Related Experiment Videos
Controls on quartz silt formation by crystalline defects.
R Kumar1, I F Jefferson, K O'hara-Dhand
1Civil Engineering, School of Engineering, University of Birmingham, Birmingham, B15 2TT, UK.
Die Naturwissenschaften
|February 28, 2006
Summary
Glacial grinding of quartz produces silt, but the amount depends on the quartz source. Experiments show sedimentary quartz yields more silt than vein quartz due to internal mineralogical controls.
Area of Science:
- Geology
- Mineralogy
- Sedimentology
Background:
- Silt, predominantly quartz, is abundant globally.
- Its origin, particularly from glacial grinding, is debated.
- Contradictory evidence exists in scientific literature.
Purpose of the Study:
- To investigate the origin of quartz silt.
- To test the role of glacial grinding in silt formation.
- To identify factors controlling silt yield.
Main Methods:
- Simulated glacial grinding using the Bromhead ring shear apparatus.
- Experimental shearing of unweathered vein quartz.
- Experimental shearing of Leighton Buzzard sand (sedimentary deposit).
Main Results:
- Vein quartz produced minimal silt.
- Leighton Buzzard sand yielded abundant silt.
- Particle size analysis revealed modes around 20 micrometers, suggesting internal mineralogical control and defects (Moss defects).
Conclusions:
- Quartz silt formation is influenced by lithological factors.
- Internal mineralogical properties of quartz control silt yield during weathering.
- This explains common silt modes observed in deposits like loess.