TEXTURAL AND MICROANALYSIS OF IGNEOUS ROCKS: TOOLS ...

flow [33]. I selected a single sample from the Unit 10 flow with minimal alteration
(183-1137A-46R-01W-20-35; Fig. 4.2).
4.3 Analytical Techniques
4.3.1 Sample Preparation
Basalt samples were prepared as polished thin sections using a microdiamond
slurry and final grit size of 0.5 µm. Prior to analytical work the slides were rinsed
in ethanol in an ultrasonic bath to remove remnants of the polishing compounds
followed by three 30 minute rinses in ultrapure water in an ultrasonic bath. Sam-
ples were carbon coated for EPMA work. After completion of EPMA work the
carbon coats were removed with 3 µm and 1 µm diamond polishing clothes under
ethanol followed by three 30 minutes rinses in ultrapure water in an ultrasonic
bath. The surface of each slide was inspected under a reflected light optical mi-
croscope to confirm that all vestiges of the carbon coat had been removed prior to
LA-ICP-MS work. Slides were re-polished and re-cleaned after LA-ICP-MS and
prior to Sr isotope microdrilling.
4.3.2 Electron Probe Microanalysis (EPMA) and Scanning Electron Microscopy
Backscatter electron images and major element analyses were performed us-
ing a JEOL JXA-8600 Superprobe electron microprobe at the University of Notre
Dame. Backscatter electron images were collected using a 1 µm beam, an acceler-
ating voltage of 20 kV, and a probe current of 25-50 nA. Microprobe analyses were
performed using a 10 µm defocused beam, accelerating voltage of 15 kV, a probe
current of 20 nA, 15 second on-peak counting time, and two background measure-
ments per peak. Sodium was measured first to minimize loss via volatilization.
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