Shipboard Characterization of Tuvalu, Samoa, and Lau Dredge Samples Using Laser-Induced Breakdown Spectroscopy (LIBS).

Chemical analysis using laser-induced breakdown spectroscopy (LIBS) is well suited for field applications and was applied here for shipboard characterization of a large sample set during the RR1310 rock dredging expedition to the Tuvalu Seamounts. Although recently the most common data treatment for LIBS has consisted of a partial least squares approach to define sample groupings, we show that quantitative data of useful quality can be obtained with a univariate approach. Here, our analysis goal was a quantitative comparison of the total alkali (NaO + KO) versus silica (SiO) contents of 586 representative dredge samples with known ranges in common rock types.

On the relative motions of long-lived Pacific mantle plumes.

Mantle plumes upwelling beneath moving tectonic plates generate age-progressive chains of volcanos (hotspot chains) used to reconstruct plate motion. However, these hotspots appear to move relative to each other, implying that plumes are not laterally fixed. The lack of age constraints on long-lived, coeval hotspot chains hinders attempts to reconstruct plate motion and quantify relative plume motions.

Primordial helium entrained by the hottest mantle plumes.

Helium isotopes provide an important tool for tracing early-Earth, primordial reservoirs that have survived in the planet's interior. Volcanic hotspot lavas, like those erupted at Hawaii and Iceland, can host rare, high He/He isotopic ratios (up to 50 times the present atmospheric ratio, Ra) compared to the lower He/He ratios identified in mid-ocean-ridge basalts that form by melting the upper mantle (about 8Ra; ref. 5).

A case of tracheobronchomegaly.

Tracheobronchomegaly (Mounier-Kuhn syndrome) is a rare condition characterized by an abnormally enlarged trachea and main bronchi. Herein, we present a case of 79-year-old male with idiopathic pulmonary fibrosis and acute hypoxemic respiratory failure due to multilobar pneumonia. Computed tomography of the chest demonstrated a markedly dilated trachea, with the transverse diameter of 31mm and the sagittal diameter of 30mm.

Magnesium isotopic homogeneity of San Carlos olivine: a potential standard for Mg isotopic analysis by multi-collector inductively coupled plasma mass spectrometry.

Rationale: Previous analyses on San Carlos olivine from Arizona (USA) have shown inter-laboratory δ(26) Mg differences of up to 0.67‰, while mantle olivine samples worldwide are homogeneous at a current analytical uncertainty of ~0.1‰.