The application of laser ablation-inductively coupled plasma-mass spectrometry to in situ U–Pb zircon geochronology

Zircon is the main mineral in the majority of igneous and metamorphic rocks with Zr as an essential structural constituent. It is a host for significant fractions of the whole-rock abundance of U, Th, Hf, and the REE (Sawka 1988, Bea 1996, O’Hara et al. 2001). These elements are important geochemically as process indicators or parent isotopes for age determination. The importance of zircon in crustal evolution studies is underscored by its predominant use in U-Th-Pb geochronology and investigations of the temporal evolution of both the crust and lithospheric mantle. In the past decade an increasing interest in the composition of zircon, trace-elements in particular, has been motivated by the effort to better constrain in situ microprobe-acquired isotopic ages. Electron-beam compositional imaging and isotope-ratio measurement by in situ beam techniques—and the micrometer-scale spatial resolution that is possible—has revealed in many cases that single zircon crystals contain a record of multiple geologic events. Such events can either be zircon-consuming, alteration, or zircon-forming and may be separated in time by millions or billions of years. In many cases, calculated zircon isotopic ages do not coincide with ages of geologic events determined from other minerals or from whole-rock analysis. To interpret the geologic validity and significance of multiple ages, and ages unsupported by independent analysis of other isotopic systems, has been the impetus for most past investigations of zircon composition. Some recent compositional investigations of zircon have not been directly related to geochronology, but to the ability of zircon to influence or record petrogenetic processes in igneous and metamorphic systems.

Sedimentary rocks may also contain a significant fraction of zircon. Although authigenic zircon has been reported (Saxena 1966, Baruah et al. 1995, Hower et al. 1999), it appears to be very rare and may in fact be related to …

/pdf/the-composition-of-zircon-and-igneous-and-metamorphic-1g2xfkpi4l.pdf

The Composition of Zircon and Igneous and Metamorphic Petrogenesis

Plesovice zircon : A new natural reference material for U-Pb and Hf isotopic microanalysis

In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard

Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2 emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2 conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions.

/pdf/ocean-acidification-the-other-co-2-problem-4h18mw2cpj.pdf

Ocean Acidification: The Other CO 2 Problem

Enriched fecal and urine samples were prepared using ion-exchange column chromatography for analysis by Inductively Coupled and Fast Atom Bombardment Mass spectrometry (ICP-MS, FAB-MS) to compare precision between methods. Unenriched samples of human milk, feces, and whole blood were prepared similarly to monitor instrumental precision and analytical error. A least squares fit of the ICP-MS results vs the FAB-MS for70Zn/64Zn gave a slope of 0.98, with a relative standard deviation (RSD) of only 0.7%. The results for68Zn/64Zn gave a slope of 0.82, with a RSD of 14%. For unenriched tissues, all potential interferences were removed by the preparation procedure with no significant differences between preparation for isotope ratios of70Zn/64Zn,68Zn/64Zn,67Zn/64Zn, and66Zn/64Zn. Poisson counting statistics are a major contribution to the total analytical error indicating the usefulness of this procedure for enrichment studies.

Determination of isotope ratios in human tissues enriched with zinc stable isotope tracers using inductively coupled plasma-mass spectrometry (ICP-MS).

The Ni–Cr–Cu content of biotite as pathfinder elements for magmatic sulfide exploration associated with mafic units of the Sudbury Igneous Complex, Ontario, Canada

Quantitative elemental mapping of granulite‐facies monazite: Textural insights and implications for petrochronology

Geological controls on the stable tellurium isotope variation in tellurides and native tellurium from epithermal and orogenic gold deposits: Application to the Emperor gold-telluride deposit, Fiji

Analysis of the drinking water of mothers of neural tube defect infants and of normal infants for 14 selected trace elements by inductively coupled plasma-mass spectrometry (ICP-MS)

Simon E. Jackson

Papers

Determination of isotope ratios in human tissues enriched with zinc stable isotope tracers using inductively coupled plasma-mass spectrometry (ICP-MS).

The Ni–Cr–Cu content of biotite as pathfinder elements for magmatic sulfide exploration associated with mafic units of the Sudbury Igneous Complex, Ontario, Canada

Quantitative elemental mapping of granulite‐facies monazite: Textural insights and implications for petrochronology

Geological controls on the stable tellurium isotope variation in tellurides and native tellurium from epithermal and orogenic gold deposits: Application to the Emperor gold-telluride deposit, Fiji

Analysis of the drinking water of mothers of neural tube defect infants and of normal infants for 14 selected trace elements by inductively coupled plasma-mass spectrometry (ICP-MS)