Transport conditions of mountain-surging glaciers as recorded in the micromorphology of quartz grains (Medvezhiy Glacier, West Pamir)
Journal Title: Geologos - Year 2015, Vol 21, Issue 2
Abstract
In order to reproduce the conditions under which sediments were transported in surging glaciers, samples were taken from the margin and foreland of the surge Medvezhiy Glacier situated in West Pamir (Tajikistan). They were subjected to an analysis of rounding and frosting of quartz sand grains (0.8-1.0 mm) and of grain surface micromorphology under scanning electron microscope (SEM). Results obtained showed intense chemical weathering occurred in the majority of quartz grain surfaces, marked in the form of etching and precipitation. Frequencies of microstructures of glacial origin were low; individual microstructures were visible on single grains. A predominance of the crushing process over abrasion in transformation of quartz grains was noted. The commonest microstructures connected with a surge-glacier environment were large and small conchoidal fractures. However, grains with primary features not connected with a glacial environment were equally common. The majority of the grains examined showed features of multiple cycles of mechanical and chemical weathering forming a microtexture under various conditions (overprinting). Common features of grains from surging glaciers are also breakage blocks of >10µm, which depend of the phase of separation of the grain from the rock or on thermal changes in the glacier's foreland.
Authors and Affiliations
Agnieszka Muzińska
Keywords
Related Articles
- EP ID EP166440
- DOI 10.1515/logos-2015-0009
- Views 160
- Downloads 0
Middle Jurassic-Early Cretaceous foraminiferal biozonation of the Amran Group, eastern Sana'a Basin, Yemen
Two sections of strata assigned to the Amran Group at Jabal Salab and Jabal Yam in the eastern Sana’a governorate were sampled and correlated. These sections are part of a carbonate platform that extends from the city of...
Did plate tectonics control the generic diversity of Jurassic brachiopods? One point of view
Possible plate tectonic controls on faunal diversity dynamics have been discussed in the geological literature for around 50 years. The new model of plate tectonic processes is here linked to Jurassic generic diversity (...
The life cycle of seismite research
seismites, review
Mantle rock exposures at oceanic core complexes along mid-ocean ridges
The mantle is the most voluminous part of the Earth. However, mantle petrologists usually have to rely on indirect geophysical methods or on material found ex situ. In this review paper, we point out the in-situ existenc...
Seismic and non-seismic soft-sediment deformation structures in the Proterozoic Bhander Limestone, central India
Numerous soft-sediment deformation structures occur within the Proterozoic Bhander Limestone of an intracratonic sag basin in a 750 m long section along the Thomas River, near Maihar, central India. Part of these deforma...