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Mudstone--the most abundant sedimentary rock type, composed primarily of clay- or silt-sized particles--contains most of the quartz found in sedimentary rocks. These quartz grains, which are chemically and mechanically resistant and therefore preserve their characteristics well, have long been considered to be derived from the continental crust. Here we(More)
Observations of martian surface morphology have been used to argue that an ancient ocean once existed on Mars. It has been thought that significant quantities of such water could have been supplied to the martian surface through volcanic outgassing, but this suggestion is contradicted by the low magmatic water content that is generally inferred from(More)
A method has been developed and used on-line with inductively couple plasma mass spectrometry for the rapid separation and concentration of uranium prior to elemental and isotopic analysis. This methodology is termed electrochemically-modulated separation (EMS) and relies on the ability to change the analyte retention of a surface by changing (i.e.,(More)
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