The Lamont—Doherty Geological Observatory Isolab 54 isotope ratio mass spectrometer

England, Jonathan; Zindler, Alan; Reisberg, Laurie; Rubenstone, J.L.; Salters, Vincent J. M.; Marcantonio, Franco; Bourdon, Bernard; Brueckner, Hannes K.; Turner, Patricia; Weaver, Susanna L. Widicus; Read, P.M.

doi:10.1016/0168-1176(92)80063-7

Cited by 31 publications

(7 citation statements)

References 15 publications

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“…Internal precision of the individual analyses is a factor of two better than the external precision. Some of the Samoan samples were analyzed for Hf isotopes using the Lamont Isolab [England et al, 1992] using separation technique and measurement protocol described by Salters [1994]. The Ko'olau samples were treated similarly to the MORB powders and were analyzed on the NEPTUNE MC-ICP-MS. [14] Methods used at the Max-Planck-Institut were as follows.…”

Section: Samples and Methodsmentioning

confidence: 99%

Domains of depleted mantle: New evidence from hafnium and neodymium isotopes

Salters

Mallick

Hart

et al. 2011

Geochem. Geophys. Geosyst.

114

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[1] Isotope systematics of basalts provide information on the distribution of mantle components and the length scale of mantle heterogeneity. To obtain this information, high data and sampling density are crucial. We present hafnium and neodymium isotope data on more than 400 oceanic volcanics. Over length scales of several hundred to over one thousand kilometers hafnium and neodymium isotopes of mid-ocean ridge basalts are correlated and form an array of parallel trends on a global scale. On a larger scale these domains differ in the amount of highly depleted mantle material with radiogenic hafnium and neodymium isotope ratios. Compared to the Atlantic and Indian Ocean basins the asthenosphere of the Pacific basin seems to have a more uniform and a less radiogenic Hf isotopic composition for a given Nd isotopic composition. The parallel arrays of mid-ocean ridge basalts provide strong constraints on the makeup of the MORB mantle and are evidence for the presence of a highly depleted and highly radiogenic neodymium and hafnium component. This component, because of its highly depleted character, is unrecognized in the strontium-neodymium-lead isotope systems alone. Alternatively, the parallel arrays can have an ancient origin of systematic variations in the degree of depletion. Each array then represents the variations in this fossil melting regime. Individual ocean island basalt suites display different slopes in hafnium-neodymium isotope space, which are also best explained by varying amounts of highly residual mantle rather than isotopic differences in enriched mantle components as previously invoked. The ocean island basalt arrays diverge at

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Section: Samples and Methodsmentioning

confidence: 99%

Domains of depleted mantle: New evidence from hafnium and neodymium isotopes

Salters

Mallick

Hart

et al. 2011

Geochem. Geophys. Geosyst.

114

View full text Add to dashboard Cite

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“…Ionisation of Th was drastically increased with ion sputtering to generate Th ions in a secondary ion mass spectrometer (SIMS), able to achieve figures > 2% for ionisation efficiency, although this was partly impaired by molecular and cluster interferences produced during sputtering, that required high mass resolution and/or energy filtering (England et al . ). Nevertheless, the SIMS approach enabled Th isotope amount ratios to be measured with an overall intermediate precision of 0.6% (2 RSD) on sample sizes ranging from 100 to 5 ng (England et al .…”

Section: Introductionmentioning

confidence: 97%

New Thorium Isotope Ratio Measurements in Silicate Reference Materials: A‐THO, AGV‐2, BCR‐2, BE‐N, BHVO‐2 and BIR‐1

Carpentier

Gannoun

et al. 2015

Geostandard Geoanalytic Res

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“…Hafnium isotopic measurements for 20 of 27 samples reported in Table 2 were carried out at NHMFL by HOT-SIMS techniques [Bizimis et al, 2003;Salters and Zindler, 1995] on the Lamont ISOLAB [England et al, 1992]. External reproducibility over a 2-year period was measured by repeat runs on JMC-475, with 176 Hf/ 177 Hf = 0.282200 ± 31 (2σ, n=44) [Bizimis et al, 2003].…”

Section: Measurement Techniquesmentioning

confidence: 99%

The influence of ridge geometry at the ultraslow-spreading Southwest Indian Ridge (9º-25ºE) : basalt composition sensitivity to variations in source and process

Standish¹

2006

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Between 9º-25º E on the ultraslow-spreading Southwest Indian Ridge lie two sharply contrasting supersegments. One 630 km long supersegment erupts N-MORB that is progressively enriched in incompatible element concentrations from east to west. The second 400 km long supersegment contains three separate volcanic centers erupting E-MORB and connected by long amagmatic accretionary segments, where mantle is emplaced directly to the seafloor with only scattered N-MORB and E-MORB erupted. Rather than a major break in mantle composition at the discontinuity between the supersegments, this sharp contrast in geometry, physiography, and chemistry reflects "source" versus "process" dominated generation of basalt.Robust along-axis correlation of ridge characteristics (i.e. morphology, upwelling rate, lithospheric thickness), basalt chemistry, and crustal thickness (estimated from gravity) provides a unique opportunity to compare the influence of spreading geometry and rate on MORB generation. What had not been well established until now is the importance of melting processes rather than source at spreading rates < 20 mm/yr. Along the orthogonally spreading supersegment (14 mm/yr) moderate degrees of partial melting effectively sample the bulk mantle source, while on the obliquely spreading supersegment (7-14 mm/yr) suppression of mantle melting to low degrees means that the bulk source is not uniformly sampled, and thus "process" rather than "source" dominates melt chemistry. AcknowledgementsThere are so many people to thank when reaching a milestone such as this, so let me start with those that have had the most recent impact on this accomplishment, my thesis committee; Henry Dick, Stan Hart, Ken Sims, Fred Frey, Anton le Roex, Mark Kurz, Jian Lin, and my thesis defense chairperson, Hans Schouten. With both Hans and Jian I have gained a new appreciation for and understanding of real-time seagoing geophysics, and I think all four of us (including Henry) have witnessed some pretty amazing human efforts and as a result grown together as people and scientists during the many days bouncing around the South Atlantic. Mark's analytical expertise, continuing support and encouraging words, and attention to detail, has kept my path over the last 6 years straight and narrow, and in the right direction. Anton has been a great source of information both regarding trace elements and more importantly the SW Indian Ridge. As one of the first geochemists to study the South Atlantic spreading ridges in detail, his early work through the 80's and 90's set the bar (and quite a high bar it was) for which all of my work will be gauged. It is a shame that our schedules did not coincide so that he could be here at WHOI for the defense, but I know much discussion will come from my work. Learning trace element geochemistry from Fred Frey was special. Fred's ability to get back to the basics and stress the importance to understanding "why" in the most fundamental terms is important in geochemistry. I very much appreciated his willingness to ...

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The Lamont—Doherty Geological Observatory Isolab 54 isotope ratio mass spectrometer

Cited by 31 publications

References 15 publications

Domains of depleted mantle: New evidence from hafnium and neodymium isotopes

Domains of depleted mantle: New evidence from hafnium and neodymium isotopes

New Thorium Isotope Ratio Measurements in Silicate Reference Materials: A‐THO, AGV‐2, BCR‐2, BE‐N, BHVO‐2 and BIR‐1

The influence of ridge geometry at the ultraslow-spreading Southwest Indian Ridge (9º-25ºE) : basalt composition sensitivity to variations in source and process

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