D. Cherniak - Academia.edu (original) (raw)

Papers by D. Cherniak

Oxygen diffusion in natural and synthetic single-crystal titanite was characterized under both dr... more Oxygen diffusion in natural and synthetic single-crystal titanite was characterized under both dry and water-present conditions. For the dry experiments, pre-polished titanite samples were packed in 18 O-enriched quartz powder inside Ag-Pd capsules, along with a fayalite-magnetite-quartz (FMQ) buffer assemblage maintained physically separate by Ag-Pd strips. The sealed Ag-Pd capsules were themselves sealed inside evacuated silica glass tubes and run at 700-1050°C and atmospheric pressure for durations ranging from 1 h to several weeks. The hydrothermal experiments were conducted by encapsulating polished titanite crystals with 18 O enriched water and running at 700-900°C and 10-160 MPa in standard cold-seal pressure vessels for durations of 1 day to several weeks. Diffusive uptake profiles of 18 O were measured in all cases by nuclear reaction analysis (NRA) using the 18 O (p,α) 15 N reaction.

The geochemistry of argon has proven important in geochronology and for the development of models... more The geochemistry of argon has proven important in geochronology and for the development of models for terrestrial accretion, mantle structure, outgassing and atmosphere formation. In order to develop models of geochemical processes using noble gases, their diffusivities and solubilities must be known. Many studies during the last several decades have increased our understanding of noble gas diffusion and solubility in

Earth and Planetary Science Letters, 2003

Silicon diffusion was measured in natural quartz and anorthitic feldspar under dry, low-pressure ... more Silicon diffusion was measured in natural quartz and anorthitic feldspar under dry, low-pressure (0.1 MPa) conditions using a 30Si tracer. Sources of diffusant consisted of 30Si-enriched silica powder for experiments on quartz and microcrystalline 30Si-doped synthetic feldspar of composition comparable to the feldspar specimens. Distributions of 30Si were measured with Rutherford backscattering spectrometry and nuclear reaction analysis, using the reaction

Reviews in Mineralogy and Geochemistry, 2010

... minerals, including zircon (Cherniak et al. 1997a,b) and the feldspars (eg, Giletti and Shana... more ... minerals, including zircon (Cherniak et al. 1997a,b) and the feldspars (eg, Giletti and Shanahan 1994; Giletti and Casserly 1994; Cherniak and Watson 1992, 1994; Cherniak 2003; Foland 1974). Interestingly Sr, Pb, and REE ...

Physics and Chemistry of Minerals, 1998

Diffusion of four rare-earth elements and gallium has been measured in yttrium aluminum garnet (Y... more Diffusion of four rare-earth elements and gallium has been measured in yttrium aluminum garnet (YAG). Sources of diffusant were mixtures of alumina and rare-earth element oxides for REE diffusion, and mixtures of gallium and yttrium oxides for Ga diffusion. Diffusion profiles were measured with Rutherford backscattering spectrometry (RBS). For the rare-earth elements investigated, the following Arrhenius relations were obtained:

Geochimica et Cosmochimica Acta, 2007

Like most other minerals, titanite rarely if ever forms perfect crystals. In addition to the poin... more Like most other minerals, titanite rarely if ever forms perfect crystals. In addition to the point defects that might affect lattice diffusion, there may be extended line-or planar defects along which fast diffusion could occur. During the course of an experimental study of oxygen lattice diffusion in titanite, we found that almost all of the 18 O uptake profiles produced in natural titanite crystals departed from the complementary error function solution expected for simple lattice diffusion with a constant surface concentration. Instead, they exhibited ''tails'' extending deeper into the samples than expected for simple lattice diffusion. The purpose of this contribution is to report on these features-described as ''fast-paths'' for oxygen diffusion-and outline a method for coping with them in extracting information from diffusion profiles. For both dry and hydrothermal experiments in which the ''fast paths'' are observed, 18 O was used as the diffusant. In dry experiments, the source material was 18 O-enriched SiO 2 powder, while 18 O-enriched water was used for the hydrothermal experiments. Diffusive uptake profiles of 18 O were measured in all cases by nuclear reaction analysis (NRA) using the 18 O (p,a) 15 N reaction [see Zhang X. Y., Cherniak D. J., and Watson E. B. (2006) Oxygen diffusion in titanite: lattice and fast-path diffusion in single crystals. Chem. Geol. 235 105-123].

Geochimica et Cosmochimica Acta, 2002

Diffusion of Ba in natural sanidine and plagioclase has been characterized under dry 1 atm condit... more Diffusion of Ba in natural sanidine and plagioclase has been characterized under dry 1 atm conditions. Polished or cleaved sections of the feldspars were surrounded by source powders in Pt capsules and annealed in air. Sources of diffusant consisted of BaO, SiO 2 and Al 2 O 3 powders mixed with ground feldspar and prereacted in Pt crucibles at 975°C. Prepared sample capsules were annealed for times ranging from 1 h to a few months at temperatures from 775 to 1124°C. The Ba distributions in the feldspars were profiled by Rutherford Backscattering Spectrometry (RBS).

Geochimica et Cosmochimica Acta, 2012

The diffusive closure temperature of minerals (T C ) was originally conceived for application to ... more The diffusive closure temperature of minerals (T C ) was originally conceived for application to systems undergoing cooling and is of limited use for cases of diffusive "opening" during heating or for complete heating-cooling cycles. Here we use a combination of numerical simulations and mathematics to arrive at general equations for progressive diffusive loss from a sphere when temperature increases linearly with time, and also for discrete thermal pulses. For linear heating (T ∝ time), and with constant surface concentration and no radiogenic in-growth, prograde "diffusive opening" is accurately described by

Geochimica et Cosmochimica Acta, 1996

Strontium chemical diffusion has been measured in albite and sanidine under dry, 1 atm, and QFM b... more Strontium chemical diffusion has been measured in albite and sanidine under dry, 1 atm, and QFM buffered conditions. Strontium oxide-aluminosilicate powdered sources were used to introduce the diffusant and Rutherford Backscattering Spectroscopy (RBS) used to measure diffusion profiles. For the 1 atm experiments, the following Arrhenius relations were obtained: Sanidine (Or61), temperature range 725–1075°C, diffusion normal to (001): D=8.4 exp(−450±13

Earth and Planetary Science Letters, 1997

in natural, non-metamict zircon was characterized under both dry and water-present conditions at ... more in natural, non-metamict zircon was characterized under both dry and water-present conditions at temperatures ranging from 765°C to 1500°C. Dry experiments were performed at atmospheric pressure by encapsulating polished zircon samples with a fine powder of "O-enriched quartz and annealing the sealed capsules in air. Hydrothermal runs were conducted in cold-seal pressure vessels (7-70 MPa) or a piston cylinder apparatus (400-1000 MPa) on zircon samples encapsulated with both "O-enriched quartz and "0 water. Diffusive-uptake profiles of 'so were measured in all samples with a particle accelerator, using the "O( p, (Y )15N reaction. For dry experimental conditions at 11 OO-1500°C the resulting oxygen diffusivities (24 in all) are well described by:

Earth and Planetary Science Letters, 1992

Sr chemical diffusion has been measured in orthoclase, anorthoclase and anorthite under dry, 1-at... more Sr chemical diffusion has been measured in orthoclase, anorthoclase and anorthite under dry, 1-atm conditions. A strontium oxide-aluminosilicate powder mixture was used as the source material, with Rutherford Backscattering Spectroscopy (RBS) used to measure diffusion profiles. Over the temperature range 725-1075°C the following Arrhenius relations were obtained.

Earth and Planetary Science Letters, 2004

We report measurements of oxygen diffusion in natural monazites under both dry, 1-atm conditions ... more We report measurements of oxygen diffusion in natural monazites under both dry, 1-atm conditions and hydrothermal conditions. For dry experiments, 18 O-enriched CePO 4 powder and monazite crystals were sealed in Ag-Pd capsules with a solid buffer (to buffer at NNO) and annealed in 1-atm furnaces. Hydrothermal runs were conducted in cold-seal pressure vessels, where monazite grains were encapsulated with 18 O-enriched water. Following the diffusion anneals, oxygen concentration profiles were measured with Nuclear Reaction Analysis (NRA) using the reaction 18 O(p,a) 15 N. Over the temperature range 850-1100 8C, the Arrhenius relation determined for dry diffusion experiments on monazite is given by:

Contributions to Mineralogy and Petrology, 2000

... 1981; Hoshino et al. 1985). Cation vacancies are a minority defect, produced by the formation... more ... 1981; Hoshino et al. 1985). Cation vacancies are a minority defect, produced by the formation of Frenkel or Schottky defects. If alt-ervalent impurities reside on Ti sites in rutile, there are additional point defects, MeTi′′, MeTi′, and MeTi . for ...

Contributions to Mineralogy and Petrology, 2006

Chemical diffusion of Zr under anhydrous, pO2-buffered conditions has been measured in natural ti... more Chemical diffusion of Zr under anhydrous, pO2-buffered conditions has been measured in natural titanite. The source of diffusant was either zircon powder or a ZrO2–Al2O3–titanite mixture. Experiments were run in sealed silica glass capsules with solid buffers (to buffer at NNO or QFM). Rutherford Backscattering Spectrometry (RBS) was used to measure diffusion profiles. The following Arrhenius parameters were obtained for

Contributions to Mineralogy and Petrology, 2010

Diffusion of Li under anhydrous conditions at 1 atm and under fluid-present elevated pressure (1.... more Diffusion of Li under anhydrous conditions at 1 atm and under fluid-present elevated pressure (1.0-1.2 GPa) conditions has been measured in natural zircon. The source of diffusant for 1-atm experiments was ground natural spodumene, which was sealed under vacuum in silica glass capsules with polished slabs of zircon. An experiment using a Dy-bearing source was also conducted to evaluate possible rate-limiting effects on Li diffusion of slow-diffusing REE ?3 that might provide charge balance. Diffusion experiments performed in the presence of H 2 O-CO 2 fluid were run in a piston-cylinder apparatus, using a source consisting of a powdered mixture of spodumene, quartz and zircon with oxalic acid added to produce H 2 O-CO 2 fluid. Nuclear reaction analysis (NRA) with the resonant nuclear reaction 7 Li(p,c) 8 Be was used to measure diffusion profiles for the experiments. The following Arrhenius parameters were obtained for Li diffusion normal to the c-axis over the temperature range 703-1.151°C at 1 atm for experiments run with the spodumene source: D Li ¼ 7:17 Â 10 À7 expðÀ275 AE 11 kJmol À1 =RTÞm 2 s À1 :

Contributions to Mineralogy and Petrology, 1997

Diusion rates for the three tetravalent cations U, Th and Hf have been measured in synthetic zirc... more Diusion rates for the three tetravalent cations U, Th and Hf have been measured in synthetic zircon. Diusant sources included oxide powders and ground pre-synthesized silicates. Rutherford backscattering spectrometry (RBS) was used to measure depth pro®les. Over the temperature range 1400±1650°C, the following Arrhenius relations were obtained (diusion coecients in m 2 sec À1 ):

Contributions to Mineralogy and Petrology, 1995

Page 1. Contrib Mineral Petrol (1995) 120:358-371 9 Springer-Verlag 1995 DJ Cherniak Diffusion of... more Page 1. Contrib Mineral Petrol (1995) 120:358-371 9 Springer-Verlag 1995 DJ Cherniak Diffusion of lead in plagioclase and K-feldspar: an investigation using Rutherford Backscattering and Resonant Nuclear Reaction Analysis ...