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A deep high‐resolution optical log of dust, ash, and stratigraphy in South Pole glacial ice
Author(s) -
Bramall N. E.,
Bay R. C.,
Woschnagg K.,
Rohde R. A.,
Price P. B.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl024236
Subject(s) - geology , volcanic ash , volcano , borehole , stratigraphy , layering , explosive eruption , mineralogy , glacial period , geomorphology , geochemistry , magma , paleontology , botany , biology , tectonics
We describe a new dust logger designed to operate in water‐filled IceCube boreholes in South Pole ice, and we give examples of its performance. We recorded optical effects due to bubbles, dust, and volcanic ash in situ from ∼70 to 2100 meters. Seasonal layering in bubble concentration could also be discerned. Below ∼1300 m over the interval 25 ka to 70 ka, because of the conversion of all air bubbles to invisible hydrate crystals, and the close match between refractive indices of the surrounding ice and the water in the borehole, scattering from dust provided fine‐structure in the depth‐dependence of concentration with a resolution of <1 cm. Thin, highly absorptive horizons in the data set confirm there is significant fallout at South Pole of ash from explosive volcanic events. By locating and dating volcanic ash layers in the South Pole dust record, it may be possible to match them to volcanic layers found across Antarctica and in Greenland.