Poster Number 306
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See more from this Session: Sigma Gamma Epsilon Undergraduate Research (Posters)
Abstract:
Minna Saddle nunatak deposits include palagonitized planar and cross-bedded units, as well as fine-grained layers rich in accretionary and armored lapilli. The majority of the deposits are poorly sorted, and include both dense gray lava lithic clasts and juvenile bombs. The bedding and sedimentary structures are consistent with a phreatomagmatic origin. Deformation on a variety of scales, including faults with 1 to 30 m of offset, affects much of the outcrop. Muddy damage zones along fault planes and soft sediment deformation of the surrounding deposits suggest that the deposit was still wet when faulting occurred. Large spoon-shaped deposits are interpreted as slump blocks of water-saturated material. The characteristics of the deposits and the deformation suggest that water had a significant impact on eruptive and depositional processes during and after the eruption.
The interpretation of an explosive phreatomagmatic eruption is consistent with limited syneruptive ice cover, which provided meltwater to energize the eruption but did not submerge the volcano. The nunatak is heavily eroded and overlain by late Pleistocene erratic boulders. Ongoing research focuses on petrographic documentation of volcaniclastic lithofacies, chemical characterization of the nunatak rocks, and 40Ar/39Ar dating of the volcanic sequence.
See more from this Division: Topical Sessions
See more from this Session: Sigma Gamma Epsilon Undergraduate Research (Posters)