strontianite at high P-T conditions: An in-situ synchrotron X-ray fluorescence study
- Intergrown niobian rutile phases with Sc- and W-rich ferrocolumbite: An electron-microprobe and Rietveld study
- Bulk moduli and high-pressure crystal structures of minium, Pb3O4, determined by X-ray powder diffraction
- Slow oxygen diffusion rates in igneous zircons from metamorphic rocks
- Chemistry of grain boundaries in mantle rocks
- Heats of mixing of silicate liquid in the systems diopside-anorthite-akermanite, diopside-anorthite-forsterite, and diopside-silica
- High-pressure crystal structure of kosmochlor, NaCrSi2O6, and systematics of anisotropic compression in pyroxenes
- Monte Carlo simulations of ordering of Al, Fe, and Mg cations in the octahedral sheet of smectites and illites
- Influence of F content on the composition of Al-rich synthetic phlogopite: Part II. Probing the structural arrangement of aluminum in tetrahedral and octahedral layers by 27Al MQMAS and 1H/19F-27Al HETCOR and REDOR experiments
- Dawsonite: An inclusion mineral in quartz from the Tin Mountain pegmatite, Black Hills, South Dakota
- Hydrogen-bonded water in laumontite II: Experimental determination of site-specific thermodynamic properties of hydration of the W1 and W5 sites
- High P-T phase relations and stability of a (21)-hydrous clinopyribole in the system K2ONa2O- CaO-MgO-Al2O3-SiO2-H2O: An experimental study to 18 GPa
- The crystal chemistry of julgoldite-Fe3+ from Bombay, India, studied using synchrotron X-ray powder diffraction and 57Fe Mössbauer spectroscopy
- Partitioning of Sr, Ba, Rb, Y, and LREE between plagioclase and peraluminous silicic magma
- Infrared and TEM characterization of amphiboles synthesized near the tremolite-pargasite join in the ternary system tremolite-pargasite-cummingtonite
- Coupling between non-convergent ordering and transition temperature in the C2/c ↔ P21/c phase transition in pigeonite
- 57Fe Mössbauer-effect studies of Ca-rich, Fe-bearing clinopyroxenes: Part I. Paramagnetic spectra of magnesian hedenbergite
- 57Fe Mössbauer-effect studies of Ca-rich, Fe-bearing clinopyroxenes: Part II. Magnetic spectra of magnesian hedenbergite
- 57Fe Mössbauer-effect studies of Ca-rich, Fe-bearing clinopyroxenes: Part III. Diopside
- Letters. Aluminum substitution in MgSiO3 perovskite: Investigation of multiple mechanisms by 27Al NMR
- Studtite, [(UO2)(O2)(H2O)2](H2O)2: The first structure of a peroxide mineral
- Nanometer-scale measurements of iron oxidation states of cronstedtite from primitive meteorites