NBP14-02: The Sabrina Coast Marine Record of Ocean-Cryosphere Dynamics

Abstract:

In January 2014, an international research team embarked on a multidisciplinary ship-based expedition (NBP14-02) to the Totten Glacier/Moscow University Ice Shelf (TG/MUIS) area on the Sabrina Coast, East Antarctica. This system marks the termination of the largest marine-based portion of the East Antarctic Ice Sheet (EAIS; ~7 m sea level potential), yet little is known about its stability. Recent satellite data indicate regional ice thinning of TG/MUIS, possibly related to ocean-induced basal melt. However, the adjacent continental shelf was not comprehensively surveyed before NBP14-02 due to its remoteness and predominant sea ice cover.

NBP14-02 scientists conducted physical-chemical, geophysical, and geological surveys of this practically unexplored region to evaluate recent and longer-term ocean-cryosphere linkages. Hydrographic measurements revealed southward transport of relatively warm subsurface waters from near the shelf break to the mid-shelf that weakened farther south near the ice shelf edge, contrary to initial hypotheses. Swath bathymetry mapped many glacial features, suggesting a complex regional glacial and deglacial history. We identified a network of channels scoured into bedrock that were spatially associated with glacial geoforms and may have formed during large subglacial meltwater outbursts. Over 750 km of high-resolution multichannel seismic data were acquired. Seismic profiles revealed the region’s geologic and climatologic history since the onset of Antarctic-Australian rifting, including evidence for: 1. fluvial deltaic systems, 2. intermittent glaciations, 3. the onset of persistent glaciation and significant ice loading, and 4. more recent glacial advance and retreat cycles. Coring and dredging operations, guided by geophysical data, enabled the collection of older sediments from outcropping unconformities and expanded Holocene sequences from restricted basins.

 The multidisciplinary nature of NBP14-02 enabled a rapid, but detailed, baseline assessment of a previously unexplored area. This approach was useful for introducing students to a broad range of oceanographic techniques and ideal for research expeditions subject to the unpredictable nature of the short Antarctic field season.