Origin, structure and geochemistry of a rock glacier near Don Juan Pond, Wright Valley, Antarctica

Abstract

The South Fork of Wright Valley contains one of the largest rock glaciers in the McMurdo Dry Valleys, Antarctica, stretching 7 km from the eastern boundary of the Labyrinth and terminating at Don Juan Pond (DJP). Here, we use results from ground-penetrating radar (GPR), qualitative field observations, soil leaching analyses and X-ray diffraction analyses to investigate rock glacier development. The absence of significant clean ice in GPR data, paired with observations of talus and interstitial ice influx from the valley walls, support rock glacier formation via talus accumulation. A quartz-dominated subsurface composition and discontinuous, well-developed desert pavements suggest initial rock glacier formation occurred before the late Quaternary. Major ion data from soil leaching analyses show higher salt concentrations in the rock glacier and talus samples that are close to hypersaline DJP. These observations suggest that DJP acts as a local salt source to the rock glacier, as well as the surrounding talus slopes that host water track systems that deliver solutes back into the lake, suggesting a local feedback system. Finally, the lack of lacustrine sedimentation on the rock glacier is inconsistent with the advance of a glacially dammed lake into South Fork during the Last Glacial Maximum.

Rock Glacier Characteristics Under Semiarid Climate Conditions in the Western Nyainqêntanglha Range, Tibetan Plateau

“…This information is crucial for a discussion and understanding of the role of rock glaciers in the context of climate warming and water storage capacities. To assess the internal structure of a rock glacier, several geophysical methods should be applied in combination with geomorphological and geological assessments of the surrounding headwalls and rock materials (Farbrot et al., 2005; Ikeda, 2006; Kellerer‐Pirklbauer & Kaufmann, 2018; Maurer & Hauck, 2007; Winsor et al., 2020). A recent study employed environmental seismology to assess spatial and short‐term activity patterns of a single rock glacier (Guillemot et al., 2020).…”

“…Generally, the characteristics and development of rock glaciers are driven by lithology (e.g., Ikeda & Matsuoka, 2006;Matsuoka & Ikeda, 2001) and climate conditions (e.g., Monnier & Kinnard, 2017;Washburn, 1980) and are therefore controlled by the availability of water, ice and also, rock debris (Barsch, 1996;Knight et al, 2019). In addition to the initial setting controlling rock glacier formation (Bolch & Gorbunov, 2014;Kellerer-Pirklbauer & Kaufmann, 2018;Winsor et al, 2020), concepts of its evolution pathways have also be proposed: Anderson et al (2018) modeled a continuous pathway by using different states of the equilibrium line altitude (ELA) to describe the evolution of a glacier into a debris covered glacier and finally into a rock glacier as an endmember. The increase of debris amount in this continuum delayed the response of the debris-covered glaciers of melting to climate warming (Collier et al, 2015) and its evolution into the endmember "rock glacier" (Anderson et al, 2018).…”