As an addendum to glaciochemical interpretations resulting from our studies in the Indian Himalaya (Lyons and Reference Mayewski, Mayewski, Lyons and AhmadMayewski, 1983; Reference Mayewski, Mayewski, Lyons and AhmadMayewski and others, 1983, Reference Mayewski, Mayewski, Lyons, Ahmad, Smith and Pourchet1984), we present an account of Scanning Electron Microscope (SEM) and Energy Dispersive Atomic X-ray EDAX) analyses conducted on seven randomly distributed samples from our 16.6 m core from Nun Kun, Ladakh Himalaya (Reference Mayewski, Mayewski, Lyons, Ahmad, Smith and PourchetMayewski and others, 1984).
Approximately 16 ml was removed from each sample and filtered through a 20 cm2 Millipore T. M. filter system using 0.5 μm Millipore membrane filters. Each filter was then put in a covered petri dish and stored at 60° C for several days. Approximately 2 cm2 from each filter was mounted on aluminum viewing studs and coated with 0.2 nm of a gold and palladium combination. A total of 46 pictures and 37 EDAX scans were finally produced from the samples, from which four basic morphological groups are differentiated (platy, angular, biogenic, and anomalous). A description and interpretation by morphology follows:
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1. Platy (Fig. 1a) – characterized by length (range 13–160 μm) and width (range 13–83 μm) much greater than thickness, and “flaky” cleavage. A majority of the particles in this group had EDAX scans dominated by Si, Al, and K, and for some particles associated Fe and Mg in place of K. They probably consist of sheet silicates (clays) derived from crustal weathering. The size range of the particles would suggest a local source (Reference Mayewski, Mayewski, Lyons, Ahmad, Smith and PourchetMayewski and ohters, 1984).
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2. Angular (Fig. 1b) – characterized by length (range 9–296 μm), width (range 11–130 μm), and an apparently equal range in thickness with 90° or 60–120° cleavages. A majority of the particles had EDAX scans of Si, Al, and K with in some cases K. replaced by Ca and Mg. These particles are probably feldspars derived from a relatively local crustal weathering source (Reference Mayewski, Mayewski, Lyons, Ahmad, Smith and PourchetMayewski and others, 1984).
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3. Biogenic – characterized by a wide range in size from 7 μm to 140 μm in diameter. EDAX scans suggest a composition with few if any elements having atomic numbers greater than 10. By qualitative inspection, these particles comprise approximately 5% of the total number of particles observed in this study. Examples include diatoms (Fig. 1c) and pollen (Fig. 1d). These particles have potential for future study as both source indicators and as seasonal stratigraphic markers.
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4. Anomalous – characterized by a wide variety of size ranges and EDAX scans. This group is a composite of all particles that do not fit in other groups. They comprise approximately 15% of all particles viewed. Examples include a particle with a distinctly high Ca concentration (Fig. 1e) and one with a high Ti concentration (Fig. 1f). These particles have the potential for being useful in uniquely defining source areas.
Fig. 1. a. Example of platy group; 160 μm × 83 μm, × 337. b. Example of angular group; 9 μm × 11 μm. × 4235. c. Example of diatom; 8 μm × 90 μm. × 948. d. Example of pollen grain; 43μm × 52 μm, × 827 e. Example of anomalous group; Ca-rich, 7 μm × 11 μm. × 4554. f. Example of anomalous group; Ti-rich, 38 μm × 11 μm, × 1301.
Acknowledgements
This research was supported by U.S. National Science Foundation grant INT-80-03175. We greatly appreciate the assistance rendered by M.M. Ecker of the UNH Electron Microscope Facility.
