Faculty candidate seminar - Lauren Simkins

04/24/2017 - 4:00pm
Hubbs Hall 4500
Event Description: 


DATE:          April 24th, Monday, 4:00pm  

LOCATION:     Hubbs Hall 4500
SPEAKER:      Lauren Simkins, Ph.D.
                        Rice University 
TITLE:          Grounding line dynamics of the Antarctic Ice Sheet: What can we learn from the geological record? 

Marine-based ice sheets are vulnerable portions of the cryosphere and have the potential to contribute to future rapid sea-level rise, yet model projections of ice mass balance have large uncertainties. The stability of marine-based ice sheets is largely dictated by perturbations at or near the grounding line, the downstream most location grounded ice is in contact with the underlying bed, where marine and glacial processes the converge; however, observational constraints from modern grounding lines are limited. The geological record from deglaciated continental margins extends the spatial and temporal perspectives on grounding line processes and behavior, particularly on longer timescales that are not captured in modern oceanographic and satellite-era observations. Based on geophysical and sedimentological data from the Ross Sea, Antarctica, I will discuss two studies focused on (1) subglacial meltwater delivery to former grounding lines and (2) a landform-based approach to controls on grounding line stability (and instability). The discovery of a 150-kilometer long sediment-based subglacial meltwater channel indicates repeated meltwater delivery to a retreating grounding line of the East Antarctic Ice Sheet at a frequency of decades to centuries following the Last Glacial Maximum. Furthermore, a dataset of more than 6,250 ice-marginal landforms demonstrates that landform morphology is strongly controlled by sediment flux to the grounding line, which varies considerably across a single paleo-grounding line. The spatial distribution of landforms shows that bed topography has a minimal control on both morphology and grounding line retreat patterns. These paleo-insights highlight the importance of understanding channelized meltwater drainage and the growth of ice-marginal landforms to assess the stability of former and contemporary marine-based ice sheet grounding lines. 
Faculty Host:  Adrian Borsa  (aborsa@ucsd.edu)
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