Aeolian processes and landforms at Mesrug on sub-Antarctic Marion Island

• Main Author: Nguna, Abuyiselwe Athandile
• Format: Master Thesis
• Language: English
• Published: University of Fort Hare 2019
• Subjects: Eolian processes Sediments (Geology); Antarctic; Antarc*; Marion Island
• Online Access: http://hdl.handle.net/10353/17095; https://corycommons.ru.ac.za/vital/access/manager/Repository/vital:40848

Recent observations have recognised the increasing role of aeolian processes as a geomorphic agent on sub-Antarctic Marion Island. This study presents the first long-term data on aeolian processes and dynamics at Mesrug (46° 56’ 41”S; 37° 49’ 59”E) on subAntarctic Marion Island. An intensive and high-resolution (five-minute interval) environmental monitoring campaign was initiated using Pace Scientific XR5 data loggers while aeolian transported sediments were collected using Big Spring Number Eight (BSNE) sediment traps at four different heights above the ground. The aeolian features at Mesrug is identified as mega-ripples and is essentially an erosional feature, while annual sediment flux at 0.05 m height were calculated as 2.29 kg cm-2 y -1 . Spatial data based on a two-year survey showed that the entire surface of the study area have lowered by deflation while the ripples shifted slightly eastward (down-wind). Furthermore, the site lost 3.4 m3 of sediment between these two surveys with an average of 0.75 cm per 1 m2 across the site which has an area of 454 m2 . The study suggest that the relatively large particle size of surface sediments on Marion Island is a major contributor to the low annual aeolian sediment flux. From the AWS data it is clear that high wind speeds are frequent at Mesrug and the high wind speeds facilitating sediment movement. Sediment supply is the limiting factor of aeolian sediment transport, but even though the perennial wetness experienced on the island is not a major limiting factor to sediment flux, it may influence rate of movement. The predominant wind direction at the study site is from the south-west but maximum wind velocities are from the north-west. The data from the wind-aspirated BSNE sediment traps, indicate that sediment movement occurs closest to the surface and weight of sediment moved as well as size of particles decreases vertically in the air column. It seems that the upper limit of aeolian sediment transport at Mesrug is 0.8 m above the ground and saltation of ...