Summary
The presence and nature of marine ice in ice shelves is important, yet difficult to determine. We present transient electromagnetic results spanning 10 km across a suture zone of Larsen C Ice Shelf (LCIS), Antarctica, supported by central borehole measurements. Our results indicate the presence of two ice-shelf layers. The uppermost layer, ∼300 m thick, has resistivity 103−106 Ωm. We interpret this as meteoric ice, overlying a lower shelf layer 25–56 m thick with resistivity 3–20 Ωm, consistent with permeable basal marine ice. This reconstruction closely matches modeled marine-ice thicknesses in the area. The porosity of this layer is 0.18–0.40, higher than measured farther down-flow, suggesting the layer consolidates once formed. Within the upper layer at 78.5 m depth, we identify a 2.5 m thick layer, likely linked to brine infiltration. These heterogeneities in ice shelf properties should be accounted for in future LCIS stability assessments.