Abstract
Sedimentary Ice Rafted Debris (IRD) provides critical information about
the climate sensitivity and dynamics of ice sheets. In recent decades,
high-resolution investigations have revelated ice rafting events in
response to rapid warming: such reconstructions help us constrain the
near-future stability of our planet‘s fast-changing cryosphere. However,
similar efforts require laborious and destructive analytical procedures
to separate and count IRD. Computed Tomography (CT) holds great promise
to overcome these impediments to progress by enabling the micrometer
scale visualization of individual IRD grains. This study demonstrates
the potential of this emerging approach by 1) validating CT counts in
synthetic sediment archives (phantoms) spiked with a known number of
grains, 2) replicating published IRD stratigraphies, and 3) improving
sampling resolution. Our results show that semi-automated CT counting of
grains in the common 150-500 µm size fraction reproduces actual particle
numbers and tracks manually counted trends. We also find that
differences between manual and CT-counted data are explained by image
processing artifacts, offsets in sampling resolution and bioturbation.
By acquiring these promising results using basic image processing tools,
we argue that our work advances and broadens the applicability of
ultra-high resolution IRD counting with CT to deepen our understanding
of ice sheet-climate interactions on human-relevant timescales.