PowerPoint Presentation

Trace metal analysis in carbonates using theCameca NanoSIMSJohn EilerSharp Professor of Geology and GeochemistryDirector, Caltech Microanalysis CenterCalifornia Institute of Technology

With contributions fromJess Adkins, Anne Dekas, Rinat Gabitov, Alex Gagnon, Amy Hofmann and Katie SnellWisc SIMS Paleoclimate WorkshopJune 25th, 20131

Mitsuguchi et al., 1996CaCO3 + Mgaq = MgCO3 + CaaqKeq MgCaCaMg[ ]min[ ]fluidx

Cation-exchange paleothermometry

Stanley and Hardie, 1998; model of Hardie, 1996Global budgetsWeatheringHydrothermalSedimentsAlteration

Eggins et al., 2004; Hitch #1: Vital effectsGagnon et al., 2007ForaminiferaDeep-sea coral

Allison et al., 2007Hitch #2: DiagenesisPA: Primary Aragonite; SA: Secondary Aragonite; SC: Secondary CalciteCements vs. PrimaryThe Cameca NanoSIMS

6Geometry of focusing and extraction lensesWhat puts the nano in nanoSIMS Short working distance promotes small, dense probe Extraction optics easily contaminated or damaged

7Minimum spot size Nominally 50 nm for Cs+, 150 nm for O- (84/16 % definition) Actual minimum ca. 20 nm for Cs+, ca. 100 nm for O- Brighter beams needed for trace element mapping typically in 100-300 nm range Actually tricky to measure in many samples; assume it is ~500 nm unless proven otherwise

1 mSi metal in Al matrix